Maffei 1

It was named after the astronomer Paolo Maffei named, who in the year 1967 together with its neighboring galaxy Maffei 2 by means of their emission of infrared radiation discovered.

Maffei 1 has a slightly flattened nucleus, a box-like shape, and consists mainly of old metal-rich stars . However, stars are still forming in the inner, small, blue core of the galaxy . Like all elliptical galaxies, Maffei 1 has a significant number of globular clusters . It is located in a distance of about three to four mega parsecs (about 9.8 to 13.1 million light-years) of our Milky Way . It is therefore probably the closest giant galaxy to us.

Maffei 1 is located in the galactic plane of the Milky Way in the so-called Zone of Avoidance , known for obscuring the background with a high number of stars and interstellar dust . If we had a clear view of Maffei 1 , it would probably be the largest, with about three-quarters the diameter of the moon, the brightest and most famous galaxy in the night sky. In the optical range it can be observed in a very dark sky with telescopes from an opening of about 30 centimeters .

discovery

The Italian astronomer Paolo Maffei was one of the pioneers of infrared astronomy . In the 50s and 60s of the 20th century , he used chemically hypersensitized Eastman emulsions IN to obtain high quality images of celestial objects in the near-infrared part of the spectrum (I-band 680-880 nm). In order to achieve this hypersensitization, he immersed her in a 5% ammonia solution for 3 to 5 minutes . This approach increased their sensitivity by an order of magnitude. Between 1957 and 1967 Maffei observed many different celestial objects using this technique, such as B. Globular clusters and planetary nebulae . Some of these objects were not visible at all on recordings in blue light (B-band 250-500 nm).

The galaxy Maffei 1 was then discovered on a hypersensitized IN photo plate, which was taken on September 29, 1967 with a Schmidt telescope at the Osservatorio Astrofisico di Asiago . Paolo Maffei found Maffei 1 together with its direct neighboring spiral galaxy Maffei 2, while he was actually searching the images for diffuse nebulae and T-Tauri stars . The object had an apparent size of 50 arcseconds on the near-infrared image, but was not visible at all on a corresponding image in the blue.

However, the spectrum had neither emission nor absorption lines . Later it could also be shown that she showed almost no activity in the radio area either. In 1970 , Hyron Spinrad was the first to suspect that Maffei 1 was a heavily shielded giant elliptical galaxy close to us.

Maffei 1 would fall among the 10 brightest galaxies in the northern night sky if it were not covered by our Milky Way galaxy.

Due to the weakness of light in optical recordings, you need at least a telescope with an aperture of 30 to 35 centimeters, high-quality, exact star maps and a very dark night sky for visual observation of Maffei 1 .

distance

Maffei 1 is only 0.55 ° away from the galactic plane and is therefore in the middle of the so-called Zone of Avoidance . It is therefore subject to an extinction of 4.7 magnitudes (a factor of about 1/70) in the visual. In addition, there is the disturbance from myriads of weak foreground stars of the Milky Way, which can easily be confused with the stars of Maffei 1 . This makes a precise determination of the distance particularly difficult.

In 1971 , soon after their discovery, Hyron Spinrad estimated the distance to be around 1 Mpc, which would have placed them within the local group. In 1983, Ronald Buta and Marshall McCall had to correct this estimate to (2.1 ± ) Mpc. They used the general relationship between brightness and velocity dispersion within elliptical galaxies. Maffei 1 clearly placed this distance outside of our local group, but still close enough to have influenced it in the past. ${\ displaystyle _ {0.8} ^ {1.3}}$

In 1993 Gerard Luppino and John Tonry used the surface brightness fluctuations to get new estimates of (4.15 ± 0.5) Mpc. In 2001 , Tim Davidge and Sidney van den Bergh were able to use adaptive optics to resolve the brightest single stars of the asymptotic giant branch in Maffei 1 and thus derive a distance of (4.4 ± ) Mpc. The current determination of the distance is based on a recalibrated brightness-velocity dispersion relationship for elliptical galaxies and updated absorbance and comes to (2.85 ± 0.36) Mpc. If all the measurement results are summarized, the average distance is (3.32 ± 0.72) Mpc. ${\ displaystyle _ {0.5} ^ {0.6}}$

The greater distances greater than 3 Mpc, which have been derived over the last 20 years, also mean that Maffei 1 was never close enough to significantly influence the dynamics of the local group.

Maffei 1 is moving away from our solar system at a speed of about 66 km / s. The escape speed in relation to the center of gravity of the local group amounts to 297 km / s, a speed corresponding to the distance-dependent value of the expansion of the universe of this galaxy.

properties

Size and shape

The surface brightness profile of Maffei 1 in the blue B-band and in the near-infrared I-band

Maffei 1 is the blue elliptical galaxy in the lower right corner, Maffei 2 is the spiral galaxy in the upper left.

Maffei 1 is a giant elliptical galaxy, classified as Type E3 in the Hubble sequence . That means the galaxy is slightly flattened, the small semiaxis is 70% of the length of the major semiaxis. Maffei 1 also has a slight box shape (type E (b) 3), while the central region (radius of about 34 pc) appears somewhat weaker in relation to the r ^1/4 law, which makes Maffei 1 an elliptical core-type galaxy. Both the box shape and the under-luminous core of the galaxy are typical of medium to large elliptical galaxies.

Due to the strong extinction by the Milky Way, the apparent expansion of Maffei 1 depends heavily on the wavelength of the light. In blue light it only has an apparent diameter of one to two arc minutes, while in the near infrared the major axis reaches at least 23 arc minutes, which is roughly three quarters of the diameter of the moon . At a distance of 3 Mpc, this corresponds to an absolute value of approximately 23 kpc. The absolute visual luminosity of M _V = −20.8 ^m corresponds roughly to that of the Milky Way.

core

Maffei 1 has a small, blue, inner nucleus with a diameter of about 1.2 pc. This contains approximately 29 M _{☉ of} ionized hydrogen gas . This implies a very recent star formation phase. However, there are no signs of an active galactic core in the center of Maffei 1 . The X-ray radiation from the nucleus is extensive and likely comes from several stellar sources.

Stars and star clusters

Maffei 1 consists mainly of ancient metal-rich stars more than 10 billion years old. As a large elliptical galaxy, Maffei 1 most likely has a large number of globular clusters (estimated around 1100), but due to the strong extinction, not a single one could be detected with earth-based telescopes.

With the Hubble Space Telescope , 20 candidates for globular clusters around the central region could be identified in 2000 . Subsequent infrared observations from ground-based telescopes also found a population of bright globular cluster candidates.

Group membership

Maffei 1 is one of the dominant members of a galaxy group close to us. The other determining group members are large spiral galaxies such as IC 342 and Maffei 2 . Maffei 1 itself also has a number of satellite galaxies such as the smaller spiral galaxy Dwingeloo 1 and a larger number of other dwarf galaxies such as MB 1 . The Maffei group is one of the galaxy groups closest to our Milky Way. Maffei 1 and its satellites form a subgroup of the Maffei group, the Maffei 1 subgroup.

gallery

The heart and soul mists . The small blue ellipse below the heart nebula on the edge of the picture is Maffei 1.
The overall picture with Maffei 1 and Maffei 2.

Web links

Maffei 1
SEDS : Maffei 1
Sky-Map.org
Galaxies Beyond the Heart: Maffei 1 and 2 - Astronomy Picture of the Day 2010 March 9

Remarks

^ "Eastman Emulsions IN" refers to a type of photographic plate manufactured in the 20th century by Eastman Kodak . They were sensitive in the very near part of the infrared spectrum and were widely used for astronomical observation at the time. Nevertheless, long exposure times were necessary and were therefore often hypersensitized.

↑ The r ^1/4 law refers to an empirical observation that relates the surface brightness to the radius, the distance to the center of elliptical galaxies. The following is shown: with r radius μ surface brightness (in mag / arsec ² ) while A and B represent empirical constants.
${\ displaystyle \ mu = A + Br ^ {1/4}}$

Individual evidence

↑ ^a ^b ^c ^d ^e NASA / IPAC Extragalactic Database . In: Results for Maffei 1 . Retrieved October 24, 2011.

↑ ^a ^b ^c ^d ^e ^f ^g Fingerhut, RL, McCall, ML; De Robertis, M .; Kingsburgh, RL; Komljenovic, M .; Lee, H .; Buta, RJ: "The Extinction and Distance of Maffei 1" . In: The Astrophysical Journal . 587 (2), 2003, p. 672 .. doi : 10.1086 / 368339 .

↑ ^a ^b ^c ^d Fingerhut, RL, Lee, H .; McCall, ML; Richer, MG: "The Extinction and Distance of Maffei 2 and a New View of the IC 342 / Maffei Group" . In: The Astrophysical Journal . 655 (2), 2007, p. 814. doi : 10.1086 / 509862 .

↑ ^a ^b ^c Davidge, TJ, Van Den Bergh, S .: "The Detection of Bright Asymptotic Giant Branch Stars in the Nearby Elliptical Galaxy Maffei 1" . In: The Astrophysical Journal . 553 (2), 2001, p. L133. doi : 10.1086 / 320692 .

↑ N. Sanduleak: Hypersentivization Gains in the Near Infrared . In: The Astronomical Journal . 66, 1961, pp. 526-8. bibcode : 1961AJ ..... 66..526S . doi : 10.1086 / 108456 .

↑ ^a ^b Paolo Maffei: My researches at the infrared doors . In: Memorie della Società Astronomica Italiana . 74, 2003, pp. 19-28. bibcode : 2003MmSAI..74 ... 19M .

^ Maffei, P .: "Infrared Object in the Region of IC 1895" . In: Publications of the Astronomical Society of the Pacific . 80, 1968, p. 618. bibcode : 1968PASP ... 80..618M . doi : 10.1086 / 128698 .

↑ Bell, MB, Seaquist, ER; Braun, LD: "Nonthermal Radio Emission from an Infrared Object in the Region of IC 1805" . In: The Astrophysical Journal . 161, 1970, p. L13. doi : 10.1086 / 180561 .

↑ Trusock, Tom: Small Wonders: Cassiopeia Archived from the original on November 13, 2011. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (pdf) In: cloudynights.com (Ed.): Cloudy Nights Telescope Reviews . November 6, 2005. Retrieved May 16, 2012. @1@ 2

↑ ^a ^b Karachentsev, ID, Sharina, ME; Dolphin, AE; Grebel, EK: "Distances to nearby galaxies around IC 342" . In: Astronomy and Astrophysics . 408, 2003, p. 111. bibcode : 2003A & A ... 408..111K . doi : 10.1051 / 0004-6361: 20030912 .

^ ^A ^b ^c ^d Buta, RJ, McCall, ML: "The IC 342 / Maffei Group Revealed" . In: The Astrophysical Journal Supplement Series . 124, 1999, p. 33. doi : 10.1086 / 313255 .

^ ^A ^b ^c Buta, R., McCall, ML: "Maffei 1 with the Hubble Space Telescope" . In: The Astronomical Journal . 125 (3), 2003, p. 1150. doi : 10.1086 / 367789 .

^ ^A ^b ^c Davidge, TJ: "The Upper Asymptotic Giant Branch of the Elliptical Galaxy Maffei 1 and Comparisons with M32 and NGC 5128" . In: The Astronomical Journal . 124 (4), 2002, p. 2012. doi : 10.1086 / 342535 .

↑ Davidge, TJ, Van Den Bergh, S .: "The Globular Cluster Content of Maffei 1" . In: Publications of the Astronomical Society of the Pacific . 117 (832), 2005, p. 589. arxiv : astro-ph / 0504335 . bibcode : 2005PASP..117..589D . doi : 10.1086 / 430367 .

[5] "Eastman Emulsions IN" refers to a type of photographic plate manufactured in the 20th century by Eastman Kodak . They were sensitive in the very near part of the infrared spectrum and were widely used for astronomical observation at the time. Nevertheless, long exposure times were necessary and were therefore often hypersensitized.

[ned-1] NASA / IPAC Extragalactic Database . In: Results for Maffei 1 . Retrieved October 24, 2011.

[Fingerhut2003-2] ↑ ^a ^b ^c ^d ^e ^f ^g Fingerhut, RL, McCall, ML; De Robertis, M .; Kingsburgh, RL; Komljenovic, M .; Lee, H .; Buta, RJ: "The Extinction and Distance of Maffei 1" . In: The Astrophysical Journal . 587 (2), 2003, p. 672 .. doi : 10.1086 / 368339 .

[Fingerhut2007-3] Fingerhut, RL, Lee, H .; McCall, ML; Richer, MG: "The Extinction and Distance of Maffei 2 and a New View of the IC 342 / Maffei Group" . In: The Astrophysical Journal . 655 (2), 2007, p. 814. doi : 10.1086 / 509862 .

[Davidge2001-4] Davidge, TJ, Van Den Bergh, S .: "The Detection of Bright Asymptotic Giant Branch Stars in the Nearby Elliptical Galaxy Maffei 1" . In: The Astrophysical Journal . 553 (2), 2001, p. L133. doi : 10.1086 / 320692 .

[Snaduleak1961-6] N. Sanduleak: Hypersentivization Gains in the Near Infrared . In: The Astronomical Journal . 66, 1961, pp. 526-8. bibcode : 1961AJ ..... 66..526S . doi : 10.1086 / 108456 .

[Maffei2003-7] Paolo Maffei: My researches at the infrared doors . In: Memorie della Società Astronomica Italiana . 74, 2003, pp. 19-28. bibcode : 2003MmSAI..74 ... 19M .

[Maffei1968-8] Maffei, P .: "Infrared Object in the Region of IC 1895" . In: Publications of the Astronomical Society of the Pacific . 80, 1968, p. 618. bibcode : 1968PASP ... 80..618M . doi : 10.1086 / 128698 .

[Bell1970-9] Bell, MB, Seaquist, ER; Braun, LD: "Nonthermal Radio Emission from an Infrared Object in the Region of IC 1805" . In: The Astrophysical Journal . 161, 1970, p. L13. doi : 10.1086 / 180561 .