Messier 87

Messier 87 (M87 for short, also known as NGC 4486 ) is an 8.6 mag bright elliptical giant galaxy with an area of 8.3 '× 6.6' in the constellation Virgo . M87 is a very active galaxy as radio source as Virgo A , as X-ray source as Virgo X-1 is referred to. The galaxy, about 55 million light-years away, is located near the center of the Virgo Galaxy Cluster , of which it is the largest member, although it is surpassed in brightness in the visual range of the spectrum of M49 . The mass of M87 is approximately 2 to 3 trillion solar masses within a radius of 100,000 light years (32 kpc ) .

It was confirmed on April 10, 2019 that in the center of this galaxy there is a supermassive black hole with a mass of 6.5 billion solar masses. This black hole is the center of the active galaxies core (engl. Active galactic nucleus - AGN) of M87, from which a light is at least 5000 years of high-energy jet is ejected, which can be observed in different wavelengths.

Halton Arp organized his catalog of unusual galaxies into groups according to purely morphological criteria. This galaxy belongs to the class galaxies with jets (149–152) (Arp catalog).

M87 has the largest known system of globular clusters in a galaxy. While the Milky Way has around 200 globular clusters, M87 is assumed to have 12,000 such objects. Since M87 is the largest elliptical giant galaxy in the Virgo supercluster and represents one of the strongest radio sources in the sky, this galaxy is both a popular observation object for amateur astronomy and of outstanding importance as an astronomical research object.

Discovery and history of research

In March 1781, the French astronomer Charles Messier , after having discovered the elliptical galaxy Messier 49 ten years earlier , entered further bright member galaxies of the Virgo galaxy cluster that he and his friend Pierre Méchain had discovered in his catalog , including the nebula messier 87.

A century later, in the 1880s, the Danish-American astronomer John Dreyer entered this nebula in his New General Catalog under the number NGC 4486. This collection was based on the General Catalog of Nebulae and Clusters by John Herschel published in the 1860s .

In 1918, the American astronomer Heber Curtis of the Lick Observatory described that M87 did not show any spiral structure, but noted at the same time that a "strange straight beam ... apparently connected to the core by a thin material line", the inner one End becomes lighter. At that time, the existence of extragalactic objects was still unknown and galaxies were therefore only categorized as nebulae , so that the nature of the jet discovered by Curtis could not yet be classified. In the following year, a supernova exploded in M87, which was only discovered on photo plates by I. Balanowski in 1922 and was initially classified as a possible nova. Its maximum brightness, measured on February 24, 1919, was 11.5 ^m . A month later the brightness had dropped to 12.4 ^m , the following year it was photographed for the last time and was only about 20 ^m bright. To date (2011) this is the only supernova that has been observed in M87.

M87 has historically played a prominent role in the study of the structure of elliptical galaxies. The American astronomer Edwin Hubble , who became known for his discovery of the extragalactic nature of the spiral nebula, initially classified M87 as a lighter globular cluster , since M87 does not have a spiral structure, but nevertheless appeared to be non-galactic in nature. In 1926 he proposed the categorization of these extragalactic nebulae, which is now named after him, and classified M87 as an elliptical extragalactic nebula without noticeable flattening ( Hubble type E0). In 1931, Hubble gave an initial value for the distance of M87 and the other nebulae in the Virgo Cluster. With a value of 1.8 Mpc (about 5.9 million light years), however, it was, as with all galaxies, far below today's value. At that time, M87 was the only elliptical nebula in which single stars could be detected. The term extragalactic nebula stayed that way for some time, but from 1956 M87 is called the E0 galaxy.

In 1947, a powerful radio source was discovered in the direction of M87, which was named Virgo A. The link between the source and the galaxy was revealed in 1953, and the jet emerging from the core of the galaxy was suggested as a possible source of the radiation. In 1969–1970, it was found that a large proportion of the radiation is actually closely related to the optical source of the jet.

The United States Naval Research Laboratory launched an Aerobee 150 rocket in April 1965 to investigate possible astronomical X-ray sources. Seven possible sources have been found, including Virgo X-1 as the first extragalactic source. Another Aerobee missile, launched from the White Sands Missile Range in July 1967 , condensed evidence that the X-ray source Virgo X-1 is related to the M87 galaxy. Investigations by the High Energy Astronomy Observatory 1 and the Einstein Observatory then showed that the source has a complex structure that is related to the AGN of M87. However, the radiation hardly shows any compression towards the center.

properties

In the extended classification scheme for galaxies of de Vaucouleurs M87 is called E0p. E0 describes an elliptical energy without significant deviations from the spherical shape. The letter p stands for pekuliar (special, peculiar) and indicates the existing characteristics that do not fit into the scheme, such as the jet. Partly, but not uniformly, M87 is also referred to as the cD galaxy , i. H. as a supergiant galaxy with an extensive diffuse but dust-free halo in the center of a galaxy cluster.

The distance between the galaxy was determined using various independent methods. Examples are luminance measurements planetary nebula (engl. Planetary nebula luminosity function - PNLF), the distribution functions of the radii and luminosities of the globular clusters (engl. Globular cluster luminosity function , surface brightness fluctuations -GCLF) (engl. Surface brightness function - SBF) and the T RGB -Method ( tip of the red giant branch ) that uses the tip of the red giant branch of the individually resolved red giants of the galaxy. The more recent measurements provide consistent values within the scope of the measurement accuracy for the distance of an average of 54 million light years (16.7 Mpc), with a standard deviation of the measurements of about 6 million light years (1.8 Mpc). The distance module results from this at 31.1 ^m , which results in an absolute brightness of the galaxy of −23.5 ^m .

Trapped mass
Measures in 10 ¹² M _☉	Radius in kpc
2.4	32
3.0	44
6.0	50

The mass density of the galaxy falls steadily from the center outwards. Newer models show that the course of the density function can be approximated as a power law in certain areas. These models show that the density is roughly proportional to r ^−α , where r is the distance from the center and α is a parameter that indicates the strength of the decrease in the density function. Depending on the observation method, α = 1.3 (dynamics of the globular clusters in the halo within r <40 kpc) to α = 1.7 (analysis of the X-rays for 50 kpc < r <100 kpc). The mass of the galaxy then increases roughly proportionally to r ^1.7 within the range of 9–40 kpc . Newer models with α = 1.2 result in a mass of (2.4 ± 0.6) × 10 ¹² solar masses within 32 kpc , which corresponds to about twice the mass of the Milky Way . Other observations, also with the help of globular clusters or X-ray observations, also allow mass determinations up to a greater distance, as shown in the adjacent table. As with all galaxies, only part of the mass is in stars, which is expressed by the mass-luminosity ratio of 6.3 ± 0.8; d. That is, only about a sixth of the mass is in self-luminous stars. The total mass of M87 could be 200 times the mass of the Milky Way.

The vast, star-populated shell of the galaxy extends up to a distance of about 160 kpc (for comparison: the extent of the Milky Way in this sense is about 100 kpc). Beyond this limit, the edge of this galaxy appears to be cut off. The mechanism that led to this could be a close encounter with another galaxy at a cosmologically earlier point in time. There are indications of a linear star stream moving in the galaxy's northwest direction and which could have been formed by the tidal action of orbiting neighboring galaxies or the collision of small satellite galaxies with M87.

construction

core

Representation calculated from Event Horizon Telescope images, which possibly shows the surroundings of the supermassive black hole M87 * in the center of Messier 87. The black area in the center of the image is approximately 2.5 times the diameter of the event horizon .

In the center of the active galaxy core of M87 there is a supermassive black hole ( English supermassive black hole - SMBH) with the designation M87 * (unofficially also called "Pōwehi"). Its mass is estimated to be (6.6 ± 0.4) × 10 ⁹ solar masses. It is one of the most massive black holes known. It is also the first black hole whose “ shadow ” has ever been observed. The Schwarzschild radius of this black hole is then about 20 billion km and is therefore much larger than the semi-axis of the orbit of Pluto and all other known (dwarf) planets. The black hole is surrounded by a rotating accretion disk of ionized gas, which should be perpendicular to the giant jet emerging from the core of the galaxy. The gas in the disk moves at speeds of up to around 1000 km / s. and is eventually accreted by the black hole . The accretion rate is estimated to be around 0.1 solar masses per year. Measurements of the position of the black hole showed that it is not located directly in the geometric center of M87, but is shifted by about 25 light years in relation to it. This shift is opposite in direction to the direction of the jet, indicating that the black hole was set in motion by the jet relative to the core of the galaxy. Another explanation is that the shift was caused by the merging of two black holes in the center of the galaxy. More recent results even suggest that the shift is only an optical effect that may have been caused by a flare of the jet. Measurements from 2011 did not detect a statistically significant shift.

The core of M87 is also the source of strong gamma radiation . This radiation was first observed in the later 1990s. In 2006 , changes in the flow of gamma rays from M87 were detected using the High Energy Stereoscopic System , a so-called Cherenkov telescope. These variations take place within a few days, so that the source must be very small. A connection with the environment of the black hole is therefore obvious.

Various calculated images, which with a certain probability represent the "shadow" of the black hole in the center of M 87 and the surrounding accretion flows, were presented in April 2019 by the collaboration of the Event Horizon Telescope (see there). They were created two years earlier, but the scientists needed two years to analyze the data and validate their observations. The dark area in the center of the picture, which is surrounded by luminous areas, is the so-called shadow of the black hole. The black hole shows good agreement with simulations based on general relativity. From the data, the mass could be estimated at around 6.5 billion solar masses and also statements about the rotation of the black hole, but no precise statements about the angular momentum.

jet

Detail of the M87 jet

Comparison of an optical image from the Hubble space telescope (top right) with an image from a radio telescope

This image from the Chandra X-ray telescope shows the matter falling from the Virgo Cluster into the center of M87, where it hits the jet, creating a shock wave in the galaxy's interstellar medium.

The jet of M87, discovered in 1918, arises from the active galaxy core and extends from there at least 5000 light years. The direction of this jet corresponds to a position angle of 260 °, i.e. i.e., it runs roughly in a westerly direction (slightly south). The apparent length of the jet is about 20 arc seconds with a width of about 2 arc seconds. The jet consists of matter that is accelerated in the accretion disk of the black hole in the center. The matter flows out approximately perpendicular to the accretion disk in the form of a strongly collimated beam, which then moves close to the core up to about 6 light years (2 pc) away at a spatial angle of about 16 ° diameter, at a distance of up to 40 light years (12 pc) is limited to a diameter of 6-7 °. There is evidence of a jet going in the opposite direction. These cannot be checked optically, however, since so-called relativistic beaming , a relativistic effect of the propagation of light, greatly reduces this counter jet in its apparent brightness.

The German astronomer Walter Baade found in 1956 that the light from the jet is linearly polarized . This suggests that the jet's energy is generated by the acceleration of electrons to relativistic speeds in a magnetic field . The optical light emission of the jet is excited by the fastest electrons, the energy of which is around 100 to 1000 GeV . The total energy of the electrons in the jet is estimated to be about 5 × 10 ⁴⁹ joules .

Scraps of matter from the jet could be detected up to a distance of 250,000 light years. With recordings from the Hubble Space Telescope from 1999, the flow speed of the matter in the jet of M87 was determined and this measurement resulted in a purely geometric analysis, a speed that corresponds to four to five times the speed of light . Apparent superluminal velocities of this kind are known from other jets and are an optical effect of the special theory of relativity, which occurs when flows in the direction of the observer at a velocity close to but below the speed of light. The analysis of this movement proves the theory that quasars , BL Lacertae objects and radio galaxies all arise from the same astrophysical mechanism of active galaxy nuclei and only look different due to different observation situations.

Observations with the Chandra X-ray telescope suggest arcs and rings in the hot X-ray emitting gas that penetrates and surrounds the galaxy. These structures should be created by pressure waves created by changes in the rate of mass ejection from the accretion disk into the jet. The distribution of the loops suggests that smaller eruptions occur about six million years apart. One of the rings, created by a major eruption, represents a shock wave 85,000 light years in diameter around the central black hole. Other notable details are filaments that are up to 100,000 light years long and emit radiation in a narrow range of X-rays, as well a large recess in the hot gas that was created by a major eruption 70,000 years ago. The regular eruptions prevent the surrounding gas from cooling down, thus preventing the star formation process in this region. This mechanism could have had a major impact on the evolution of the galaxy.

The Hubble Space Telescope and Chandra X-ray Telescope both observed a node in the jet that is about 210 light years (65 pc) from the core. In a period of about four years up to 2006, the X-ray intensity of this nodule had increased by a factor of 50 and has been decreasing at a variable rate since then.

Star population and interstellar medium

The elliptical shape of the galaxy is due to the statistical disordered distribution of the orbital planes of the member stars of the galaxy, in contrast to spiral galaxies, in which the orbital planes largely have a similar direction (parallel to the disk ). It is generally believed that active giant elliptical galaxies such as M87 arise from mergers of smaller galaxies. The galaxy, which looks essentially structurelessly diffuse, shows small structures like optical filaments that make up an estimated mass of 10,000 solar masses.

As it stands, there is little dust left in M87's interstellar medium to form diffuse nebulae from which new stars can emerge. The star population is therefore predominantly old and is dominated by Population II stars , which contain few so-called metals (i.e. elements heavier than helium in an astrophysical context).

The interstellar space in M87, however, is filled with gas chemically enriched with heavier elements that was ejected from stars at the end of their lifespan after the main sequence phase . Carbon and nitrogen are constantly being given off by medium-weight stars located in the giant asymptotic branch . Heavier elements from oxygen to iron are mainly formed by supernovae . About 60% of the abundance of these heavier elements is thought to be formed by core collapse supernovae , while the remainder is primarily derived from type Ia supernovae . The distribution of these elements suggests that in earlier times this enrichment was primarily due to core collapse supernovae. The proportion from this source was, however, much lower than is the case with the Milky Way. Type Ia supernovae likely made a significant contribution to the entire history of M87.

Far infrared analyzes show exceptionally high emissions at wavelengths above 25 μm. Usually such emission is indicative of thermal radiation given off by relatively cold dust. In the absence of large amounts of dust, however, the emissions from M87 seem to have their origin in synchrotron radiation from the jet. The low dust content can be explained by the strong X-rays from the core of the galaxy. Models show that silicate grains cannot survive longer than about 46 million years due to the X-rays inside the galaxy. The dust may be destroyed or driven out of the galaxy. It is believed that the total mass of dust in M87 is no more than 70,000 solar masses. For comparison, the mass of dust in the Milky Way is about 100 million (10 ⁸ ) solar masses.

Within a radius of 4 kpc around the core of the galaxy is what is known as metallicity , i. H. the abundance of elements other than hydrogen and helium, about half that in the sun . The metallicity increases steadily at a greater distance from the core. The entire galaxy is surrounded by an extensive corona of hot, low-density gas.

Globular clusters

M87 has an unusually large number of globular clusters. A 2006 survey conducted up to an angular distance of 25 arc minutes from the core found an estimated number of 12,000 ± 800 clusters in orbit around M87. The Milky Way, for example, has only 150-200 such clusters. The globular clusters of M87 have a similar distribution in terms of their diameter and their luminosity as the globular clusters of the Milky Way. Most piles are between 1 and 6 kpc in radius. Due to the significantly higher number, it is statistically not unexpected that the largest of the globular clusters of M87 are significantly larger than the largest globular cluster in the Milky Way, Omega Centauri . The brightest globular clusters have apparent brightnesses of 21.3 ^m on the B-band, corresponding to an absolute magnitude of -9.8 ^M . This is pretty much the absolute magnitude of Mayall II , the brightest globular cluster in the Local Group, and about 0.8 mag brighter than Omega Centauri. However, individual globular clusters of M87 are significantly brighter and have brightnesses of up to 19 ^m and therefore clearly surpass all globular clusters of the local group with an absolute brightness of about −12 ^M.

The distance determination with the help of the brightness of globular clusters already described above is no longer carried out by comparing the absolutely brightest clusters, but with the globular cluster luminosity function (GCLF). Here the distribution of the frequencies of the brightnesses and in particular the turnover , i. H. the maximum of the distribution function, used for comparison. The absolute turnover of the GCLF of the Milky Way is −7.4 ^M (V-band), for M87 the V-band appears to be 23.7 ^m , resulting in a distance module of 31.1 ^m , corresponding to a distance of 16.6 Mpc.

A total of over 700 large globular clusters with a brightness over 22.5 ^m (absolute −8.6 ^M ) in the B-band were counted. The size of the globular clusters of M87 shows a gradual increase with increasing distance from the core of the galaxy.

Membership in the Virgo Bunch

M87 (bottom left) in the Virgo cluster. The two large neighboring galaxies M84 and M86 can be seen at the top right. By fading out the foreground stars, the diffuse light between the cluster members can be seen.

The supergiant galaxy M87 is located in the center of the Virgo galaxy cluster . This relatively large galaxy cluster has about 200 large and about 2000 smaller member galaxies . The Virgo cluster forms the center of the Virgo supercluster , which also includes the Local Group and thus the Milky Way . The cluster can be divided into three larger subgroups, which are grouped around the giant galaxies M87, M49 and M60 . The group around M87 is the most massive and M87 forms the gravitational center. This is also expressed by the low peculiar velocity of this galaxy, i.e. H. it moves very little with respect to the other cluster members. Hence, M87 is defined as the center of the Virgo cluster. The total mass of the cluster is estimated to be (0.15–1.5) × 10 ¹⁵ solar masses.

The subgroup around M87 also includes the elliptical galaxies M84 and M86 . Measurements of the movements of planetary nebulae located within the cluster between M87 and M86 indicate that the two galaxies are moving towards each other. It could be their first close encounter. M87 has likely had a close encounter with M84 in the past. This is indicated by the clipped outer halo of M87, which may have been lost due to tidal effects during the encounter. But there are also alternative explanations for this phenomenon, which are associated with dark matter or an interaction with the active galaxy core.

Observability

The location of M87 in the constellation Virgo

M87 is not far from the northern border of the constellation Virgo and the constellation Haar der Berenike . The galaxy is located near the imaginary line that connects the stars Vindemiatrix (ε Vir) and Denebola (β Leo). With an apparent brightness of 8.6 ^m with an angular extent of 8.3 '× 6.6' (the bright central area measures around 45 "), the galaxy can already be observed with better binoculars and small telescopes with an opening from 6 cm. At an aperture of 120 mm, M87 appears with a diameter of 3 arc minutes, at 350 mm with a diameter of 5 arc minutes.

Visual observation of the jet is considered a challenge for amateur astronomers. Before the 1990s, the only visual observation report of the jet came from Otto von Struve , who observed it using the Hooker telescope with an aperture of 2.5 meters. The jet can be successfully observed with large amateur telescopes under excellent conditions, this requires an aperture of at least 400 mm.

Trivia

M87 formed the background for volumes 300 to 399 of the Perry Rhodan science fiction series .

Web links

Commons : Messier 87 - album with pictures, videos and audio files

literature

Jeff Kanipe and Dennis Webb: The Arp Atlas of Peculiar Galaxies - A Chronicle and Observer's Guide , Richmond 2006, ISBN 978-0-943396-76-7

Individual evidence

↑ ^a ^b ^c ^d ^e NASA / IPAC EXTRAGALACTIC DATABASE
↑ ^a ^b ^c ^d ^e SEDS : NGC 4486
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↑ Joss Bland-Hawthorn, Ken Freeman: The Baryon Halo of the Milky Way: A Fossil Record of Its Formation . In: Science . 287, No. 5450, Jan. 7, 2000, pp. 79-84. bibcode : 2000Sci ... 287 ... 79B . doi : 10.1126 / science.287.5450.79 . PMID 10615053 .

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↑ ^a ^b Kazunori Akiyama u. a. (Event Horizon Telescope Collaboration): First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole, Astroph. J. Letters, April 10, 2019, IOPScience

↑ Donna Lu: How do you name a black hole? It is actually pretty complicated . In: New Scientist . April 19, 2019. "For the case of M87 *, which is the designation of this black hole, a (very nice) name has been proposed, but it has not received an official IAU approval"

↑ Black Hole Cam. Accessed April 10, 2019 .

↑ ^a ^b Karl Gebhardt, et al .: The Black-Hole Mass in M87 from Gemini / NIFS Adaptive Optics Observations . In: The Astrophysical Journal . (accepted), 2011. arxiv : 1101.1954 . bibcode : 2011ApJ ... 729..119G . doi : 10.1088 / 0004-637X / 729/2/119 .

↑ F. Macchetto, A. Marconi,, DJ Axon , A. Capetti, W. Sparks, P. Crane: The Supermassive Black Hole of M87 and the Kinematics of Its Associated Gaseous Disk . In: Astrophysical Journal . 489, No. 2, November 1997, p. 579. arxiv : astro-ph / 9706252 . bibcode : 1997ApJ ... 489..579M . doi : 10.1086 / 304823 .

^ Tiziana Di Matteo, Steven W. Allen, Andrew C. Fabian, Andrew S. Wilson, Andrew J. Young: Accretion onto the Supermassive Black Hole in M87 . In: The Astrophysical Journal . 582, No. 1, January 2003, pp. 133-140. arxiv : astro-ph / 0202238 . bibcode : 2003ApJ ... 582..133D . doi : 10.1086 / 344504 .

^ ^A ^b D. Batcheldor, A. Robinson, DJ Axon, ES Perlman, D. Merritt: A Displaced Supermassive Black Hole in M87 . In: The Astrophysical Journal Letters . 717, No. 1, July 2010, pp. L6-L10. arxiv : 1005.2173 . bibcode : 2010ApJ ... 717L ... 6B . doi : 10.1088 / 2041-8205 / 717/1 / L6 .

↑ Ron Cowen: Black hole shoved aside, along with 'central' dogma . In: ScienceNews . 177, No. 13, June 19, 2010, p. 9. Retrieved May 29, 2010.

↑ Bernd Wirsing: Discovery of Gamma Rays from the Edge of a Black Hole , Max Planck Society. October 26, 2006. Retrieved December 3, 2010.

↑ YY Kovalev, ML Lister, DC Homan, KI Kellermann: The Inner Jet of the Radio Galaxy M87 . In: The Astrophysical Journal . 668, No. 1, October 2007, pp. L27-L30. bibcode : 2007ApJ ... 668L..27K . doi : 10.1086 / 522603 .

^ William B. Sparks, D. Fraix-Burnet, F. Macchetto, FN Owen: A counterjet in the elliptical galaxy M87 . In: Nature . 355, No. 6363, February 27, 1992, pp. 804-806. bibcode : 1992Natur.355..804S . doi : 10.1038 / 355804a0 .

^ JE Baldwin, FG Smith: Radio emission from the extragalactic nebula M87 . In: The Observatory . 76, August 1956, pp. 141-144. bibcode : 1956Obs .... 76..141B .

↑ U. Klein: The Large-Scale Structure of Virgo A . In: Hermann-Josef Röser, Klaus Meisenheimer (Eds.): The radio galaxy Messier 87, Lecture notes in physics . tape 530 . Springer, 1997, doi : 10.1007 / BFb0106418 (September 15-19 , 1997, Ringberg Castle, Tegernsee (Germany)).

↑ JA Biretta, WB Sparks, F. Macchetto: Hubble Space Telescope Observations of Superluminal Motion in the M87 Jet . In: The Astrophysical Journal . 520, No. 2, August 1999, pp. 621-626. bibcode : 1999ApJ ... 520..621B . doi : 10.1086 / 307499 .

↑ John Biretta: Hubble detects faster-than-light motion in Galaxy M87 . Space Telescope Science Institute. January 6, 1999. Retrieved December 8, 2010.

↑ Steve Roy, Watzke, Megan: Chandra Reviews Black Hole Musical: Epic But Off-Key . In: Chandra . Harvard-Smithsonian Center for Astrophysics. October 2006. Retrieved April 25, 2010.

^ DE Harris, CC Cheung, JA Biretta, WB Sparks ,; W. Junor, ES Perlman, AS Wilson: The Outburst of HST-1 in the M87 Jet . In: The Astrophysical Journal . 640, No. 1, March 2006, pp. 211-218. arxiv : astro-ph / 0511755 . bibcode : 2006ApJ ... 640..211H . doi : 10.1086 / 500081 .

^ DE Harris, CC Cheung, L. Stawarz: Variability Timescales in the M87 Jet: Signatures of E Squared Losses, Discovery of a Quasi-period in HST-1, and the Site of TeV Flaring . In: Bulletin of the American Astronomical Society . 41, January 2009, p. 393. arxiv : 0904.3925 . bibcode : 2009AAS ... 21333207H .

↑ Wolfgang Steinicke, Richard Jakiel: Galaxies and how to observe them. In: Astronomers' observing guides. Springer, 2007, ISBN 1-85233-752-4 , pp. 32-33.

↑ Walter Dehnen: M 87 as a Galaxy . In: Hermann-Josef Röser, Klaus Meisenheimer (Ed.): The radio galaxy Messier 87: proceedings of a workshop . Springer, 1997, p. 31 , doi : 10.1007 / BFb0106415 (September 15-19 , 1997, Ringberg Castle, Tegernsee (Germany)).

^ JO Burns, RA White, MP Haynes: A search for neutral hydrogen in D and cD galaxies . In: Astronomical Journal . 86, August 1981, pp. 1120-1125. bibcode : 1981AJ ..... 86.1120B . doi : 10.1086 / 112992 .

↑ N. Werner, H. Böhringer, JS Kaastra, J. de Plaa, A. Simionescu, J. Vink: XMM-Newton high-resolution spectroscopy reveals the chemical evolution of M 87 . In: Astronomy and Astrophysics . 459, No. 2, November 2006, pp. 353-360. arxiv : astro-ph / 0608177 . bibcode : 2006A & A ... 459..353W . doi : 10.1051 / 0004-6361: 20065678 .

↑ ^a ^b M. S. Clemens et al .: The Herschel Virgo Cluster Survey. III. A constraint on dust grain lifetime in early-type galaxies . In: Astronomy and Astrophysics . 518, July 2010. bibcode : 2010A & A ... 518L..50C . doi : 10.1051 / 0004-6361 / 201014533 .

↑ M. Baes et al .: The Herschel Virgo Cluster Survey. VI. The far-infrared view of M 87 . In: Astronomy and Astrophysics . 518, July 2010. bibcode : 2010A & A ... 518L..53B . doi : 10.1051 / 0004-6361 / 201014555 .

^ Mark H. Jones, Robert J. Lambourne, David John Adams: An introduction to galaxies and cosmology. Cambridge University Press, 2004, ISBN 0-521-54623-0 , p. 13.

^ ^A ^b William E. Harris, Gretchen LH Harris, Dean E. McLaughlin: M87, Globular Clusters, and Galactic Winds: Issues in Giant Galaxy Formation . In: The Astronomical Journal . 115, No. 5, May 1998, pp. 1801-1822. arxiv : astro-ph / 9801214 . bibcode : 1998AJ .... 115.1801H . doi : 10.1086 / 300322 . The authors state the following metallicity within a radius of 3 kpc:

{\ displaystyle {\ begin {smallmatrix} \ left [{\ frac {Fe} {H}} \ right] \ = \ -0.3 \ end {smallmatrix}}}

^ SE Strom et al .: The halo globular clusters of the giant elliptical galaxy Messier 87 . In: Astrophysical Journal . tape 245 , no. 1 , April 1981, pp. 416-452 , doi : 10.1086 / 158820 .

↑ ^a ^b A. Sandage: A New Determination of the Hubble Constant from Globular Clusters in M87 . In: Astrophysical Journal . tape 152 , June 1968, p. L149 , doi : 10.1086 / 180201 .

↑ ^a ^b Bradley C. Whitmore et al .: Hubble Space Telescope Observations of Globular Clusters in M87 and an Estimate of H 0 . In: Astrophysical Journal Letters . tape 454 , December 1995, p. L73 , doi : 10.1086 / 309788 .

^ A. Sandage, GA Tammann: An Alternate Calculation of the Distance to M87 Using the Whitmore et al. Luminosity Function for Its Globular Clusters: H0 Therefrom . In: Astrophysical Journal . tape 464 , June 1996, p. L51-L54 , doi : 10.1086 / 310083 .

↑ JG Cohen, A. Ryzhov: The Dynamics of the M87 globular cluster system . In: Astrophysical Journal . tape 486 , no. 1 , September 1997, p. 230 , doi : 10.1086 / 304518 .

↑ Juan P. Madrid, William E. Harris, John P. Blakeslee, Matías Gómez: Structural Parameters of the Messier 87 Globular . In: The Astrophysical Journal . 705, No. 1, November 2009, pp. 237-244. bibcode : 2009ApJ ... 705..237M . doi : 10.1088 / 0004-637X / 705/1/237 . See Figure 6. for a plot of the effective cluster radius versus galactocentric distance.

↑ ^a ^b Patrick Côté, et al .: The ACS Virgo Cluster Survey. I. Introduction to the Survey . In: The Astrophysical Journal Supplement Series . 153, No. 1, July 2004, pp. 223-242. arxiv : astro-ph / 0404138 . bibcode : 2004ApJS..153..223C . doi : 10.1086 / 421490 .

↑ Vindemiatrix is at the coordinates α = 13 ^h 02 ^m , δ = + 10 ° 57 ′ 0 ″ ; Denebola is at α = 11 ^h 49 ^m , δ = + 14 ° 34 ′ 0 ″ . The center (arithmetically) is at α = 12 ^h 16 ^m , δ = + 12 ° 45 ′ 0 ″ . Comparison with M87: α = 12 ^h 31 ^m , δ = + 12 ° 23 ′ 0 ″ .1302002105700114900214340012160021245001231002122300

↑ Christian B. Luginbuhl, Brian A. Skiff: Observing Handbook and Catalog of Deep Sky Objects , 2nd edition, Cambridge University Press, 1998, ISBN 0-521-62556-4 , S. 266th

↑ Ronald Stoyan , Stefan Binnewies, Susanne Friedrich: Atlas of the Messier objects . 2006, ISBN 978-3-938469-07-1 , pp. 368 . See p. 294

^ Antony Cooke: Visual astronomy under dark skies. A new approach to observing deep space. In: Patrick Moore's practical astronomy series. Springer-Verlag, London 2005, ISBN 1-85233-901-2 , pp. 5-37.

^ Roger Nelson Clark: Visual astronomy of the deep sky . CUP Archive, 1990, ISBN 0-521-36155-9 , p. 153.

↑ Visual observations of the M87 jet . In: Adventures in Deep Space . Astronomy Mall. Retrieved December 7, 2010.

↑ 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. 164

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[apj640_1-55] DE Harris, CC Cheung, JA Biretta, WB Sparks ,; W. Junor, ES Perlman, AS Wilson: The Outburst of HST-1 in the M87 Jet . In: The Astrophysical Journal . 640, No. 1, March 2006, pp. 211-218. arxiv : astro-ph / 0511755 . bibcode : 2006ApJ ... 640..211H . doi : 10.1086 / 500081 .

[baas41-56] DE Harris, CC Cheung, L. Stawarz: Variability Timescales in the M87 Jet: Signatures of E Squared Losses, Discovery of a Quasi-period in HST-1, and the Site of TeV Flaring . In: Bulletin of the American Astronomical Society . 41, January 2009, p. 393. arxiv : 0904.3925 . bibcode : 2009AAS ... 21333207H .

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[aj86-59] JO Burns, RA White, MP Haynes: A search for neutral hydrogen in D and cD galaxies . In: Astronomical Journal . 86, August 1981, pp. 1120-1125. bibcode : 1981AJ ..... 86.1120B . doi : 10.1086 / 112992 .

[aaa459_2-60] N. Werner, H. Böhringer, JS Kaastra, J. de Plaa, A. Simionescu, J. Vink: XMM-Newton high-resolution spectroscopy reveals the chemical evolution of M 87 . In: Astronomy and Astrophysics . 459, No. 2, November 2006, pp. 353-360. arxiv : astro-ph / 0608177 . bibcode : 2006A & A ... 459..353W . doi : 10.1051 / 0004-6361: 20065678 .

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[aaa518_2-62] M. Baes et al .: The Herschel Virgo Cluster Survey. VI. The far-infrared view of M 87 . In: Astronomy and Astrophysics . 518, July 2010. bibcode : 2010A & A ... 518L..53B . doi : 10.1051 / 0004-6361 / 201014555 .

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[aj115_5-64] A ^b William E. Harris, Gretchen LH Harris, Dean E. McLaughlin: M87, Globular Clusters, and Galactic Winds: Issues in Giant Galaxy Formation . In: The Astronomical Journal . 115, No. 5, May 1998, pp. 1801-1822. arxiv : astro-ph / 9801214 . bibcode : 1998AJ .... 115.1801H . doi : 10.1086 / 300322 . The authors state the following metallicity within a radius of 3 kpc:
${\ displaystyle {\ begin {smallmatrix} \ left [{\ frac {Fe} {H}} \ right] \ = \ -0.3 \ end {smallmatrix}}}$

[strom81-65] SE Strom et al .: The halo globular clusters of the giant elliptical galaxy Messier 87 . In: Astrophysical Journal . tape 245 , no. 1 , April 1981, pp. 416-452 , doi : 10.1086 / 158820 .

[sandage68-66] A. Sandage: A New Determination of the Hubble Constant from Globular Clusters in M87 . In: Astrophysical Journal . tape 152 , June 1968, p. L149 , doi : 10.1086 / 180201 .

[whitmore95-67] Bradley C. Whitmore et al .: Hubble Space Telescope Observations of Globular Clusters in M87 and an Estimate of H 0 . In: Astrophysical Journal Letters . tape 454 , December 1995, p. L73 , doi : 10.1086 / 309788 .

[santam96-68] A. Sandage, GA Tammann: An Alternate Calculation of the Distance to M87 Using the Whitmore et al. Luminosity Function for Its Globular Clusters: H0 Therefrom . In: Astrophysical Journal . tape 464 , June 1996, p. L51-L54 , doi : 10.1086 / 310083 .

[cohen97-69] JG Cohen, A. Ryzhov: The Dynamics of the M87 globular cluster system . In: Astrophysical Journal . tape 486 , no. 1 , September 1997, p. 230 , doi : 10.1086 / 304518 .

[apj705_1_237-70] Juan P. Madrid, William E. Harris, John P. Blakeslee, Matías Gómez: Structural Parameters of the Messier 87 Globular . In: The Astrophysical Journal . 705, No. 1, November 2009, pp. 237-244. bibcode : 2009ApJ ... 705..237M . doi : 10.1088 / 0004-637X / 705/1/237 . See Figure 6. for a plot of the effective cluster radius versus galactocentric distance.

[apjss153_1_223-71] Patrick Côté, et al .: The ACS Virgo Cluster Survey. I. Introduction to the Survey . In: The Astrophysical Journal Supplement Series . 153, No. 1, July 2004, pp. 223-242. arxiv : astro-ph / 0404138 . bibcode : 2004ApJS..153..223C . doi : 10.1086 / 421490 .

[midway-72] Vindemiatrix is at the coordinates α = 13 ^h 02 ^m , δ = + 10 ° 57 ′ 0 ″ ; Denebola is at α = 11 ^h 49 ^m , δ = + 14 ° 34 ′ 0 ″ . The center (arithmetically) is at α = 12 ^h 16 ^m , δ = + 12 ° 45 ′ 0 ″ . Comparison with M87: α = 12 ^h 31 ^m , δ = + 12 ° 23 ′ 0 ″ .1302002105700114900214340012160021245001231002122300

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[stoyan-74] Ronald Stoyan , Stefan Binnewies, Susanne Friedrich: Atlas of the Messier objects . 2006, ISBN 978-3-938469-07-1 , pp. 368 . See p. 294

[cooke2005-75] Antony Cooke: Visual astronomy under dark skies. A new approach to observing deep space. In: Patrick Moore's practical astronomy series. Springer-Verlag, London 2005, ISBN 1-85233-901-2 , pp. 5-37.

[clark90-76] Roger Nelson Clark: Visual astronomy of the deep sky . CUP Archive, 1990, ISBN 0-521-36155-9 , p. 153.

[astromall-77] Visual observations of the M87 jet . In: Adventures in Deep Space . Astronomy Mall. Retrieved December 7, 2010.

[Messier-Objekte-78] 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. 164