Andromeda Galaxy

M 31 • NGC 224 • UGC 454 • PGC 2557 • CGCG 535-017 • MCG + 07-02-016 • IRAS 00400 + 4059 • 2MASX J00424433 + 4116074 • GC 116 • h 50 • Bode 3 • Flamsteed 58 • Hevelius 32 • Ha 3.3 • IRC +40013

The Andromeda Galaxy, also known as the Andromeda Nebula or the Great Andromeda Nebula, is the closest spiral galaxy to the Milky Way , around 2.5 million light years away. It is located in the eponymous constellation Andromeda and is the most distant object that can be observed with the naked eye under good conditions without technical aids. It is often referred to as M 31 for short after its entry in the Messier catalog .

The Andromeda Galaxy is similar to the Milky Way. Both galaxies host the same types of astronomical objects , but from the “outer” perspective of the Milky Way there is a better view of the structure of the galaxy. There are dark bands of dust, star formation areas and more than 200, possibly 500 globular star clusters in the outer area . Its individual stars can also be observed in ever larger areas. The galaxy has a massive black hole of around 100 million solar masses in the center, spiral arms extend from it up to a distance of around 80,000 light years, its halo extends over a million light years.

In terms of halos, the Andromeda Galaxy is the largest member of the Local Group , a collection of gravitationally bound galaxies. The Andromeda Galaxy and the similarly massive Milky Way are by far the two most massive galaxies in the Local Group and each bind a large number of satellite galaxies to themselves. The estimated values given in the more recent literature for the mass of the Andromeda Galaxy range between 0.7 and 2.5 billion solar masses, of which its stars account for around 100 billion solar masses.

The Andromeda Galaxy has long been studied scientifically. However, it was not until the end of the 19th century that the object, which had previously only appeared as a nebula in telescopes, was able to be identified - to recognize that it is a spiral nebula made up of stars. Using the Andromeda Galaxy, it was then determined in the 1920s that spiral nebulae are independent star systems located outside the Milky Way. This was accompanied by the knowledge that the universe consists of numerous other galaxies in addition to the Milky Way. Deviations between the calculated and observed rotation in the Andromeda Galaxy have indicated dark matter or a deviation from Newtonian dynamics since around 1940 . Since the turn of the millennium, more and more traces of a collision with another galaxy have been found.

exploration

First descriptions and theses on nature

Oldest surviving representation of the Andromeda Galaxy (as a point group in the mouth of the fish) in Al-Sufi's book of fixed stars (copy from approx. 1010)

The first reliable description of the Andromeda Galaxy comes from the 10th century AD by the Persian astronomer Al-Sufi , who called it "the little cloud". Charles Messier attributed the discovery to Simon Marius when it was entered in his catalog . In fact, he was the first to observe them through a telescope in 1612 and found that he could not resolve the Andromeda nebula into individual stars even with the telescope. This is where the name Andromeda fog comes from.

Although the mostly round or oval shape of starless nebulae was recorded by William Derham as early as 1733 , the exact nature of these structures remained unknown for a long time. Often they have been viewed as part of the Milky Way system. On the other hand, Immanuel Kant already considered in 1755 that with the appropriate direction of observation, the elliptical shape of a distant disk-shaped star system similar to the Milky Way could result. Wilhelm Herschel wrote in 1785 that the Andromeda Nebula is believed to be the shimmer of millions of stars, shaped similarly to the Milky Way, and that a connection between them is unlikely. Due to its structure and the slightly reddish color of the center, he located it closer than other such nebulae. His distance seemed to be at most 2000 times the distance from the star Sirius . Shortly afterwards, however, he was unable to confirm the delimitation of the Milky Way with more powerful telescopes, and later he had doubts about the nature of the nebula after he believed he could see stars behind it; his earlier hypotheses, however, formed an important new approach that was often taken up.

Drawing of the Andromeda nebula and the nearby nebulae M 32 (below) and M 110 (above right), Charles Messier , 1807

Photograph of the Andromeda Nebula, Edward Emerson Barnard , 1887

The first drawings of the Andromeda Nebula were published by Guillaume Le Gentil in 1759 and Charles Messier in 1807. George Phillips Bond found more detailed information about the shape in 1847 with the Great Harvard reflector and Lawrence Parsons in 1871 with his 6-foot telescope which he published in 1885. However, it was only photographs of the Andromeda Nebula from 1887 and 1888 by Edward Emerson Barnard and Isaac Roberts that showed the shape comprehensively, and thus provided further, differently interpreted indications of the nature of this nebula. Roberts himself saw in it a developing solar system , around whose central sun rings have formed and planets are already forming from the nebulae M 110 ( h 44 ) and M 32 ( h 51 ) located there . In 1914, John Reynolds suspected, due to the similarity of the brightness curve of M 31, which can be determined from photographs, with that of reflection nebulae around stars, that M 31 is also such. On the other hand, Arthur Stanley Eddington favored the hypothesis a year later that the spiral nebulae were separate "island universes", and justified this interpretation with the fact that significantly fewer spiral nebulae were found in the Milky Way than in higher galactic latitudes. This could be explained by the dark bands observed in the plane of the Milky Way, which absorb the light of the distant nebulae behind. Such dark bands could also be seen in photographs of spiral nebulae. The spiral shape of M 31 was previously believed to be possible shortly after the discovery of spiral nebulae by Parsons' father around 1850 and, based on other photographs, was also considered proven.

A star-like flashing and fading in 1885 near the center of the Andromeda Nebula was considered an important argument for the proximity of the Andromeda Nebula. For a long time there was no process conceivable that could release so much energy to explain such a brightness at a greater distance. One of the discoverers of this event, Ernst Hartwig , wondered, for example, whether the observation resulted from just ignited gas masses in the Andromeda nebula, which had previously glowed weakly at a low temperature and now exceeded in brightness the core of the nebula that had previously formed in the same way.

With the help of spectroscopy , William Huggins recognized as early as 1864 that the Andromeda Nebula and M 32 were similar and distinguished them from the planetary nebulae characterized by spectral lines ; but the spectra could not be conclusively classified. Julius Scheiner succeeded in doing this in 1899 through photographs of the faint spectra that have now become possible. With a 7.5 hour exposure, he found that

"The previous assumption that the spiral nebulae are star clusters has been raised for safety,"

and thus found it plausible, and based on other features, if the Milky Way were a spiral nebula like Andromeda.

In 1912, Vesto Slipher calculated the heliocentric radial velocity from M 31 to 300 km / s in the direction of the sun based on the blue shift of the spectral lines , which was the highest up to now recorded for an object (modern measurements result in 300 ± 4 km / s). Shortly afterwards he discovered velocity curves in the spectrograms of another spiral nebula, which indicate a rotation of the spiral, and also found evidence of this rotation in the spectrograms of the Andromeda nebula. A series of partly even larger and differently directed radial velocities of spiral nebulae, which he had subsequently determined and which differ fundamentally from those of the stars, he considered to be evidence of their "island universe" nature. The rotation of the Andromeda Nebula was confirmed and quantified by Francis G. Pease in 1918.

distance

Julius Scheiner made an estimate of the distance in 1900. Motivated by the findings from his spectral analysis and because of the many matching features between the Andromeda Nebula and the Milky Way, he considered that both systems could also match in size “roughly”. Under this condition, the apparent expansion in the firmament of 3 ° resulted in a distance of 20 times the diameter of the Milky Way - according to current knowledge, a value that is accurate to within a few percent. At that time, Scheiner calculated 0.5 million light years due to a smaller known extent of the Milky Way. During this time, other researchers suspected a connection between the Andromeda Nebula and the stars observed there and thus a close location within the Milky Way.

At four observed in spiral nebulae Novae realized Heber Curtis in 1917 that these average 10 magnitudes were fainter than other novae, which can be explained by a 100-fold greater distance from the Milky Way. Including novae in the Andromeda Nebula, Harlow Shapley deduced a distance of around 1 million light years from this in the same year, but saw this in contradiction to the appearance from 1885 and a supposedly recognizable angle of rotation of spiral nebulae between photographs taken at different times. The arguments in favor of a location of the Andromeda Nebula on the edge of the Milky Way or far outside and thus helping to clarify the structure of the universe were brought together by Shapley and Curtis in the so-called " Great Debate " in 1920.

Image of a 40,000 light-year area of the Andromeda Galaxy with the Hubble Space Telescope . In the original image with a resolution of 1.5 billion pixels, thousands of star clusters and over 100 million individual stars can be seen, 178 of which are Cepheids , which were used for precise distance determination.

Other methods of determining distance were developed in the period that followed. From the local distribution density of further novae that have since been observed around the Andromeda Galaxy, a distance of the equivalent of 3 million light years was determined in the early 1920s. Ernst Öpik designed a model of the Andromeda Galaxy based on the orbital speeds of its stars, measured spectroscopically by Francis Pease, and derived a distance of around 1.5 million light years from this. In 1923, Edwin Hubble succeeded in using the recently built telescope, which is 2.5 meters in diameter and is the world's largest telescope , to discover variable stars of the Cepheid class in the Andromeda Nebula, to calculate their distance to 900,000 light years and to convince Shapley that the Andromeda Nebula - and so that all spiral nebulae are separate galaxies. He used the period-luminosity relationship determined in the globular clusters of the Milky Way on Cepheids , with which he concluded the luminosity and, from this, the distance of the Cepheids in the Andromeda Galaxy. At the beginning of the 1930s, Walter Baade and Fritz Zwicky discovered a plausible process for the lighting up in 1885, which they referred to as a “ super nova ”. At the beginning of the 1950s, Walter Baade found out with the help of the recently completed 5-meter-diameter Hale telescope that the Cepheids used by Hubble belonged to a previously undiscovered class that was twice as bright, and corrected the distance to over 2 million light-years. When large telescopes were equipped with much more sensitive CCD image sensors , an evaluation of the " Tip of the Red Giant Branch " in 1986 showed a distance of 2.47 million light years, and in 1987 the discovery and evaluation of RR-Lyrae was also successful Stars in the Andromeda Nebula ; it was able to determine the distance to 2.41 million light years with an accuracy of 7%. In 1998, a precise determination of the distance using so-called red clump stars of 2.56 million light years was achieved with a systematic and statistical uncertainty of 1.6% and 2.2%. The measurement of an eclipsing star in M 31 by the Institut d'Estudis Espacials de Catalunya / CSIC in 2005 also showed a distance of 2.52 ± 0.14 million light years. Subsequent more detailed investigations on the Cepheids with the Hubble space telescope and the "Tip of the Red Giant Branch" showed similar distances with even better precision.

Satellite galaxies

Local group: The position of the satellite galaxies around the Andromeda Galaxy can be seen

At the end of the 18th century, while observing the Andromeda Nebula, Charles Messier noticed two other nebulae in his telescope's field of view, which appeared to accompany the Andromeda Nebula. After Edwin Hubble succeeded in determining the distance using Cepheids at the beginning of the 20th century, he found that these three objects are about the same distance and are therefore also close to each other in the third dimension of space, i.e. in the viewing direction: They are therefore members of the Local group of galaxies found by him , in which the Andromeda Galaxy with these two companion galaxies Messier 32 and NGC 205 form a subordinate system. Sidney van den Bergh recognized in 1968 that other previously known galaxies can be assigned to the Andromeda system, namely NGC 147 , NGC 185 and the Triangle Nebula (M 33) . Shortly afterwards, van den Bergh found four more previously unknown galaxies with the help of a special telescope with a wide field of view and particularly sensitive photo plates and named them Andromeda I – IV. With this combination of telescope and photo plates, a large-scale sky survey was carried out in the 1980s and 1990s , in which the satellite galaxies Andromeda V , VI and VII were found in 1998 .

Other companion galaxies were discovered with larger telescopes, equipped with optics for a wide field of view , with CCD image sensors that are more sensitive than photo plates, and using computer-automated image evaluations, for example the galaxies Andromeda XI – XIII with the help of the CFHT's Megacam . This investigation also made it possible to estimate that there must be 25–65 satellite galaxies around the Andromeda Galaxy. With this telescope, the galaxies Andromeda XXI – XXVII were discovered in the following years, others with SDSS and Pan-STARRS . Since 2013, 40 smaller galaxies have been known to surround M31. In almost all of these galaxies, the gravitational bond to the considerably heavier Andromeda Galaxy has been proven. In a selection of 27 galaxies, the tip of red giant branches was used to determine that 13 were at a distance of 67–134 kpc, 10 at 134–268 kpc and 4 at 268–482 kpc. Most of the M 31 satellite galaxies are spherical or irregular in shape. Many are in the same plane and are therefore possibly the remains of a long-ago merger of M 31 with another galaxy.

Proper movement

The motion of the Andromeda Galaxy in relation to the Milky Way was studied by Jaan Einasto and Donald Lynden-Bell in 1982; they determined a radial speed in the direction of the center of the Milky Way of 123 km / s and a transverse speed of 60 km / s. This radial velocity value agreed with the results of John N. Bahcall and Scott Tremaine from last year, and recent studies show that the Andromeda Galaxy is approaching the center of the Milky Way at a radial velocity of about 114 km / s (approx. 410,000 km / h) approaching. This value is different from the heliocentric radial velocity, i.e. H. the speed with which M 31 is moving towards the sun. Since the sun for its part orbits around the galactic center of the Milky Way and is currently moving towards M 31, the heliocentric radial velocity of M 31 has a significantly higher amount of around 300 km / s (approx. 1 million km / h).

The transverse speed of M 31 could be measured for the first time in 2012 using precise star field studies within the galaxy with the Hubble space telescope . The measurements result in a tangential speed of 17 km / s and thus confirm interim estimates that this does not significantly exceed 20 km / s. There was also a slightly lower radial speed of 109 km / s. Investigations of the satellite galaxies of M 31 from 2016, however, indicate a higher transverse speed of 150 km / s; Measurements with the astrometry satellite Gaia are slightly lower. After the discovery of H ₂ O measles in 2011, a more precise measurement of proper motion seems to be possible in the near future, as was already possible in the case of the Triangle Nebula.

Computer simulations suggest that the Andromeda Galaxy will collide with the Milky Way in four to ten billion years and that both will merge into an elliptical galaxy or, through a special form of interaction between galaxies , into a polar ring galaxy .

Mass and rotation

Rotation curve 31 M Optical (orange)
and based on the HI-line (blue)
rotational speeds determined

Ernst Öpik carried out the first determination of the mass of the Andromeda Galaxy together with the determination of the distance in 1922. He reasoned that the stars are directed to circular orbits around the center by the gravitation caused by the mass. For this orbit, the mass results directly from the orbital speed and diameter : With an orbital or rotational speed previously measured spectroscopically by Francis G. Pease, 1.8 billion solar masses (M _☉ ) had to be located near the center , extrapolated to the entire galaxy 4.5 billion M _☉ . Edwin Hubble also calculated a similar value, taking into account his distance determination. Around 10 years later, Horace Babcock as well as Arthur Bambridge Wyse and Nicholas Mayall extended this method to a much larger area with a 3.2 ° diameter, and thus determined a significantly higher mass of around 1 while avoiding extrapolation.0e¹¹ M_☉. With the distance of around 2.3 million light years corrected by Baade,Maarten Schmidtthencalculateda mass of3in 1957.4the¹¹ M_☉, 94% of it within a radius of 44 kpc.

While Öpik assumed a constant mass density-luminosity ratio for his extrapolation and Schmidt considered this to be compatible with his observations, Babcock, Wyse and Mayall arrived at a different result. They deduced from the rotation curve , which has an almost horizontal course for larger distances, that a large part of the mass must be present in this area. A comparison with the decreasing brightness curve in the outdoor area showed a clearly increasing mass density / luminosity density ratio there. They wondered whether absorption, a new dynamic or a kind of less luminous matter was the cause. Vera C. Rubin and Kent Ford confirmed the phenomenon in 1970 and subsequently found it in a number of spiral galaxies; Rubin saw this as evidence of dark matter in the outer reaches of the spiral galaxies.

After radio emissions from M 31 were discovered for the first time in the early 1950s, the mass determination was soon carried out using rotation curves on the HI line of circling neutral hydrogen clouds. These examinations showed a slightly higher mass in the range up to 30 kpc of 2.5e¹¹ M_☉. Later investigations showed that the spiral structure can also be determined in the HI emission, and taking this into account, no additional, non-luminous mass up to a radius of 28 kpc is required. For a larger radius of 159 kpc around the center of the Andromeda Galaxy, an extrapolated mass 10 resultse¹¹ M_☉ or, more broadly, 13e¹¹ M_☉ . The authors of one of these studies see the state of knowledge both in accordance with postulated dark matter, alternatively also in accordance with a modified Newtonian dynamics .

As early as 1936, Edwin Hubble considered that a mass determination for the members of the local group could be derived from the individual, easily determined radial velocities. Two different such methods were compared in studies around 1980. The methods delivered different orders of magnitude, 1… 2e¹¹ M_☉using thevirial theoremand 13e¹¹ M_☉ , which agrees significantly better with extrapolated measurements on HI areas. The movement of Andromeda satellite galaxies found in the meantime as well as globular star clusters and planetary nebulae lying in the outer area of the AndromedaGalaxy were used in 2000 to determine the mass of the galaxy's halo, resulting in a total mass of 12e¹¹ M_☉ with a scale length of now 90 kpc. A mass of 7 is also used to explain the stellar currents around the Andromeda Galaxy that were discovered during this period.5e¹¹ M_☉, according to recent studies from 21e¹¹ M_☉ , required. A more recent survey of globular clusters in the outer halo yields 12… 16e¹¹ M_☉similar results. The studies of the three-dimensional motion of the Andromeda Galaxy and the Triangle Nebula using the Hubble Space Telescope, completed in 2017, revealed a mass of 14e¹¹ M_☉ with an uncertainty of about a factor of 2. In a study written in 2018, an overview is given of a large number of previous studies and it is shown that all of their estimated values for the mass of the Andromeda Galaxy are between 0.7 and 2.5 trillion Moving solar masses.

Halo

Long exposure photo of M 31, partially inverted on the right, to clarify the structure of the halo: nomenclature of the stellar streams and contour of the "Giant Stellar Stream" (GS)

Gerard de Vaucouleurs mapped the brightness of the Andromeda Galaxy at the end of the 1950s and found a superimposed spherical component that spanned the galaxy. This component followed the profile of elliptical galaxies previously found by de Vaucouleurs , in which the magnitude of the surface brightness decreases reciprocally to the fourth power of the distance from the center. It dominates the brightness of the galaxy near the center and, if one extrapolates its course, at a distance of over 3 °, an area in which Walter Baade had already found stars of the Andromeda Galaxy. Further research confirms this component up to a distance of about 20 kpc and refers to it as a halo.

In 2005, a structure extending beyond this was discovered with the help of the 10 meter diameter Keck telescope . While the previously known component consists of stars of high metallicity , the more extensive structure is made up of stars of lower metallicity. Their brightness curve decreases proportionally with the distance . Even at a distance of 175 kpc (over 500,000 light years) from the center, stars of the galaxy could still be detected by spectroscopic assignment of individual red giants . In 2001, a large stellar stream was also discovered in the halo of the Andromeda Galaxy, which is referred to in the literature as the "Giant Stellar Stream". Another was later also found in the northwestern area of the galaxy, stretching over 100 kpc. ${\ displaystyle r}$ ${\ displaystyle r ^ {- 2,3}}$

The ionized elements silicon and carbon are detectable up to a distance of almost 300 kpc from the center, the viral radius , and leave a total mass of 1 in this areae_Assume¹⁰ M_☉ of gas. This discovery was made by using the Hubble Space Telescope and the Far Ultraviolet Spectroscopic Explorer to determine the characteristic absorption of these elements in the ultraviolet spectrum of the light of the quasars behind them. Further indications can be obtained from smaller satellite galaxies, which only show a signature of embedded hydrogen from a distance of 270 kpc. In the case of satellite galaxies at shorter distances, the hydrogen could have been withdrawn through interaction with the gas contained in the halo of M 31.

Whether dark matter manifests itself in the halo of the Andromeda Galaxy or the Milky Way through MACHO has been investigated using the microlens effect since the 1990s. Many observatories have tried to observe this effect, including the Mayall Telescope , the Isaac Newton Telescope , the Télescope Bernard Lyot , the Himalayan Chandra Telescope , the Vatican Advanced Technology Telescope , the Pan-STARRS, and the Cassini Telescope in Loiano . The results up to 2015 suggest that less than 30% of the mass of the halo is likely made up of MACHOs. In particular, the assumption of primordial black holes as an essential component could be investigated and refuted using the Hyper-SuprimeCam of the Subaru telescope .

Dust and gas structure

Infrared emission of M 31 Links: The wavelength range of 24-160 microns was added by means of the Spitzer Space Telescope ; the 1–1.5 kpc ring structure near the center appears blue-green in this figure due to its higher temperature. Right: The wavelength range 250–500 µm recorded with the Herschel space telescope ; the “10-kpc-ring” is whitish in this illustration, the easily recognizable dust lying further outside is brownish due to the lower temperature.

Arthur Stanley Eddington pointed out the dark ribbons that run through spiral nebulae in 1914 and interpreted them as absorbing matter in the nebulae. Edwin Hubble soon realized that it could only be dust , perhaps paired with gas. The first direct observations of the cold dust , which only shines in the infrared, and quantitative evaluations based on it, were made in the early 1980s by overcoming the disruptive atmosphere with the help of the infrared astronomical satellite . With this, M 31 was investigated in 1984 in the wavelength range from 12–100 µm, from which a dust mass of 3,000 M _{☉ was} calculated. Subsequent observations by the Infrared Space Observatory in 1998 revealed a dust mass of 3e⁷ M_☉ , predominantly with a temperature of 16 Kelvin in a ring with a radius of 10–12 kpc and a weaker one in 14 kpc around the center; near the center the dust has a temperature of 28 Kelvin. The analyzes with the help of the Infrared Space Observatory werelargely confirmedon the basis of more precise images in 2006 using the Spitzer Space Telescope and in 2012, expanded to 500 µm wavelength with the Herschel Space Telescope . It turned out that the galaxy 5.8the⁷ M_☉mass of dust, 78% of which is contained in the two rings. The image from the Spitzer Space Telescope shows a ring near the center with a diameter of 1-1.5 kpc, which is about 0.5 kpc off-center. There was also another dust ring with a radius of 5.6 kpc, the expansion of the "10 kpc ring" was numbered up to a radius of 11.2 kpc, and an overlaid spiral structure was found. 75% of the dust is composed ofsilicatesandsilicon dioxideand 25% of carbon-containing compounds. Polycyclic aromatic hydrocarbons makeup 4% of them. The higher temperature of the dust in the center is caused by the more intense radiation from the stars that appear more densely there.

Initial studies of the mass of non-ionized hydrogen (HI) from the 1950s showed 4e⁹ M_☉ , and its distribution shows a pronounced ring in a radius of 10–12 kpc around the center of M 31. According to more recent studies, it is 5.4the⁹ M_☉about 100 times the mass of dust. During these investigations, the spiral structure was also found in the HI emission and a deformed disk structure of the galaxy was revealed. Excited hydrogen was mapped using theHα linein 1994. It showed a strong correspondence with the radiation in the far infrared, in particular areas of the 10-kpc-ring emerge prominently and there point toH-II areasof star formation.

With the help of indirect evidence of an emission of the traces of carbon monoxide (CO) , it was possible to determine that less than 10% of the hydrogen formed H ₂ molecules, 3.6the⁸ M_☉within a radius of 18 kpc. It was also shown that the molecular gases follow the ring or spiral dust structures much more clearly than the atomic hydrogen. With this method, a rotating gas disk in the central area with a diameter of 1–1.5 kpc could also be observed, which is tilted in relation to the rest of the galactic disk.

Magnetic fields

M 31 recorded with the aid of the Effelsberg radio telescope at 6.2 cm wavelength: central area and “10 kpc ring” emerge. The magnetic field determined from the linear polarization is shown superimposed, with the orientations being systematically rotated by about 20 ° due to the Faraday rotation of the Milky Way.

Linearly polarized light from areas of M 31 was discovered in 1942. Investigations with the 300-foot radio telescope and the one-mile telescope revealed evidence of galaxy-wide magnetic fields in the 1960s . By observing linear polarization also in the radio range, these magnetic fields could be detected with the Westerbork Synthesis Radio Telescope , the 100-m Radio Telescope Effelsberg and the Very Large Array : The only plausible cause of the polarization was synchrotron radiation , which was caused by electrons at almost the speed of light Magnetic field is generated. The total magnetic field has an average strength of about 5e^-10 Tesla, of which about3e^-10 Tesla are classified. The formation can be described by adynamo effectin the galactic disk.

Further investigations followed in the frequency range from 350 MHz to 8.4 GHz. The direction of the magnetic field roughly follows the direction of the “10 kpc ring”. However, another magnetic field occurs up to a distance of 0.5 kpc from the center, with a differently directed radial component and orientation, and confirms the separate, differently oriented rotating gas disk there.

Stars

Edwin Hubble recognized in the 1920s that the appearance of almost all galaxies can be classified by a few types , and he typed the Andromeda Galaxy as a barless spiral galaxy with a prominent central area, called "Sb". In 1942, Walter Baade was able to use the largest telescope available at the time, the Hooker telescope with a 100-inch aperture, to identify individual stars for the first time in photographs of the central area of the Andromedan Galaxy. It turned out that the stars of spiral galaxies are formed from two different populations , in contrast to the elliptical satellite galaxies. Julius Scheiner had already determined that the spectra of the stars in the center and in the edge area differ.

The mass of the stars up to a distance of 30 kpc from the center is 10.3e¹⁰ M_☉, researchers suspect a total of one trillion stars. They are divided into different components:

spherical bulge , 23%,
Disc, 73%, and
Halo , 4%,

a box- / peanut-shaped bulge or a bar structure can also be assumed. The stars in the spherical bulge move randomly, their logarithmic surface brightness falls in the range 0.2–20 kpc reciprocal to the 4th power of the distance to the center, so that from around 1.2… 2 kpc the brightness of the disk predominates.

The disk has the spiral structure that characterizes the type of galaxy. This structure was clarified and examined in more detail by John H. Reynolds in 1926 on the basis of a stretching of a picture of M 31 as it corresponds to a plan view, tabulated by Walter Baade in the 1960s and further analyzed by Halton Arp . Baade noted the spiral arms he recognized on the basis of their passage on the southern and northern sections of the main axis; Arp documented the course of the spiral arms formed by stars using emission nebulae associated with the stars and approximated the course of the arms using logarithmic spirals . The spiral structure was subsequently discovered in the infrared, interpreted and modeled as a mixed ring-spiral form: The spiral segments observed cannot be explained in the classical way by density waves ; rather, an external disturbance must be taken into account, for example an interaction with a satellite galaxy.

Spiral arms from M 31 to Baade, distances from the center
(assuming a distance to the Milky Way of 735 kpc)
poor	distance		poor	distance
N1	3.4 ′	0.7 kpc	S1	1.7 ′	0.4 kpc
N2	8.0 ′	1.7 kpc	S2	10.5 ′	2.1 kpc
N3	25.0 ′	5.3 kpc	S3	30.0 ′	6.3 kpc
N4	50.0 ′	11.0 kpc	S4	47.0 ′	9.9 kpc
N5	70.0 ′	15.0 kpc	S5	66.0 ′	14.0 kpc
N6	91.0 ′	19.0 kpc	S6	95.0 ′	20.0 kpc
N7	110.0 ′	23.0 kpc	S7	116.0 ′	24.0 kpc

GALEX absorbs the ultraviolet radiation from M 31 . Rings with hot young massive stars appear blue and white. Dark blue and gray stripes indicate cold dust in which stars are just forming. The orange-white center indicates mostly colder old stars.

The ages of the stars have been studied variously. UV images using GALEX show that only minimal star formation has occurred between the bulge and the 5 kpc ring in the last 500 million years. A spectroscopic examination using the Harlan-J.-Smith telescope showed that 80% of the stars in the bulge are between 11 and 13 billion years old and have a high level of metallicity , with a different metallicity in the bar. In the disk there are many stars with an age of 3–4 billion years, with the outer area of the disk being dominated by stars with an age between 4 and 8 billion years and stars up to 13 billion years old can also be found. Recent studies show an increased star formation 2 billion years ago. As determined by the Hubble Space Telescope, star formation currently occurs primarily in the 10 kpc ring that formed 400 million years ago. Star formation in the outer 15 kpc ring began 80 million years ago, while star formation in the inner 5 kpc ring peaked 200 million years ago and is now much lower than in the other rings.

Star formation in M 31 can also be seen in young star associations and open star clusters . One prominent star association is NGC 206 , which was discovered by William Herschel in the 18th century and roughly classified by Hubble in 1929. In 1964, Sydney van den Bergh found 188 young star associations formed from stars of the spectral classes O and B with the help of the Schmidt telescope in Tautenburg and concluded that another one emerges in the spiral arm segments about every 100,000 years. A systematic study by Paul W. Hodge in 1979 with the Mayall Telescope revealed over 400 open star clusters . They are 1 ... 100 million years old and are located on the spiral arm segments, particularly pronounced at 50 ′ and 68 ′, which form the 10 kpc and 15 kpc rings.

Globular clusters

As early as the early 1930s, Edwin Hubble recognized that 140 protruding objects in the Andromeda Galaxy are probably globular clusters, although they differed more in their luminosity and were too faint for the distance he assumed about 0.8–2.0 may be. An exemplary spectroscopy carried out shortly afterwards by Milton Lasell Humason supported this classification. Walter Baade discovered around 100 other globular clusters that were published in 1945. A reduced brightness of 2.5 mag this time was again found, which Baade was able to resolve around 10 years later by correcting the distance. A large number of other candidates were identified in the 1980s with the help of automated surveys according to their typical appearance or spectrum. The greater scattering of the luminosity compared to the globular clusters of the Milky Way was confirmed. Since the beginning of the 21st century, more than 250 globular clusters have been detected using the Hubble space telescope, which means that around 460 globular clusters are assumed to be in the Andromeda Galaxy. Of these, Mayall II is not only the largest in its galaxy, but of the entire Local Group. In 2005, three star clusters of an entirely new type were discovered in the Andromeda Galaxy. With a comparable number of stars, it differs from previously known globular clusters in that it is larger and therefore less dense.

In the age structure of the globular clusters, the Andromeda Galaxy differs fundamentally from the Milky Way. While the galactic globular clusters have a low age dispersion, there are globular clusters in at least three age groups in the Andromeda Galaxy: on the one hand, those that are as old as the galaxy itself, on the other hand, significantly younger ones with an age of a few hundred million years, and finally a small third Group with globular clusters, the age of which is about 5 billion years. The young globular clusters are in the star formation regions of the galactic disk, especially in the 10 kpc ring, while the old ones are in the halo. The most distant globular cluster, MGC1, is 200 kpc from the center, which is also the highest distance in the local group, as was determined in 2010 using one of the Gemini telescopes .

The movement of globular clusters in the halo was analyzed in more detail in 2019. The previously observed rotation of the globular clusters in the alignment of the disk results from two superimposed subgroups in the globular clusters that rotate approximately perpendicular to each other. One subgroup is aligned with the plane of the satellite galaxies, the other carries structures of the star currents. Both can be explained as relics of an absorption from a different galaxy.

Central region

Image of the center of M 31 using the Hubble space telescope and a model (bottom right, shown enlarged opposite the image) of the core, a disk of blue stars closely revolving around the black hole and elliptically revolving red stars

X-ray sources near the center of M 31, taken with the Chandra Space Telescope ; enlarged below right: Alternating images of the center from 2006 and from the time before, in which the supermassive black hole 2006 lights up

The prominent core of the Andromeda Galaxy was investigated in more detail from the late 1950s. It has an apparent diameter of about 5 arc seconds and is partly similar to a globular cluster , but with a hundred times higher mass, twenty times higher luminosity, an elliptical shape and a different color gradient. The orbital speed of the stars around the center shows a high value of 87 km / s at a radius of 2.2 arc seconds, followed by a minimum close to zero at about twice the radius. The first high-resolution examinations of the core, carried out with the balloon-borne Stratoscope II , showed no evidence of a black hole in the measured brightness curve in the early 1970s . Spectroscopic analyzes of the central stellar velocities from this time revealed a core mass of 6e⁹ M_☉ or according to the virial theorem 1.8the⁸ M_☉and calculations showed that a supermassive black hole is conceivable.

Evidence of a black hole was found in investigations in the late 1980s. First recordings with the high-resolution camera of the Hubble space telescope showed that the center has two brightness maxima. For a long time it was therefore thought that the Andromeda Galaxy had a double core, consisting of two supermassive black holes and a few million densely packed stars. It was assumed that one of the two black holes came from an earlier collision with another galaxy. More recent data from the Hubble Space Telescope from 2005 only allow the conclusion that the core consists of a ring of older red and a ring of younger blue stars that are trapped in the gravitational field of a supermassive black hole. The orbital speeds of the stars reach 1700 km / s at a distance of 0.05 arc seconds or 0.19 parsecs, which can only be achieved through a black hole with a mass of about 1.4the⁸ M_☉can be explained. The subsequent discovery of a hydrogen disk orbiting the center and investigations of its speed of rotation based on theHα lineresulted in a slightly lower value of 5e⁷ M_☉ . With an assumed 100 million solar masses, the black hole in the center of Andromeda is around 24 times as massive as the black hole Sagittarius A * in the galactic center of the Milky Way.

Further properties of the central region were determined by observation in other spectral ranges. In the X-ray range that can only be observed outside the atmosphere , the Andromeda Galaxy has been studied since the early 1970s, starting with the Uhuru satellite . In the center of the galaxy, a number of radiation sources can be made out that have been separately mapped using the Chandra space telescope since 2000 . These are presumably diffuse hot gas, globular star clusters, supernova remnants , planetary nebulae and stars, as well as neutron stars and black holes that remove material from accompanying stars. The supermassive black hole can also be seen on it, although it has a comparatively low luminosity; a lighting up in 2006 and a subsequent decrease to an increased radiation level could not yet be conclusively explained physically in a study from 2011. Immediately around the black hole, the gas in the gas cloud in the center is missing, as shown by radio interferometry . Combined studies with the XMM-Newton and Chandra X-ray telescopes suggest that the black hole may have formed an active galaxy core 500,000 years ago .

Interactions with satellite galaxies

The deformation of the galactic disk, which was discovered by radio astronomy in the 1970s, opened up initial speculations as to whether an interaction with a satellite galaxy like M 33 could be a cause for this. Since the 2000s, many other indications of an interaction in the halo, in the structure of the disk, in the history of star formation and in the orbits of satellite galaxies and globular clusters have been found, which have led to a number of partly contradicting theses about the process and the galaxies involved :

The observed ring structure of gas and dust allows conclusions to be drawn about their formation: The decentered 1 to 1.5 kpc ring and the 10 kpc ring could be from a passage of M 32 through the disk of M 31 210 million years ago have been caused. An interaction with M 32 is also suspected to be the cause of the tilted gas disk near the center.

The investigations of the globular clusters indicate several interactions. The age structure of the globular clusters, like the age structure of the other stars, makes an interaction 5 billion years ago plausible; The globular clusters that are several hundred million years old could also be explained by the absorption of a companion galaxy. Furthermore, an analysis of the orbits suggests at least two events, one dating back several billion years and one in the recent past. Based on an observed fixed mass fraction of globular clusters in a galaxy, conclusions can be drawn about the masses of the previous galaxies based on the globular clusters remaining from the respective mergers, 1.9e¹¹ M_☉and1.5e¹¹ M_☉.

The course of brightness of the bulge or halo according to a De Vaucouleurs or Sérsic profile also indicates an interaction. The stellar current and other observed properties of the halo provide detailed information and point to a collision with M 32 2 billion years ago or a close flyby of M 33 around the same time. It was also considered that a previously found connection of hydrogen between M 33 and M 31 could result from this event. However, later investigations of the proper motion of M 33 with the aid of the astrometric satellite Gaia speak against a previous approach to M 31. Simulation calculations also suggest that the cause is only partially consistent with M 32. Alternative scenarios assume complete absorption by another galaxy with 20% the mass of the Andromeda Galaxy 1.8 to 3 billion years ago, after first approaching 7 to 10 billion years ago.

Assuming a modified Newtonian dynamics , a close flyby of the Milky Way past the Andromeda Galaxy 7 to 11 billion years ago is plausible. Most of the dwarf galaxies could have been formed during this event, as can be seen in their arrangement.

Observability

On clear, dark nights, the Andromeda Galaxy can be seen with the naked eye from locations with little or no light pollution as a blurred, faint spot of light (“fog”). Essentially only the brighter central area of M 31 can be seen, the center resembles a 5th magnitude star . M 31 is best observed in autumn, the culmination for 10 ° East is on October 22nd, 11 p.m. With 10 × 50 binoculars , the central region can be seen surrounded by an elongated area, with an apparent size of 3.5 ° × 1 ° - several times larger than the full moon (around 30 ′). In a dark country sky, even the most striking dust bands can be seen. The structures become more prominent with telescopes with a larger aperture . The globular clusters in the galaxy can be observed in telescopes with an aperture of at least 30 cm.

Recordings with the help of sensitive image sensors are also possible with amateur telescopes or with digital cameras and telephoto lenses with exposure times of several hours. Emission nebulae can be highlighted by using narrow-band filters for the H-α line . It is also possible to observe individual stars in the Andromeda Galaxy and thus to understand how the distance was determined by the Cepheids.

Location of the Andromeda Galaxy in the constellation Andromeda
The image gives an impression of how the Andromeda Nebula can appear to the naked eye
Amateur shot with photomontage to compare the apparent size with the moon

reception

Popular science

The Gazebo , 1885

From the end of the 18th century, in addition to the translation of Herschel's writings, popular science books on astronomy discussed the Andromeda Nebula and described its appearance; Newspapers also refer to him, sometimes with sketches. In Meyer's large conversation lexicon for the educated classes , published in 1841, he is described as the “well-known nebula” in the constellation Andromeda.

The illustrated magazine Die Gartenlaube ran the headline in 1885 about the star-like flashing of the Andromeda Nebula observed at that time: “A world event”. Daily newspapers such as the Allgemeine Zeitung also began to report extensively in some cases on such research results, including on spectroscopy and attempted parallax measurements ; Otto Eduard Vincenz Ule had previously given such an overview in the successful and pioneering Die Natur, "Journal for the dissemination of scientific knowledge and views of nature for readers of all levels", which he published. The 1906 edition of Meyer's Großes Konversations-Lexikon also gave a comprehensive overview , together with a half-page photograph. Some articles were written by scientists, such as by Julius Scheiner in the monthly Heaven and Earth published by the Urania Society or the controversial article on the Andromeda Nebula in the supplement to the Allgemeine Zeitung from 1908 or in the illustrated magazine Natur from 1908 1914.

A popular science book published by Kosmos-Verlag in the same year 1914 went one step further and sums up that the Andromeda Nebula “with a probability that borders on certainty” is a “distant star system and that of all our Milky Way after Bau , Stage of development and shape most similar ". In 1922, the magazine Aus Natur und Museum added the distance of “over a million light years”, similarly to our world in 1930, 1937 and, with an explanation of the supernova in 1885, in 1938. The Brockhaus Handbuch des Wissens in 4 Volumes described the Andromeda Nebula in 1923 as a spectroscopically determined stellar nebula or spiral nebula, "far outside our narrow star system" at a distance of over 300,000 light years; 5 years later, Meyer's Lexicon specifies a distance of 1 million light years with reference to studies by Heber D. Curtis and Edwin Hubble of the Novae and Cepheids, and that "one sees in these [spiral] nebulae independent Milky Way systems located outside the Milky Way".

In an article in the Kosmos series from 1938 on the topic of the Andromeda Nebula, a total mass of 100 billion solar masses as well as components that correspond to the Milky Way such as open star clusters, globular clusters, albeit apparently somewhat darker , star formation areas and in particular Cepheids are shown and shown in a photo of the Andromeda Galaxy ; in another in 1951 the mass determination from the rotation curve and the star populations distinguished by Walter Baade are presented. The weekly newspaper Die Zeit reported in 1953 on Baade's discovery of different Cepheids and the resulting correction of the distance of the Andromeda Galaxy.

The universe dedicated to popular science magazines, such as the 1868 published Sirius , the 1900 published The universe, which in 1921 published the stars or from 1962 published Stars and space , reported occasionally on specific topics, most current research results, and paired them with selected Andromeda Galaxy data. Since the advent of web publications in the 1990s, popular science information about the Andromeda Galaxy has also been provided in this way, partly by research institutions themselves. Selected results are also briefly presented in the leading media Der Spiegel , Frankfurter Allgemeine Zeitung , Süddeutsche Zeitung , Die Zeit or Neue Zürcher Zeitung as well as in Der Standard .

In addition, lectures outside of academic astronomy will take place in various forms for the interested audience, sometimes on television, via YouTube or as a podcast . Also in two versions of a volume in the children's and youth non-fiction series Was ist Was , their nature as a galaxy like the Milky Way made up of billions of stars is conveyed, supplemented by illustrations and the distance determination by Edwin Hubble together with the current value of "around 3" and "2 , 5 million light years ”.

Motif

Indonesian stamp 1000 rupiah "Galaksi Andromeda", 2003

The Andromeda Galaxy is offered as an image on a number of everyday objects, such as pendants, mugs, T-shirts or puzzles; Instructions for painting the Andromeda Galaxy with oil pastel , acrylic paint or as a watercolor are available on YouTube. Stamps with the Andromeda Galaxy as a motif have been issued by various countries, for example the German Democratic Republic in 1967, Barbados 1988, Mali 1996, Germany as a special stamp 1999 with a magnetic field indented , Indonesia 2003, Bolivia 2014 and Bangladesh , Bulgaria and Estonia , France , Northern Cyprus and Turkey for the 2009 International Year of Astronomy .

Science fiction

The popularity of the Andromeda Galaxy and its properties is reflected in its use in various genres of science fiction . Since the beginning of the 20th century it has been taken up in various forms in a number of works. Examples of well-known novels from different decades and cultures are:

The booklet novel series Perry Rhodan shifts levels of action to the Andromeda Galaxy. For the first time at the beginning of the 100 booklet series Masters of the Island , published between 1965–1967 , the protagonist Perry Rhodan with the spaceship he commands first comes near the Andromeda Galaxy, which cannot be reached by spaceship propulsion, through a "transmitter" and then penetrates later into the galaxy itself.
The novel The Girl from Space by the Russian author Ivan Yefremow from 1958 and its film adaptation locates the origin of an unknown spaceship that was incidentally found on a planet and which is to be investigated in the future, at the end of the novel in the Andromeda Nebula, to which it was previously unable to connect due to the distance
In the novel Mutants on Andromeda by Klaus Frühauf, an earthly expedition travels to the Andromeda Galaxy and has an adventure there. The novel gained fame through a preprint in 1974 in the then high-circulation Berliner Zeitung .
In the novel Nebel der Andromeda - The Strange Legacy of an Earthly by Fritz Brehmer , published in 1920, the protagonist teleports himself to an earth-like planet of the Andromeda nebula with a further developed civilization, where he then finds his love. The novel also takes up the discovery of the Andromeda nebula by Simon Marius and the distance estimate by Julius Scheiner.

Well-known representatives of other genres are:

In the comic series Superman , which began in 1938, Superman's birth planet is in the miniseries Superman: Birthright , published in 2004 - in contrast to the earlier depiction - in the Andromeda Galaxy.
A power attacking the earth in the anime Uchū Senkan Yamato 2 comes from the Andromeda Galaxy.
In the episode Stone and Dust of the television series Starship Enterprise , the Enterprise is captured by aliens from the Andromeda Galaxy who want to return there. Even with the help of the spaceship's fictional propulsion technology, it would take 300 years to reach it from the Milky Way.
The computer game Mass Effect: Andromeda is set in the Andromeda Galaxy, which, according to prehistory, is reached by 4 spaceships after a journey of around 600 years from the Milky Way.

Web links

Commons : Andromeda Galaxy - Collection of Images, Videos, and Audio Files

Wiktionary: Andromeda Galaxy - explanations of meanings, word origins, synonyms, translations

Stefan Karge : The Great Andromeda Nebula on YouTube , accessed on July 30, 2020. Lecture - Physikalischer Verein , Frankfurt Observatory.
Florian Freistetter : Star Stories, Episode 208: The Andromeda Galaxy. In ScienceBlogs . Podcast and transcription with illustrations.
Roland Rosenbauer : The Andromeda Nebula. At: What is what .
Hartmut Frommert, Christine Kronberg: M 31. In: SEDS . Retrieved August 8, 2020

Databases with around 10,000 research reports (as of 2020) on or with reference to the Andromeda Galaxy:

Astrophysics Data System : M31.
SIMBAD : M31.

literature

General

Paul Hodge : The Andromeda Galaxy (= Astrophysics and space science library . No. 176 ). Kluwer Academic Publishers, Dordrecht / Boston / London 1992, ISBN 0-7923-1654-1 , doi : 10.1007 / 978-94-015-8056-4 ( limited preview in Google book search).
Sidney van den Bergh : The Andromeda galaxy (M31) . In: The Galaxies of the Local Group (= Cambridge Astrophysics . No. 35 ). Cambridge University Press, Cambridge 2000, ISBN 0-521-75810-6 , pp. 9–46 , doi : 10.1017 / CBO9780511546051.004 ( limited preview in Google Book search).
René Walterbos : Andromeda Galaxy . In: Paul Murdin (Ed.): Encyclopedia of Astronomy and Astrophysics . Nature Publishing Group , 2001 ( crcpress.com [PDF; 119 kB ]).

Sub-areas

Charli M. Sakari : The Globular Star Clusters of the Andromeda Galaxy . Morgan & Claypool Publishers, Bristol 2019, ISBN 978-1-64327-750-9 , doi : 10.1088 / 2053-2571 / ab39de ( limited preview in Google book search).
Annette MN Ferguson , AD Mackey : Substructure and Tidal Streams in the Andromeda Galaxy and its Satellites . In: Tidal Streams in the Local Group and Beyond (= Astrophysics and Space Science Library . No. 420 ). 2016, ISBN 978-3-319-19335-9 , bibcode : 2016ASSL..420..191F .
Elly M. Berkhuijsen , Rainer Beck , René AM Walterbos (Eds.): The interstellar medium in M31 and M33 (= WE-Heraeus-Seminar Physikzentrum Bad Honnef . No. 232 ). Shaker, Aachen 2000 ( harvard.edu ).
Ken Freeman : M31: The Old Stellar Populations . In: Paul Murdin (Ed.): Encyclopedia of Astronomy and Astrophysics . Nature Publishing Group, 2001 ( crcpress.com [PDF; 50 kB ]).

Individual evidence

↑ ^a ^b ^c ^d ^e NGC 224. In: NASA / IPAC EXTRAGALACTIC DATABASE. August 22, 2007, accessed September 28, 2019 .

↑ ^a ^b ^c ^d SEDS : NGC 224

↑ Gerard de Vaucouleurs, Antoinette de Vaucouleurs , Herold G. Corwin, Jr., Ronald J. Buta, Georges Paturel, Pascal Fouque: Third Reference Catalog of Bright Galaxies . Springer, New York, NY (USA) 1991, ISBN 0-387-97552-7 , pp. 2091 , bibcode : 1991rc3..book ..... D ( u-strasbg.fr ).

↑ ^a ^b ^c Andromeda Galaxy is easier than expected. The Milky Way and its neighbor have almost the same mass. In: scinexx.de. MMCD NEW MEDIA GmbH, February 15, 2018, accessed on June 23, 2020 . Prajwal R. Kafle, Sanjib Sharma, Geraint F. Lewis, Aaron SG Robotham, Simon P. Driver: The need for speed: Escape velocity and dynamical mass measurements of the Andromeda galaxy . In: Monthly Notices of the Royal Astronomical Society . tape
475 , no. 3 , 2018, p. 4043–4054 , bibcode : 2018MNRAS.475.4043K .
↑ ^a ^b Sidney van den Bergh : The Stellar Populations of M31 . In: Publications of the Astronomical Society of the Pacific . Vol. 103, 1991, pp. 1053-1068 , doi : 10.1086 / 132925 , bibcode : 1991PASP..103.1053V .
↑ ^a ^b Karoline M. Gilbert, Puragra Guhathakurta , Rachael L. Beaton, James Bullock , Marla C. Geha , Jason S. Kalirai, Evan N. Kirby , Steven R. Majewski , James C. Ostheimer, Richard J. Patterson, Erik J. Tollerud, Mikito Tanaka , Masashi Chiba : Global Properties of M31's Stellar Halo from the SPLASH Survey. I. Surface Brightness Profile . In: Astrophysical Journal . tape 760 , no. 1 , 2012, p. 21 , bibcode : 2012ApJ ... 760 ... 76G .
↑ Laura L. Watkins, N. Wyn Evans, Jin H. An: The masses of the Milky Way and Andromeda galaxies . In: Monthly Notices of the Royal Astronomical Society . tape 406 , no. 1 , 2010, p. 264-278 , bibcode : 2010MNRAS.406..264W .
^ ^A ^b Jonathan Sick, Stephane Courteau, Jean-Charles Cuillandre, Julianne Dalcanton , Roelof de Jong, Michael McDonald, Dana Simard, R. Brent Tully : The Stellar Mass of M31 as inferred by the Andromeda Optical & Infrared Disk Survey . In: Galaxy Masses as Constraints of Formation Models, Proceedings of the International Astronomical Union, IAU Symposium . tape 311 , 2015, p. 82–85 , bibcode : 2015IAUS..311 ... 82S .
↑ ^a ^b A. Tamm, E. Tempel, P. Tenjes, O. Tihhonova, T. Tuvikene: Stellar mass map and dark matter distribution in M 31 . In: Astronomy & Astrophysics . tape 546 , 2012, p. 11 , bibcode : 2012A & A ... 546A ... 4T .
^ Annette Ferguson: The Stellar Populations (in the Outskirts) of M31. (PDF; 2.5 MB) In: esa.int . Retrieved September 4, 2020 .
↑ Ivan Debono: The earliest image of another galaxy. In: idebono.eu. Retrieved May 7, 2018 .
^ Charles Messier: Catalog des Nébuleuses et Amas d'Étoiles . In: Connoissance des temps ,… Pour l'Année bissextile 1784 . Paris 1781 ( bnf.fr ).
↑ Simon Marius: Mundus Iovialis - The world of Jupiter . Ed .: Joachim Schlör. Schrenk-Verlag, Gunzenhausen 1988, p. 45 ( The Andromeda Nebula. ( Memento from September 5, 2014 in the Internet Archive )
Digitized version of the original, Munich Digitization Center, see p. 19. - Original title: Mundus Iovialis . Norimberga 1614.).
^ William Derham : Observations of the Appearances among the Fix'd Stars, Called Nebulous Stars . In: Philosophical Transactions of the Royal Society . tape 38 , 1733, pp. 70-74 , bibcode : 1733RSPT ... 38 ... 70D , JSTOR : 103819 .
↑ Immanuel Kant : General natural history and theory of heaven . Johann Friederich Petersen, Königsberg / Leipzig 1755, p. XLII ( digital full-text edition at Wikisource , version from May 12, 2016).
↑ Immanuel Kant: General natural history and theory of heaven . Johann Friederich Petersen, Königsberg / Leipzig 1755, p. 103 ( digital full-text edition at Wikisource , version from May 12, 2016).
^ W. Herschel : On the Construction of the Heavens . In: Philosophical Transactions of the Royal Society of London . tape 75 , no. 0 , 1785, p. 213-266 , bibcode : 1785RSPT ... 75..213H . , see pages 247 and 262.
↑ ^a ^b M. Hoskin: The Cosmology of William Herschel . In: ASP Conference Series . tape 409 , August 2009, p. 91-99 , bibcode : 2009ASPC..409 ... 91H .
^ William Herschel: Astronomical Observations Relating to the Sidereal Part of the Heavens, and Its Connection with the Nebulous Part; Arranged for the Purpose of a Critical Examination . In: Philosophical Transactions of the Royal Society of London . tape 104 , 1814, pp. 248-284 , bibcode : 1814RSPT..104..248H . See p. 260, Connoissance 31 = Messier 31.
↑ ^a ^b Scheiner: The spectrum of the Andromeda nebula and its relationship to our fixed star system . In: Heaven and Earth . 1899, p. 325-328 ( archive.org ).
↑ Le Gentil : Remarques sur les Étoiles Nebuleuses . In: Histoire de l'Académie royale des sciences ... avec les mémoires de mathématique & de physique . Année M.DCCLIX. Paris 1765, p. 453-471 + Pl. 21 . ( Digitized on Gallica ).
^ Thomas William Webb : The Great Nebula in Andromeda . In: Nature . tape 25 , no. 641 , 1882, pp. 341–345 , bibcode : 1882Natur..25..341W .
^ William Huggins , WF Denning : The New Star in Andromeda . In: Nature . tape 32 , no. 829 , 1885, pp. 465–466 , bibcode : 1885Natur..32..465H .
^ ^A ^b H. C. Wilson : The Great Nebula in Andromeda . In: Popular Astronomy . tape 7 , 1899, pp. 507-510 , bibcode : 1899PA ...... 7..507W .
↑ Isaac Roberts: Photographs of the nebulæ M 31, h 44, and h 51 Andromedæ, and M 27 Vulpeculæ . In: Monthly Notices of the Royal Astronomical Society . tape 49 , 1888, pp. 65-66 , bibcode : 1888MNRAS..49 ... 65R .
^ ^A ^b J. H. Reynolds : The light curve of the Andromeda nebula (NGC 224) . In: Monthly Notices of the Royal Astronomical Society . tape 74 , 1913, pp. 132-136 , bibcode : 1913MNRAS..74..132R .
^ ^A ^b Arthur Stanley Eddington : Stellar movements and the structure of the universe . London 1914 ( archive.org ).
↑ Stephen Alexander : On the origin of the forms and the present condition of some of the clusters of stars, and several of the nebulae . In: Astronomical Journal . tape 2 , no. 38 , 1852, pp. 105–111 , bibcode : 1852AJ ...... 2..105A .
↑ ^a ^b ^c J. Scheiner : About the spectrum of the Andromeda nebula . In: Astronomical News . tape 148 , 1899, pp. 325–328 , bibcode : 1899AN .... 148..325S .
↑ E. Hartwig : About the new star in the great Andromeda nebula . In: Astronomical News . tape 112 , 1885, p. 355-360 , bibcode : 1885AN .... 112..355H .
^ William Huggins : On the Spectra of Some of the Nebulae . In: Philosophical Transactions of the Royal Society of London . tape 154 , no. 0 , 1864, p. 437–444 , doi : 10.1098 / rstl.1864.0013 , bibcode : 1864RSPT..154..437H .
^ William Huggins: Further Observations on the Spectra of Some of the Nebulae, with a Mode of Determining the Brightness of These Bodies . In: Philosophical Transactions of the Royal Society of London . tape 156 , 1866, pp. 381-397 , bibcode : 1866RSPT..156..381H .
↑ VM Slipher : The radial velocity of the Andromeda Nebula . In: Lowell Observatory Bulletin . tape 1 , 1913, pp. 56-57 , bibcode : 1913LowOB ... 2 ... 56P .
^ ^A ^b Stéphane Courteau , Sidney van den Bergh : The Solar Motion Relative to the Local Group . In: Astronomical Journal . tape 118 , no. 1 , 1999, p. 337-345 , bibcode : 1999AJ .... 118..337C .
^ Mario L. Mateo : Dwarf Galaxies of the Local Group . In: Annual Review of Astronomy and Astrophysics . tape 36 , 1998, pp. 435–506 , bibcode : 1998ARA & A..36..435M .
↑ VM Slipher: The detection of nebular rotation . In: Lowell Observatory Bulletin . tape 2 , 1914, p. 66 , bibcode : 1914LowOB ... 2 ... 66S .
^ VM Slipher: Nebulae . In: Proceedings of the American Philosophical Society . tape 56 , 1917, pp. 403-409 , bibcode : 1917PAPhS..56..403S .
^ FG Pease : The Rotation and Radial Velocity of the Central Part of the Andromeda Nebula . In: Proceedings of the National Academy of Sciences of the United States of America . tape 4 , no. 1 , 1918, p. 21-24 , bibcode : 1918PNAS .... 4 ... 21P .
↑ J. Scheiner: The construction of the universe . Leipzig 1900, p. 126 ( google.de ).
↑ P. Götz : Studies on the Andromeda Nebula . In: Publications of the Astrophysical Institute Koenigstuhl-Heidelberg . tape 3 , p. 1–39 , bibcode : 1906PAIKH ... 3 .... 1G .
↑ ^a ^b Felix Linke: Andromeda Nebula . In: nature . No. 5 , 1914, pp. 103-106 ( archive.org ).
^ Heber D. Curtis : Novae in Spiral Nebulae and the Island Universe Theory . In: Publications of the Astronomical Society of the Pacific . tape 29 , no. 171 , 1917, pp. 206-207 , bibcode : 1917PASP ... 29..206C .
↑ Harlow Shapley : Note on the Magnitudes of Novae in Spiral Nebulae . In: Publications of the Astronomical Society of the Pacific . tape 29 , no. 171 , 1917, pp. 213 , bibcode : 1917PASP ... 29R.213S .
^ Sarah Loff: Hubble's High-Definition Panoramic View of the Andromeda Galaxy. February 24, 2015, accessed January 9, 2019 .
↑ C. Luplau-Janssen, GEH Haarh: The parallax of the Andromeda nebula . In: Astronomical News . tape 215 , 1922, pp. 285 , bibcode : 1922AN .... 215..285L .
↑ ^a ^b ^c E. Oepik : An estimate of the distance of the Andromeda Nebula . In: Astrophysical Journal . tape 55 , 1922, pp. 406-410 , bibcode : 1922ApJ .... 55..406O .
↑ Götz Hoeppe: Beyond the Milky Way . In: Stars and Space . No. 10 , 2003, p. 34-39 ( Spektrum.de ).
↑ ^a ^b ^c ^d Edwin Hubble: A spiral nebula as a stellar system, Messier 31 . In: Astrophysical Journal . tape 69 , 1929, pp. 103-158 , bibcode : 1929ApJ .... 69..103H .
↑ ^a ^b Friedrich Gondolatsch : The astronomical distance scale . In: Physical sheets . tape 12 , no. 7 , 1956 ( wiley.com [PDF]).
↑ Original documents, explanations:
Hubble's Famous M31 VAR! plate. In: Carnegie Institution for Science . Retrieved June 6, 2020 . Snapshots of the star that changed the universe. In: European Southern Observatory . Retrieved June 6, 2020 .
^ Walter Baade, Fritz Zwicky : On Super-novae . In: Contributions from the Mount Wilson Observatory . tape 3 , 1934, pp. 73–78 , bibcode : 1934CoMtW ... 3 ... 73B . Walter Baade, Fritz Zwicky: Cosmic Rays from Super-novae . In: Contributions from the Mount Wilson Observatory . tape
3 , 1934, pp. 79–83 , bibcode : 1934CoMtW ... 3 ... 79B .
^ ^A ^b W. Baade: The Period-Luminosity Relation of the Cepheids . In: Publications of the Astronomical Society of the Pacific . tape 68 , no. 400 , 1956, pp. 5 , bibcode : 1956PASP ... 68 .... 5B .
↑ Nick Allen: The Cepheid Distance Scale: A History - Section 2: The Great Debate and the Great Mistake: Shapley, Hubble, Baade. Retrieved June 6, 2020 .
↑ Jeremy Mold , Jerome Kristian : The Stellar Population in the Halos of M31 and M33 . In: Astrophysical Journal . tape 305 , 1986, pp. 591 , bibcode : 1986ApJ ... 305..591M .
↑ Christopher J. Pritchet , Sidney van den Bergh: Observations of RR Lyrae Stars in the Halo of M31 . In: Astrophysical Journal . tape 316 , 1987, pp. 517 , bibcode : 1987ApJ ... 316..517P .
↑ KZ Stanek , PM Garnavich : Distance to M31 with the Hubble Space Telescope and Hipparcos Red Clump Stars . In: Astrophysical Journal . tape 503 , no. 2 , 1998, p. L131-L134 , bibcode : 1998ApJ ... 503L.131S .
↑ Ignasi Ribas, Carme Jordi , Francesc Vilardell, Edward L. Fitzpatrick , Ron W. Hilditch, Edward F. Guinan : First Determination of the Distance and Fundamental Properties of an Eclipsing Binary in the Andromeda Galaxy . In: Astrophysical Journal . tape 635 , no. 1 , December 2005, p. L37 – L40 , bibcode : 2005ApJ ... 635L..37R .
^ R. Wagner-Kaiser, A. Sarajedini , JJ Dalcanton, BF Williams, A. Dolphin: Panchromatic Hubble Andromeda Treasury XIII: The Cepheid period-luminosity relation in M31 . In: Monthly Notices of the Royal Astronomical Society . tape 451 , 2015, p. 724–738 , bibcode : 2015MNRAS.451..724W .
↑ ^a ^b A. R. Conn, RA Ibata , GF Lewis , QA Parker , DB Zucker , NF Martin, AW McConnachie , MJ Irwin , N. Tanvir , MA Fardal, AMN Ferguson, SC Chapman , D. Valls-Gabaud : A Bayesian Approach to Locating the Red Giant Branch Tip Magnitude. II. Distances to the Satellites of M31 . In: Astrophysical Journal . tape 758 , no. 1 , 2012, p. 11.1–11.19 , bibcode : 2012ApJ ... 758 ... 11C .
^ Charles Messier : Observations Astronomiques, 1770-1774 . In: Connaissance des Temps… pour l'an IX. (1801). Paris 1798, p. 434-465 ( digitale-sammlungen.de ). (see p. 461)
↑ ^a ^b E. P. Hubble : The realm of the nebulae . Yale University Press , New Haven 1936, ISBN 978-0-300-02500-2 , pp. 77 (English).
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^ ^A ^b D. Crampton, AP Cowley, D. Schade, P. Chayer,: The M31 Globular Cluster System . In: Astrophysical Journal . tape 288 , 1985, pp. 494 , bibcode : 1985ApJ ... 288..494C .
^ Pauline Barmby , John P. Huchra : M31 Globular Clusters in the Hubble Space Telescope Archive. I. Cluster Detection and Completeness . In: Astronomical Journal . tape 122 , no. 5 , 2001, p. 2458-2468 , bibcode : 2001AJ .... 122.2458B .
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↑ AD Mackey, A. Huxor, AMN Ferguson, NR Tanvir, M. Irwin, R. Ibata, T. Bridges, RA Johnson, G. Lewis: ACS Photometry of Extended, Luminous Globular Clusters in the Outskirts of M31 . In: Astrophysical Journal . tape 653 , no. 2 , 2006, p. L105 – L108 , bibcode : 2006ApJ ... 653L.105M .
↑ ^a ^b ^c David Burstein, Yong Li, Kenneth C. Freeman, John E. Norris, Michael S. Bessell, Joss Bland-Hawthorn, Brad K. Gibson, Michael A. Beasley, Hyun-chul Lee, Beatriz Barbuy, John P. Huchra, Jean P. Brodie, Duncan A. Forbes: Globular Cluster and Galaxy Formation: M31, the Milky Way, and Implications for Globular Cluster Systems of Spiral Galaxies . In: Astrophysical Journal . tape 614 , no. 1 , 2004, p. 158–166 , bibcode : 2004ApJ ... 614..158B .
↑ Nelson Caldwell, Paul Harding, Heather Morrison, James A. Rose, Ricardo Schiavon, Jeff Kriessler: Star Clusters in M31. I. A Catalog and a Study of the Young Clusters . In: Astronomical Journal . tape 137 , no. 1 , 2009, p. 94–110 , bibcode : 2009AJ .... 137 ... 94C .
↑ Nelson Caldwell, Ricardo Schiavon, Heather Morrison, James A. Rose, Paul Harding: Star Clusters in M31. II. Old Cluster Metallicities and Ages from Hectospec Data . In: Astronomical Journal . tape 141 , no. 2 , 2011, p. 18 , bibcode : 2011AJ .... 141 ... 61C .
^ AD Mackey, AMN Ferguson, MJ Irwin, NF Martin, AP Huxor, NR Tanvir, SC Chapman, RA Ibata, GF Lewis, AW McConnachie: Deep Gemini / GMOS imaging of an extremely isolated globular cluster in the Local Group . In: Monthly Notices of the Royal Astronomical Society . tape 401 , no. 1 , 2010, p. 533-546 , bibcode : 2010MNRAS.401..533M .
↑ Nadja Podbregar: Andromeda is a "cannibal". In: scinexx.de. October 4, 2019, accessed June 6, 2020 .
↑ ^a ^b ^c Dougal Mackey, Geraint F. Lewis, Brendon J. Brewer, Annette MN Ferguson, Jovan Veljanoski, Avon P. Huxor, Michelle LM Collins, Patrick Côté, Rodrigo A. Ibata, Mike J. Irwin, Nicolas Martin, Alan W. McConnachie, Jorge Peñarrubia, Nial Tanvir, Zhen Wan: Two major accretion epochs in M31 from two distinct populations of globular clusters . In: Nature . tape 574 , no. 7776 , 2019, p. 69–71 , bibcode : 2019Natur.574 ... 69M .
^ ^A ^b André Lallemand , M. Duchesne, Merle F. Walker: The Rotation of the Nucleus of M 31 . In: Publications of the Astronomical Society of the Pacific . tape 72 , no. 425 , 1960, pp. 76 , bibcode : 1960PASP ... 72 ... 76L .
^ Hugh M. Johnson: The Nucleus of M31 . In: Astrophysical Journal . tape 133 , 1961, pp. 309 , bibcode : 1961ApJ ... 133..309J .
^ ES Light, RE Danielson, M. Schwarzschild : The nucleus of M31 . In: Astrophysical Journal . tape 194 , no. 1 , 1974, p. 257-263 , bibcode : 1974ApJ ... 194..257L .
↑ DC Morton, TX Thuan: Velocity dispersions in galaxies. III. The nucleus of M31 . In: Astrophysical Journal . tape 180 , 1973, pp. 705 , bibcode : 1973ApJ ... 180..705M .
^ RH Sanders, W. van Oosterom: The star swallowing luminosity of massive black holes in normal galactic nuclei . In: Astronomy and Astrophysics . tape 131 , 1984, pp. 267-275 , bibcode : 1984A & A ... 131..267S .
^ Alan Dressler, Douglas O. Richstone: Stellar Dynamics in the Nuclei of M31 and M32: Evidence for Massive Black Holes . In: Astrophysical Journal . tape 324 , January 1988, p. 701 , bibcode : 1988ApJ ... 324..701D .
^ John Kormendy: Evidence for a Supermassive Black Hole in the Nucleus of M31 . In: Astrophysical Journal . tape 325 , 1988, pp. 128 , bibcode : 1988ApJ ... 325..128K .
↑ Tod R. Lauer, SM Faber, Edward J. Groth, Edward J. Shaya, Bel Campbell, Arthur Code, Douglas G. Currie, William A. Baum, SP Ewald, J. Jeff Hester, Jon A. Holtzman, Jerome Kristian , Robert M. Light, C. Roger Lynds, Earl J. O'Neil, Jr., James A. Westphal: Planetary Camera Observations of the Double Nucleus of M31 . In: Astronomical Journal . tape 106 , 1993, pp. 1436 , bibcode : 1993AJ .... 106.1436L .
↑ M31. Disk of blue stars surrounds black hole. In: astronews.com. 2005, accessed January 11, 2020 . What's in the center of Andromeda? from the alpha-Centauri TV series (approx. 15 minutes). First broadcast on Mar 15. 2006. Ralf Bender, John Kormendy, Gary Bower, Richard Green, Jens Thomas, Anthony C. Danks, Theodore Gull, JB Hutchings, CL Joseph, ME Kaiser, Tod R. Lauer, Charles H. Nelson, Douglas Richstone, Donna Weistrop, Bruce Woodgate: HST STIS Spectroscopy of the Triple Nucleus of M31: Two Nested Disks in Keplerian Rotation around a Supermassive Black Hole . In: Astrophysical Journal . tape

631 , no. 1 , 2005, p. 280-300 , bibcode : 2005ApJ ... 631..280B .
↑ RB Menezes, JE Steiner, and TV Ricci: Discovery of an Hα Emitting Disk around the Supermassive Black Hole of M31 . In: Astrophysical Journal Letters . tape 762 , no. 2 , 2013, bibcode : 2013ApJ ... 762L..29M .
↑ Report on the mass of M 31. Retrieved on January 22, 2012 .
^ R. Giacconi , S. Murray, H. Gursky , E. Kellogg, E. Schreier, H. Tananbaum: The Uhuru catalog of X-ray sources . In: Astrophysical Journal . tape 178 , 1972, p. 281-308 , bibcode : 1972ApJ ... 178..281G .
↑ Michael R. Garcia, Stephen S. Murray, Francis A. Primini, William R. Forman, Jeffrey E. McClintock, Christine Jones: A First Look at the Nuclear Region of M31 with Chandra . In: Astrophysical Journal . tape 537 , no. 1 , 2000, pp. L23 – L26 , bibcode : 2000ApJ ... 537L..23G .
^ Albert KH Kong, Michael R. Garcia, Francis A. Primini, Stephen S. Murray, Rosanne Di Stefano, Jeffrey E. McClintock: X-Ray Point Sources in the Central Region of M31 as Seen by Chandra . In: The Astrophysical Journal . tape 577 , no. 2 , 2002, p. 738-756 , bibcode : 2002ApJ ... 577..738K .
↑ Zhiyuan Li, Michael R. Garcia, William R. Forman, Christine Jones, Ralph P. Kraft, Dharam V. Lal, Stephen S. Murray, Q. Daniel Wang: The Murmur of the Hidden Monster: Chandra's Decadal View of the Supermassive Black Hole in M31 . In: Astrophysical Journal Letters . tape 728 , no. 1 , 2011, p. 6 , bibcode : 2011ApJ ... 728L..10L .
^ Anne-Laure Melchior, Françoise Combes: Exhaustion of the gas next to the supermassive black hole of M31 . In: Astronomy & Astrophysics . tape 607 , 2017, p. 4 , bibcode : 2017A & A ... 607L ... 7M .
↑ Shuinai Zhang, Q. Daniel Wang, Adam R. Foster, Wei Sun, Zhiyuan Li, Li Ji: XMM-Newton RGS Spectroscopy of the M31 Bulge. I. Evidence for a Past AGN Half a Million Years Ago . In: Astrophysical Journal . tape 885 , no. 2 , 2019, p. 19 , bibcode : 2019ApJ ... 885..157Z .
↑ Timothy Weinzirl: Probing Galaxy Evolution by Unveiling the Structure of Massive Galaxies Across Cosmic Time and in Diverse Environments . Springer, 2014, p. 236 ( limited preview in Google Book search). See p. 6.
↑ The Milky Way once had a "brother". In: scinexx.de. Retrieved June 6, 2020 .
↑ Richard D'Souza, Eric F. Bell: The Andromeda galaxy's most important merger about 2 billion years ago as M32's likely progenitor . In: Nature Astronomy . tape 2 , 2018, p. 737–743 , bibcode : 2018NatAs ... 2..737D .
↑ Kenji Bekki: Formation of a giant HI bridge between M31 and M33 from their tidal interaction . In: Monthly Notices of the Royal Astronomical Society: Letters . tape 390 , no. 1 , 2008, p. L24 – L28 , bibcode : 2008MNRAS.390L..24B .
^ Gaia clocks new speeds for Milky Way-Andromeda collision. Retrieved June 6, 2020 .
↑ MA Fardal, A. Babul, JJ Geehan, P. Guhathakurta: Investigating the Andromeda stream - II orbital fits and properties of the progenitor. . In: Monthly Notices of the Royal Astronomical Society . tape 366 , no. 3 , 2006, p. 1012-1028 , bibcode : 2006MNRAS.366.1012F .
^ Francois Hammer, YB Yang, JL Wang, R. Ibata, H. Flores, M. Puech: A 2-3 billion year old major merger paradigm for the Andromeda galaxy and its outskirts . In: Monthly Notices of the Royal Astronomical Society . tape 475 , no. 2 , 2018, p. 2754–2767 , bibcode : 2018MNRAS.475.2754H .
↑ Has the Milky Way collided? In: scinexx.de. Retrieved June 6, 2020 .
↑ H. Zhao, B. Famaey, F. Lüghausen, P. Kroupa: Local Group timing in Milgromian dynamics. A past Milky Way-Andromeda encounter at z> 0.8 . In: Astronomy & Astrophysics . tape 557 , 2013, p. 4 , bibcode : 2013A & A ... 557L ... 3Z .
↑ Find and photograph the Andromeda galaxy in the sky on YouTube .
↑ ^a ^b ^c ^d ^e Bernd Koch, Stefan Korth: The Messier objects: The 110 classic goals for sky observers . Kosmos, Stuttgart 2010, ISBN 978-3-440-11743-9 , pp. 213 . See p. 66.
^ ^A ^b Ronald Stoyan , Stefan Binnewies, Susanne Friedrich: Atlas of the Messier objects . Erlangen 2006, ISBN 978-3-938469-07-1 , pp. 368 . Here pp. 148–149.
↑ Observing M 31, the Andromeda Galaxy: My Observing log entries of M 31 & What to expect when observing M 31. In: backyard-astro.com. Retrieved January 29, 2020 .
↑ The observation. In: andromedagalaxie.de. Retrieved September 26, 2020 .
^ Herbert Wallner: Mosaic of the Andromeda Galaxy. In: Spektrum.de . Retrieved August 8, 2020 .
↑ Arno Rottal: Andromeda Galaxy with IFN. In: Spektrum.de. Retrieved August 8, 2020 .
^ Christian Koll: Andromeda. In: Spektrum.de. Retrieved August 8, 2020 .
↑ Amir H. Abolfath: M31: The Andromeda Galaxy. In: Astronomy Picture of the Day . Retrieved August 8, 2020 .
↑ Stefan Karge : The Great Andromeda Nebula on YouTube , accessed on July 30, 2020. Lecture - Physikalischer Verein , Frankfurt Observatory.
↑ M 31 Determination of distance using Cepheids. In: Spektrum.de. Retrieved August 8, 2020 .
↑ William Herschel: On the construction of heaven . Königsberg 1791, p. 109-110, 130-131 ( google.de ).
↑ Examples in the period 1770–1840:
Johann Elert Bode : Clear instructions for knowing the starry sky . Hamburg 1772, p. 294 ( google.de ). Johann Christoph Möller: Attempt of a textbook of astronomy for elementary schools . Altona 1817, p.
33-34 ( google.de ). Gotthilf Heinrich von Schubert : The primeval world and the fixed stars . Dresden 1822, p.
133 ( google.de ). Joseph Johann von Littrow : The miracles of heaven or common understanding of the world system . tape
2 . Stuttgart 1835, p. 382 ( google.de ). Johann Andreas Lebrecht Richter: Handbook of popular astronomy for the educated classes . Quedlinburg / Leipzig 1840, p.
671-672 ( google.de ).
↑ Examples are:
Mathematics . In: Allgemeine Literatur-Zeitung . No. 82 , 1799, pp. 649-656 ( digitale-sammlungen.de ). Mixed messages . In: State and learned newspaper of the Hamburg impartial correspondent . No.
192 , 1805, pp. 6 ( Digitale-sammlungen.de ). Math . In: Allgemeine Literatur-Zeitung . No.
255 , 1818, pp. 342–344 ( digital-sammlungen.de ). Astronomy . In: literature sheet . No.
49 , 1822, pp. 194–196 ( Digitale-sammlungen.de ). Math . In: Supplementary sheets to the Allgemeine Literatur-Zeitung . No.
65 , 1825, pp. 513-520 ( digital-sammlungen.de ). Various things from heaven . In: Morgenblatt for educated stands . No.
26 , 1834, pp. 101-102 ( Digitale-sammlungen.de ). Halley's Comet . In: The Bavarian Landbote . No.
278 , 1835, pp. 1191 ( Digitale-sammlungen.de ).
↑ From heaven . In: Illustrated entertainment sheet, Sunday supplement to the Schweinfurter Anzeiger . No. 16 , 1874, pp. 127–128 ( Digitale-sammlungen.de ).
↑ Andromeda . In: The large conversation lexicon for the educated stands . 2nd volume (Alexandria - Angora). Hildburghausen / Amsterdam / Paris / Philadelphia 1841, p. 955 ( Digitale-sammlungen.de ).
↑ Examples are:
Miscellaneous: The Andromeda Nebula . In: Allgemeine Zeitung . No. 249 , 1885, pp. 3669-3670 ( digitale-sammlungen.de ). Miscellaneous: Astronomical . In: Allgemeine Zeitung . No.
351 , 1885, pp. 5182 ( Digitale-sammlungen.de ). A. Kopff : The Andromeda Nebula . In: Supplement to the Allgemeine Zeitung . No.
23 , 1908, pp. 180–181 ( Digitale-sammlungen.de ).
^ Wilhelm Heß: Ule, Otto Eduard Vincenz . In: Allgemeine Deutsche Biographie, published by the Historical Commission at the Bavarian Academy of Sciences . tape 39 , 1895, p. 180–181 ( digital full-text edition in Wikisource ).
↑ Otto Ule : Changeable and New Stars . In: Nature . 1868, p. 281-284 ( handle.net ).
↑ Fog . In: Meyers Großes Konversations-Lexikon . 14th band (Mittewald – Ohmgelb). Leipzig / Vienna 1906, p. 482-484, panel I ( archive.org ).
↑ A. Kopff : The Andromeda Nebula . In: Supplement to the Allgemeine Zeitung . No. 23 , 1908, pp. 180–181 ( Digitale-sammlungen.de ).
^ Fritz Kahn : The Milky Way . Ed .: Kosmos Society for Friends of Nature . Stuttgart 1914 ( archive.org , gutenberg.org ).
↑ A. v. Weinberg : The Origin of the Inorganic World . In: From nature and museum . tape 53 , 1922, pp. 49-71 ( archive.org ).
↑ Scientific review . Determining the distances of star clusters and nebulae. In: Our world . tape 22 , no. 2 , 1930, p. 56 ( google.de ).
↑ U. Bernt: The flight of the worlds . In: Our world . tape 29 , no. 3 , 1937, pp. 80-82 ( google.de ).
^ Paul Kirchberger : Novae and Supernovae . In: Our world . tape 30 , no. 4 , 1938, pp. 113–117 ( google.de ).
↑ Nebulae . In: Brockhaus Handbook of Knowledge in 4 volumes . 3rd volume (L-R). Leipzig 1923, p. 349 ( google.de ).
↑ Fog . In: Meyer's Lexicon . 7th edition. 8th volume (Marut – Oncidium), 1928, Sp. 1096–1098, plate “Nebulae”, 5th Andromeda Nebula .
↑ The so-called "nebulae", in reality enormous worlds of stars . In: Kosmos . 1938, p. 319 ( google.de ).
↑ Claus Oesterwinter: The Andromeda Nebula - a star system . In: Kosmos . No. 2 , 1951, p. 81-86 .
↑ ^a ^b Berthold Lammert: Error in the universe. In: The time . 1953, accessed August 8, 2020 .
↑ Examples are:
Hermann J. Klein : Further observations about the new star in Andromeda nebula a. Compilation of the results . In: Sirius . 1885, p. 241–247, 285 ( archive.org - scan incomplete ). FK Ginzel : The Nova in Andromeda . In: Sirius . 1885, p.
273-274 ( archive.org ). The great fog in the Andromeda . In: Sirius . 1885, p.
274-277 ( archive.org ). The spectrum of the new star in Andromeda . In: Sirius . 1886, p.
46 ( archive.org ). Notes on the New Star in the Andromeda Nebula . In: Sirius . 1886, p.
59-61 ( archive.org ). The flashing of new stars with particular reference to the nova in Andromeda . In: Sirius . 1886, p.
89-91 ( archive.org ). The photographs of the great Andromeda Nebula by Mr. Isaak Roberts . In: Sirius . 1889, p.
49-51, panel III ( archive.org ). Across the spectrum of the Andromeda Nebula . In: Sirius . 1899, p.
111-112 ( archive.org ). The rotational and radial speed of the Andromeda Nebula . In: Sirius . 1922, p.
116 ( archive.org ).
↑ W. Kruse: The spiral nebula . In: The universe . tape 24 , no. 8 , 1925, pp. 157–165 ( astw.de [PDF]).
^ W. Kruse: Globular clusters in spiral nebulae . In: The universe . tape 32 , issue 1, 1932, p. 1–3 ( astw.de [PDF]).
↑ Cheerful . In: The Stars . 1924, p. 61-62 ( archive.org ).
^ GA Richter : Size and spiral structure of the Andromeda nebula . In: The Stars . 1971, p. 173-182 .
↑ Examples are: The
spiral structure of the Andromeda nebula (M 31) . In: Stars and Space . 1965, p. 8-10 . Johannes V. Feitzinger : The Andromeda Nebula . In: Stars and Space . 1998, p.
320-325 . Götz Hoeppe: Beyond the Milky Way . In: Stars and Space . No.
10 , 2003, p. 34-39 ( Spektrum.de ). Sydney van den Bergh: Star Populations and the Evolution of the Andromeda Galaxy . In: Stars and Space . 2003, p.
40-46 . Rainer Beck, Elly M. Berkhuijsen: Huge magnetic fields pervade the Andromeda Galaxy . In: Stars and Space . June, 2020, p.
20−22 ( Spektrum.de , manuscript ).
↑ Examples are:
M31. Disk of blue stars surrounds black hole. In: astronews.com. 2005, accessed January 11, 2020 . Andromeda Adrift in Sea of Dust in New Spitzer Image. In: Harvard-Smithsonian Center for Astrophysics . Retrieved August 8, 2020 . Cold gas in the Andromeda Galaxy. In: Max Planck Society . Retrieved June 6, 2020 . Rainer Kayser: Even bigger than expected. In: astronews.com. January 9, 2007, accessed June 5, 2020 . Galactic cannibalism exposed. In: astronews.com. September 3, 2009, accessed May 30, 2020 . Andromeda Galaxy eats its neighbors. In: scinexx.de. Retrieved June 6, 2020 . Hubble's Famous M31 VAR! plate. In: Carnegie Institution for Science . Retrieved June 6, 2020 . Snapshots of the star that changed the universe. In: European Southern Observatory . Retrieved June 6, 2020 . Report on the mass of M 31. In: Space Telescope Science Institute . Retrieved January 22, 2012 . Hubble Finds Giant Halo Around the Andromeda Galaxy. In: Space Telescope Science Institute. Retrieved June 6, 2020 . Sarah Loff: Hubble's High-Definition Panoramic View of the Andromeda Galaxy. In: NASA . February 24, 2015, accessed January 9, 2019 . Andromeda Galaxy is easier than expected. The Milky Way and its neighbor have almost the same mass. In: scinexx.de. MMCD NEW MEDIA GmbH, February 15, 2018, accessed on June 23, 2020 . Nadja Podbregar: Andromeda is a “cannibal”. In: scinexx.de. October 4, 2019, accessed June 6, 2020 . The Milky Way once had a "brother". In: scinexx.de. Retrieved June 6, 2020 . Has the Milky Way collided? In: scinexx.de. Retrieved June 6, 2020 .
↑ Examples are:
Andromeda galaxy - neighbor, why do you have such a big cap? In: Der Spiegel . 2015, accessed August 8, 2020 . Record image from the “Hubble” telescope. My god it's full of stars! In: Der Spiegel. 2015, accessed August 8, 2020 . Andromeda Galaxy - Astronomers are spying on beautiful neighbor. In: Der Spiegel. 2011, accessed August 8, 2020 .
↑ Examples are:
Many globular clusters around the Andromeda nebula. In: Frankfurter Allgemeine Zeitung . 1993, accessed September 25, 2020 . Galaxies. The universe is full of monsters. In: Frankfurter Allgemeine Zeitung. 2006, accessed August 8, 2020 . Hermann Michael Hahn : Andromeda Nebula. Portraits for the cosmic poetry album. In: Frankfurter Allgemeine Zeitung. 2011, accessed August 8, 2020 .
↑ Andromeda Galaxy: The Cosmic Cannibal. In: Süddeutsche Zeitung . 2010, accessed August 8, 2020 .
↑ Niels Boeing: A ghost lives in the cosmos. In: The time. 2016, accessed August 8, 2020 .
↑ Examples are:
Look into the heart of the Andromeda galaxy. In: Neue Zürcher Zeitung . 2005, accessed September 9, 2020 . The Andromeda Galaxy - a cosmic cannibal. In: Neue Zürcher Zeitung. 2009, accessed September 9, 2020 . A new home for the sun. In: Neue Zürcher Zeitung. 2007, accessed September 9, 2020 .
↑ The collision of the Milky Way and the Andromeda Galaxy has actually already begun . In: The Standard . 2020 ( derstandard.de ).
↑ Examples are:
J. Scheiner: The construction of the universe . Leipzig 1900 ( google.de ). See preface.
A. v. Weinberg: The Origin of the Inorganic World . In: From nature and museum . tape 53 , 1922, pp. 49-71 ( archive.org ). What's in the center of Andromeda? from the alpha-Centauri TV series (approx. 15 minutes). First broadcast on Mar 15. 2006. Stefan Karge : The Great Andromeda Nebula on YouTube , accessed on July 30, 2020. Lecture - Physikalischer Verein , Frankfurt Observatory. Florian Freistetter : Star Stories Episode 208: The Andromeda Galaxy , podcast and transcription with images, 2016. Find and photograph the Andromeda galaxy in the sky on YouTube .

↑ Erich Übelacker : Our cosmos . In: What is what . tape 102 , 1999, pp. 39 ( google.de ).

↑ Manfred Baur: Universe . In: What is what . tape 102 , 2015, p. 8-9, 18-19 .

^ Andromeda, Astronomy. In: zazzle.com. Retrieved August 8, 2020 .

↑ For example:
Bhushita: Galaxy Art with Oil Pastels | Andromeda Galaxy drawing Step by step - for Beginners on YouTube .
Andromeda Galaxy Painting / Acrylic painting / Beginner / Tutorial on YouTube .
Jake Daurham: Painting Andromeda with Acrylic | Time Lapse on YouTube .
Maria Racynska: Watercolor Andromeda Galaxy Painting Demonstration on YouTube .
Lanchen: Watercolor Wednesday Andromeda Galaxy Tutorial by “Lanchen Designs” on YouTube .

^ Postage stamp 15 Pfennig, 1967: Leipzig Spring Fair, 2-meter universal reflecting telescope - Andromeda galaxy, M 32 and NGC 205 in the background. In: stampcommunity.org. Retrieved August 8, 2020 .

^ Stamp ›Andromeda Galaxy and telescope, Barbados, 1988. In: colnect.com. Retrieved August 8, 2020 .

^ Stamp ›Halley's Comet and Andromeda Galaxy, Mali, 1996. In: colnect.com. Retrieved August 8, 2020 .

^ Stamp ›Andromeda Galaxy, Germany, Federal Republic, 1999. In: colnect.com. Retrieved August 8, 2020 .

^ Stamp ›Astronomy - Andromeda, Indonesia, 2003. In: colnect.com. Retrieved August 8, 2020 .

↑ Bolivian postage stamp 100 Boliviano, 2014: Galileo Galilei 450 años de su nacimiento. In: stampcommunity.org. Retrieved August 8, 2020 .

^ Stamps :: Bangladesh, International Year of Astronomy Sheetlet, 2009. In: mediabd.com. Retrieved August 8, 2020 .

^ Bulgarian stamps 0.60 leva and 1.50 leva, 2009: IC 342 and M 31. In: stampcommunity.org. Retrieved August 8, 2020 .

↑ Estonian postage stamps € 0.58, 2009: Universumi Kärgstruktuuri avastas Jaan Einasto / Cell Structure of the Universum was discovered by Jaan Einasto - second stamp shows the Andromeda Galaxy. In: stampcommunity.org. Retrieved August 8, 2020 .

↑ French postage stamps € 0.70, 2009: SATURNE - in the background Horsehead Nebula and Andromeda Galaxy - and EXOPLANET. In: stampcommunity.org. Retrieved August 8, 2020 .

↑ North Cypriot stamps 80 Kuruş, 2009 - Comet, Andromeda Galaxy and Sun with the planets Mercury ... Neptune. In: stampcommunity.org. Retrieved August 8, 2020 .

^ Turkish postage stamps 80 Kuruş and 1 Lira, 2009: CACABEY Gökbilim medresesi. (1272) Kırşehir - Andromeda Galaxy in the background - ALI KUŞÇU (1403–1474) Gökbilimci - Earth in the background. In: stampcommunity.org. Retrieved August 8, 2020 .

^ KH Scheer , Clark Darlton : Perry Rhodan: The road to Andromeda . tape 200 . Hamburg 1965, chap. 5 .

^ William Voltz - KH Scheer, Clark Darlton: Perry Rhodan: The world of the regenerated . tape 252 . Hamburg 1966, chap. 1-4.

^ IA Yefremov : The girl from space . Berlin 1958, p. 269-272 .

↑ Klaus Frühauf : Mutants on Andromeda . Berlin 1980, p. 5 ff .

↑ Mutants on Andromeda. In: lifeinthe22ndcentury.de. Retrieved August 8, 2020 .

↑ Fritz Brehmer: Nebel der Andromeda - The strange legacy of an earthly . Leipzig 1920, p. 56-59, 69, 78, 112-148, 154 ff . ( gutenberg.org ).

↑ Fritz Brehmer: Nebel der Andromeda - The strange legacy of an earthly . Leipzig 1920, p. 74-75 ( gutenberg.org ).

↑ Reinhard Barby : The astronomy in modern literature . In: Sirius . 1921, p. 132-143 ( archive.org ).

↑ Mark Waid , Leinil Francis Yu, Gerry Alanguilan, Dave Mccaig: Superman: Birthright . Burbank (California) 2004, ISBN 978-1-4012-0252-1 , pp. 212 .

↑ Patrulha Estelar - 05 Cometa Império on YouTube (Japanese, Portuguese subtitles).

↑ Episode 5 Commentary. Retrieved September 9, 2020 .

↑ 30 years of Star Trek. Official special edition for collectors . Telemedia Communications, North York, Ontario 1996, p. 92 .

This article was added to the list of excellent articles on September 27, 2020 in this version .

[NED-1] NGC 224. In: NASA / IPAC EXTRAGALACTIC DATABASE. August 22, 2007, accessed September 28, 2019 .

[SEDS-2] SEDS : NGC 224

[3] Gerard de Vaucouleurs, Antoinette de Vaucouleurs , Herold G. Corwin, Jr., Ronald J. Buta, Georges Paturel, Pascal Fouque: Third Reference Catalog of Bright Galaxies . Springer, New York, NY (USA) 1991, ISBN 0-387-97552-7 , pp. 2091 , bibcode : 1991rc3..book ..... D ( u-strasbg.fr ).