List of Andromeda's satellite galaxies explained
The Andromeda Galaxy (M31) has satellite galaxies just like the Milky Way. Orbiting M31 are at least 13 dwarf galaxies: the brightest and largest is M110, which can be seen with a basic telescope. The second-brightest and closest one to M31 is M32. The other galaxies are fainter, and were mostly discovered starting from the 1970s.
On January 11, 2006, it was announced that Andromeda Galaxy's faint companion galaxies lie on or close to a single plane running through the Andromeda Galaxy's center. This unexpected distribution is not obviously understood in the context of current models for galaxy formation. The plane of satellite galaxies points toward a nearby group of galaxies (M81 Group), possibly tracing the large-scale distribution of dark matter.
It is unknown whether the Triangulum Galaxy is a satellite of Andromeda.
Table of known satellites
Andromeda Galaxy's satellites are listed here by discovery (orbital distance is not known). Andromeda IV is not included in the list, as it was discovered to be roughly 10 times further than Andromeda from the Milky Way in 2014, and therefore a completely unrelated galaxy.
Andromeda Galaxy's satellites| Name | Type | Distance from Sun
(million ly) | Right Ascension** | Declination** | Absolute Magnitude[1] | Apparent magnitude | Mass-to-light ratio | 3D distance to M31 (kly) | Year
discovered | Notes |
|---|
| dE2 | 2.48 | | | | +8.1 | | | 1749 | |
| M110 | dE6 | 2.69 | | | −16.5 | +8.5 | | | 1773 | |
| NGC 185 | dE5 | 2.01 | | | | +10.1 | | | 1787 | |
| NGC 147 | dE5 | 2.2 | | | | +10.5 | | | 1829 | |
| Andromeda I | dSph | 2.43 | | | −11.8 | +13.6 | 31 ± 6 | | 1970 | |
| Andromeda II | dSph | 2.13 | | | −12.6 | +13.5 | 13 ± 3 | | 1970 | |
| Andromeda III | dSph | 2.44 | | | −10.2 | +15.0 | 19 ± 12 | | 1970 | | - | Andromeda IV * | | 22-24 | | | | +16.6 | | | 1972 | Previously believed to be a satellite of Andromeda, but disproven in 2014--> |
| Andromeda V | dSph | 2.52 | | | −9.6 | +15.9 | 78 ± 50[2] | | 1998 | |
Pegasus Dwarf Spheroidal
(Andromeda VI) | dSph | 2.55 | | | −11.5 | +14.2 | 12 ± 5 | | 1998 | |
Cassiopeia Dwarf
(Andromeda VII) | dSph | 2.49 | | | −13.3 | +12.9 | 7.1 ± 2.8 | | 1998 | |
| Andromeda VIII | dSph | 2.7 | | | | +9.1 | | | 2003 | Tidally disrupting; identification unclear |
| dSph | 2.5 | | | −8.3 | +16.2 | | 127.2 | 2004 | |
| Andromeda X | dSph | 2.9 | | | −8.1 | +16.1 | 63 ± 40 | 332.7 | 2005 | |
| Andromeda XI[3] | dSph | | | | −7.3 | | | | 2006 | |
| Andromeda XII | dSph | | | | −6.4 | | | | 2006 | |
| Andromeda XIII (Pisces III) | dSph | | | | −6.9 | | | | 2006 | |
| Andromeda XIV[4] (Pisces IV) | dSph | | | | −8.3 | | 102 ± 71 | | 2007 | |
| Andromeda XV | dSph | | | | −9.4 | | | | 2007 | |
| Andromeda XVI (Pisces V) | dSph | 2.143[5] | | | −9.2 | | | 580.6 | 2007 | |
| Andromeda XVII | dSph | | | | −8.5 | | | 313.1 | 2008 | |
| Andromeda XVIII | dSph/Sm | | | | | | | 515.3 | 2008 | |
| Andromeda XIX | dSph | | | | −9.3 | | | | 2008 | |
| Andromeda XX | dSph | | | | −6.3 | | | 512.1 | 2008 | |
| Andromeda XXI | dSph | | | | −9.9 | | | 472.9 | 2009 | |
| Andromeda XXII | dSph | | | | −7.0 | | | 910 | 2009 | |
| Andromeda XXIII | dIrr | | | | | | | 427.3 | 2011 | |
| Andromeda XXIV | | | | | | | | 401.2 | 2011 | |
| Andromeda XXV | | | | | | | | 319.6 | 2011 | |
| Andromeda XXVI | | | | | | | | 489.2 | 2011 | |
| Andromeda XXVII | | | | | | | | | 2011 | Tidally disrupted[6] |
| Andromeda XXVIII[7] | dSph | | | | | | | | 2011 | |
| Andromeda XXIX | dIrr | | | | | | | 636 | 2011 | |
| Andromeda XXX (Cassiopeia II)[8] | dSph? | | | | | | | | | |
| Andromeda XXXI (Lacerta I) | dSph? | | | | | | | | 2013 | |
| Andromeda XXXII (Cassiopeia III) | dSph? | | | | | | | | 2013 | |
| Andromeda XXXIII (Perseus I) | dSph? | | | | | | | | 2013 | |
Tidal Stream Northwest
(Tidal Stream E and F)[9] | | | | | | | | | 2009 | |
| Tidal Stream Southwest | | | | | | | | | 2009 | |
| Pegasus V galaxy (Peg V) | d | 682kpc | ±0.1 | ±3 | −6.3 | | | 245kpc | 2022 | [10] [11] [12] |
| Triangulum Galaxy
| SA(s)cd | 2.59 | | | | +6.27 | | | 1654? | It is around 750000 light years from Andromeda.[13] Its relation to Andromeda is uncertain. |
|
- RA/DEC values marked in Italics are rough estimates.
- Martin et al. (2009) gave aliases to several satellite galaxies of the Andromeda Galaxy that are located in Pisces.[14] However, the name Pisces II was later used for a different galaxy that is a satellite of the Milky Way,[15] so it is not used here.
See also
External links
Notes and References
- 2010ApJ...711..671K . The SPLASH Survey: Internal Kinematics, Chemical Abundances, and Masses of the Andromeda I, II, III, VII, X, and XIV Dwarf Spheroidal Galaxies . Kalirai . Jason S. . Beaton . Rachael L. . Geha . Marla C.. Marla Geha . Gilbert . Karoline M. . Guhathakurta . Puragra . Kirby . Evan N. . Majewski . Steven R. . Ostheimer . James C. . Patterson . Richard J. . Wolf . Joe . The Astrophysical Journal . 2010 . 711 . 2 . 671–692 . 10.1088/0004-637X/711/2/671 . 0911.1998 . 43188686 .
- 2011MNRAS.417.1170C . The scatter about the 'Universal' dwarf spheroidal mass profile: A kinematic study of the M31 satellites and V and VI . Collins . M. L. M. . Chapman . S. C. . Rich . R. M. . Irwin . M. J. . Peñarrubia . J. . Ibata . R. A. . Arimoto . N. . Brooks . A. M. . Ferguson . A. M. N. . Lewis . G. F. . McConnachie . A. W. . Venn . K. . Monthly Notices of the Royal Astronomical Society . 2011 . 417 . 2 . 1170 . 10.1111/j.1365-2966.2011.19342.x . free . 1103.2121 . 6345715 .
- astro-ph/0607472 . 10.1111/j.1365-2966.2006.10823.x . Discovery and analysis of three faint dwarf galaxies and a globular cluster in the outer halo of the Andromeda galaxy . 2006 . Martin . N. F. . Ibata . R. A. . Irwin . M. J. . Chapman . S. . Lewis . G. F. . Ferguson . A. M. N. . Tanvir . N. . McConnachie . A. W. . Monthly Notices of the Royal Astronomical Society . 371 . 4 . 1983–1991 . free . 2006MNRAS.371.1983M . 20171599 .
- http://spider.seds.org/spider/LG/Add/lg_dis.html Discovery of the Local Group Galaxies
- 10.3847/0004-637X/819/2/147 . The Islands Project. I. Andromeda Xvi, an Extremely Low Mass Galaxy Not Quenched by Reionization . 2016 . Monelli . Matteo . Martínez-Vázquez . Clara E. . Bernard . Edouard J. . Gallart . Carme . Skillman . Evan D. . Weisz . Daniel R. . Dolphin . Andrew E. . Hidalgo . Sebastian L. . Cole . Andrew A. . Martin . Nicolas F. . Aparicio . Antonio . Cassisi . Santi . Boylan-Kolchin . Michael . Mayer . Lucio . McConnachie . Alan . McQuinn . Kristen B. W. . Navarro . Julio F. . The Astrophysical Journal . 819 . 2 . 147 . 1603.00625 . 2016ApJ...819..147M . 32263075 . free .
- 10.1093/mnras/stz2529. 1909.09661. 2019MNRAS.490.2905P. A dwarf disrupting - Andromeda XXVII and the North West Stream. Preston, Janet. Collins, Michelle L. M.. Ibata, Rodrigo A.. Tollerud, Erik J.. Rich, R. Michael. Bonaca, Ana. McConnachie, Alan W.. Mackey, Dougal. Lewis, Geraint F.. Martin, Nicolas F.. Peñarrubia, Jorge. Chapman, Scott C.. Delorme, Maxime. Monthly Notices of the Royal Astronomical Society. 2019 . 490. 2. 2905–2917. free .
- (reprinted in R&D Magazine)
- McConnachie . Alan W. . 2012 . The observed properties of dwarf galaxies in and around the Local Group . The Astronomical Journal . 144 . 1 . 4 . 1204.1562 . 10.1088/0004-6256/144/1/4. 2012AJ....144....4M . 118515618 .
- http://www.ucolick.org/~raja/aas_prs_rls_010610/ New tidal streams found in Andromeda reveal history of galactic mergers
- News: Pegasus V: New Ultra-Faint Dwarf Galaxy Spotted in Outskirts of Andromeda . 1 July 2022 . Sci-News .
- News: New fossil galaxy discovery could answer important questions about the history of the universe . 30 June 2022 . University of Surrey . EurkAlert! . AAAS .
- 2204.09068 . Collins . Michelle L. M. . Charles . Emily J. E. . Martínez-Delgado . David . Monelli . Matteo . Karim . Noushin . Donatiello . Giuseppe . Tollerud . Erik J. . Boschin . Walter . Pegasus V/Andromeda XXXIV–a newly discovered ultrafaint dwarf galaxy on the outskirts of Andromeda . Monthly Notices of the Royal Astronomical Society: Letters . 2022 . 515 . 1 . L72–L77 . 10.1093/mnrasl/slac063 . free . 2022MNRAS.515L..72C .
- Web site: Messier Object 33. 2021-05-21. www.messier.seds.org.
- Martin. Nicolas F.. McConnachie, Alan W.. Irwin, Mike. Widrow, Lawrence M.. Ferguson, Annette M. N.. Ibata, Rodrigo A.. Dubinski, John. Babul, Arif. Chapman, Scott. Fardal, Mark. Lewis, Geraint F.. Navarro, Julio. Rich, R. Michael. 8. PAndAS' CUBS: Discovery of Two New Dwarf Galaxies in the Surroundings of the Andromeda and Triangulum Galaxies. The Astrophysical Journal. 1 November 2009. 705. 1. 758–765 . 10.1088/0004-637X/705/1/758 . 0909.0399 . 2009ApJ...705..758M . 15277245.
- Belokurov. V.. Walker. M. G.. Evans. N. W.. Gilmore. G.. Gerard F. Gilmore. Irwin. M. J.. Just. D.. Koposov. S.. Mateo. M.. Olszewski. E.. Watkins. L.. Wyrzykowski. L.. Big Fish, Little Fish: Two New Ultra-Faint Satellites of the Milky Way. 10.1088/2041-8205/712/1/L103. The Astrophysical Journal. 712. L103–L106. 2010. 1 . 1002.0504. 2010ApJ...712L.103B. 29195107 .
