Andromeda Galaxy

Andromeda Galaxy
A visible light image of the Andromeda Galaxy and two satellite galaxies. Messier 32 is above the galactic nucleus and Messier 110 is at the bottom.
Observation data (J2000 epoch)
Pronunciation/ænˈdrɒmɪdə/
ConstellationAndromeda
Right ascension00h 42m 44.3s[1]
Declination+41° 16′ 9″[1]
Redshiftz = −0.001004 (minus sign indicates blueshift)[1]
Heliocentric radial velocity−301 ± 1 km/s[2]
Distance765 kpc (2.50 Mly)[3]
Apparent magnitude (V)3.44[4][5]
Absolute magnitude (V)−21.5[a][6]
Characteristics
TypeSA(s)b[1]
Mass(1.5±0.2)×1012[7] M☉
Number of stars~1 trillion (1012)[10]
Size152,000 ly
(46.56 kpc)
(diameter; D25 isophote)[1][8][b]
Apparent size (V)3.167° × 1°[1]
H I scale length (physical)≥100 kpc
(326,000 ly)[11]
Other designations
M31, NGC 224, UGC 454, PGC 2557, 2C 56 (Core),[1] CGCG 535-17, 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 is a barred spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a D25 isophotal diameter of about 46.56 kiloparsecs (152,000 light-years)[8] and is approximately 765 kpc (2.5 million light-years) from Earth. The galaxy's name stems from the area of Earth's sky in which it appears, the constellation of Andromeda, which itself is named after the princess who was the wife of Perseus in Greek mythology.[8]

The virial mass of the Andromeda Galaxy is of the same order of magnitude as that of the Milky Way, at 1 trillion solar masses (2.0×1042 kilograms). The mass of either galaxy is difficult to estimate with any accuracy, but it was long thought that the Andromeda Galaxy was more massive than the Milky Way by a margin of some 25% to 50%.[12] However, this has been called into question by early-21st-century studies indicating a possibly lower mass for the Andromeda Galaxy[12] and a higher mass for the Milky Way.[13][14] The Andromeda Galaxy has a diameter of about 46.56 kpc (152,000 ly), making it the largest member of the Local Group of galaxies in terms of extension.[14]

The Milky Way and Andromeda galaxies have about a 50% chance of colliding with each other in the next 10 billion years,[15] merging to potentially form a giant elliptical galaxy[16] or a large lenticular galaxy.[17]

With an apparent magnitude of 3.4, the Andromeda Galaxy is among the brightest of the Messier objects,[18] and is visible to the naked eye from Earth on moonless nights,[19] even when viewed from areas with moderate light pollution.[8]

  1. ^ a b c d e f g Cite error: The named reference ned was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference Karachentsevetal2006 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference adam was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference SIMBAD-M31 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference GAXEL was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Ribas2005 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference GalaxyMass was invoked but never defined (see the help page).
  8. ^ a b c d De Vaucouleurs, Gerard; De Vaucouleurs, Antoinette; Corwin, Herold G.; Buta, Ronald J.; Paturel, Georges; Fouque, Pascal (1991). Third Reference Catalogue of Bright Galaxies. Bibcode:1991rc3..book.....D.
  9. ^ Cite error: The named reference Chapman et al 2006 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference trillion-stars was invoked but never defined (see the help page).
  11. ^ Thilker, David A.; Braun, Robert; Walterbos, Ren A. M.; Corbelli, Edvige; Lockman, Felix J.; Murphy, Edward; Maddalena, Ronald (2004). "On the Continuing Formation of the Andromeda Galaxy: Detection of H i Clouds in the M31 Halo". The Astrophysical Journal. 601 (1): L39 – L42. arXiv:astro-ph/0311571. Bibcode:2004ApJ...601L..39T. doi:10.1086/381703.
  12. ^ a b Cite error: The named reference Kafle2018 was invoked but never defined (see the help page).
  13. ^ López-Corredoira, M.; Prieto, C. Allende; Garzón, F.; Wang, H.; Liu, C.; Deng, L. (1 April 2018). "Disk stars in the Milky Way detected beyond 25 kpc from its center". Astronomy & Astrophysics. 612: L8. arXiv:1804.03064. Bibcode:2018A&A...612L...8L. doi:10.1051/0004-6361/201832880 – via aanda.org.
  14. ^ a b Cite error: The named reference As-Now was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference :2 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference milky-way-collide was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Ueda2014 was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference Frommert & Kronberg 2007 was invoked but never defined (see the help page).
  19. ^ Cite error: The named reference Messie was invoked but never defined (see the help page).


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