Andromeda XVIII

DSS image of Andromeda XVIII

Observation data (J2000 epoch)
Constellation| Andromeda
Right ascension|  00h 02m 14.5s[1]
Declination| +45° 05′ 20″[1]
Helio radial velocity| −337.2 km/s[2]
Distance| 4,420 ± 290 kly (1,355 ± 88 kpc)
Group or cluster| Local Group
Apparent magnitude (V)| 15.50 ± 0.24[3]
Absolute magnitude (V)| −10.41 ± 0.28[3]
Characteristics
Type| dSph[1]
Mass| 4.2×106 ± 0.3×106[3] M☉
Half-light radius (physical)| 325 ± 24[4]
Other designations
PGC 5056918[5]

Andromeda XVIII, discovered in 2008, is a dwarf spheroidal galaxy (has no rings, low luminosity, much dark matter, little gas or dust), which is a satellite of the Andromeda Galaxy (M31). It is one of the 14 known dwarf galaxies orbiting M31. It is relatively isolated, being about 1.8 million light-years (579 kpc) away. However, for an isolated dwarf galaxy it is also unusually quiescent. This suggests that Andromeda XVIII is a backsplash galaxy, a galaxy that once had a close orbital encounter with a more massive galaxy which stripped it of much of its star-forming matter. However, alternative hypotheses are also possible for Andromeda XVIII.[2]

## See also

* List of Andromeda's satellite galaxies

## References

1. ↑ 1.0 1.1 1.2 McConnachie, Alan W; Huxor, Avon; Martin, Nicolas F; Irwin, Mike J; Chapman, Scott C; Fahlman, Gregory; Ferguson, Annette M. N; Ibata, Rodrigo A et al. (2008). "A Trio of New Local Group Galaxies with Extreme Properties". The Astrophysical Journal 688 (2): 1009. doi:10.1086/591313. Bibcode: 2008ApJ...688.1009M.
2. ↑ 2.0 2.1 Kvasova, Kateryna A.; Kirby, Evan N.; Beaton, Rachael L. (2024). "Kinematics and Metallicity of the Dwarf Spheroidal Galaxy Andromeda XVIII". The Astrophysical Journal 972 (2): 180. doi:10.3847/1538-4357/ad55f0. Bibcode: 2024ApJ...972..180K.
3. ↑ 3.0 3.1 3.2 Makarova, L. N; Makarov, D. I; Karachentsev, I. D; Tully, R. B; Rizzi, L (2017). "Star formation history of And XVIII: a dwarf spheroidal galaxy in isolation". Monthly Notices of the Royal Astronomical Society 464 (2): 2281. doi:10.1093/mnras/stw2502. Bibcode: 2017MNRAS.464.2281M.
4. ↑ Collins, Michelle L. M; Chapman, Scott C; Rich, R. Michael; Ibata, Rodrigo A; Martin, Nicolas F; Irwin, Michael J; Bate, Nicholas F; Lewis, Geraint F et al. (2013). "A Kinematic Study of the Andromeda Dwarf Spheroidal System". The Astrophysical Journal 768 (2): 172. doi:10.1088/0004-637X/768/2/172. Bibcode: 2013ApJ...768..172C.
5. ↑ "NAME Andromeda XVIII". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NAME+Andromeda+XVIII.

* v
* t
* e

Andromeda Galaxy

Location|

Andromeda Galaxy → Andromeda subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Observable universe → Universe
Each  → may be read as "within" or "part of".

Andromeda Galaxy

Satellite galaxies|

* M32
* M110
* NGC 185
* NGC 147
* Andromeda I
* Andromeda II
* Andromeda III
* Andromeda IV*
* Andromeda V
* Andromeda VI
* Andromeda VII
* Andromeda VIII
* Andromeda IX
* Andromeda X
* Andromeda XI
* Andromeda XII
* Andromeda XIII
* Andromeda XIV
* Andromeda XV
* Andromeda XVI
* Andromeda XVII
* Andromeda XVIII
* Andromeda XIX
* Andromeda XX
* Andromeda XXI
* Andromeda XXII
* Andromeda XXIII
* Andromeda XXIV
* Andromeda XXV
* Andromeda XXVI
* Andromeda XXVII
* Andromeda XXVIII
* Andromeda XXIX
* Triangulum Galaxy*

*It is uncertain whether it is a companion galaxy of the Andromeda Galaxy

Catalogued stars|

* AE Andromedae
* M31-RV

Other|

* Andromeda–Milky Way collision
* S Andromedae
* Mayall II
* M32p
* NGC 206
* 3XMM J004232.1+411314

* Category

* v
* t
* e

Constellation of Andromeda

* Adhil
* Andromeda in Chinese astronomy
* List of Andromeda's satellite galaxies
* List of stars in Andromeda

Stars|

| Bayer|

* α
* β
* γ
* δ
* ε
* ζ
* η
* θ
* ι
* κ
* λ
* μ
* ν
* ξ
* ο
* π
* ρ
* σ
* τ
* υ
* φ
* χ
* ψ
* ω

|

Flamsteed|

* 2
* 3
* 4
* 5
* 6
* 7
* 8
* 9
* 10
* 11
* 12
* 13
* 14
* 15
* 18
* 22
* 23
* 26
* 28
* 32
* 36
* 39
* 41
* 44
* 45
* 47
* 49
* 51
* 55
* 56
* 58
* 59
* 60
* 62
* 63
* 64
* 65
* 66

Variable|

* R
* T
* U
* W
* Z
* RT
* RU
* RV
* RX
* SU
* SW
* TU
* TW
* WZ
* XZ
* AB
* AC
* AD
* AE
* AR
* BM
* BX
* CC
* CN
* DS
* DX
* EG
* ET
* EU
* FF
* GP
* GR
* GY
* HN
* KK
* KX
* KZ
* LL
* LP
* LQ
* OP
* OS
* OU
* PX
* QR
* QV
* QX
* V385
* V455
* V529

HD|

* 3
* 166
* 895
* 1185
* 1606
* 2421
* 2767
* 2942
* 3322
* 3346
* 4778
* 5608
* 5789/5788
* 6114
* 7853
* 8673
* 10307
* 13931
* 14622
* 15082
* 16004
* 16028
* 16175
* 217811
* 220105
* 221246
* 221776
* 222109
* 222399
* 223229
* 224365
* 224801
* 225218

Other|

* 3XMM J004232.1+411314
* 6 Persei
* ADS 48
* Groombridge 34
* HAT-P-6
* HR 178
* HR 8768
* M31-RV
* NGC 44
* NGC 82
* NGC 84
* NGC 91
* NGC 162
* NGC 464
* PA-99-N2
* Ross 248
* WASP-1
* WISE 0146+4234
* WISE J0005+3737
* WISE J004945.61+215120.0

| Exoplanets|

* 14 Andromedae b
* Upsilon Andromedae b
* c
* d
* e
* Gliese 15 Ab
* HD 13931 b
* HD 16175 b
* HAT-P-6b
* HAT-P-32b
* WASP-1b
* WASP-33b

|

| Star clusters|

* Mayall II
* NGC 206
* NGC 272
* NGC 752
* NGC 956
* NGC 7686

|

| Nebulae|

* NGC 7662

|

Galaxies|

| NGC|

* 5
* 11
* 13
* 19
* 21
* 20
* 27
* 39
* 43
* 48
* 49
* 51
* 67
* 68
* 69
* 70
* 71
* 72
* 74
* 76
* 79
* 80
* 81
* 83
* 85
* 86
* 90
* 93
* 94
* 96
* 97
* 108
* 109
* 112
* 140
* 149
* 160
* 169
* 181
* 183
* 184
* 214
* 218
* 226
* 228
* 229
* 233
* 243
* 252
* 258
* 260
* 262
* 280
* 304
* 317
* 389
* 393
* 404
* 425
* 431
* 477
* 478
* 512
* 513
* 523
* 528
* 536
* 668
* 679
* 687
* 700
* 703
* 704
* 705
* 708
* 709
* 710
* 712
* 714
* 717
* 732
* 753
* 759
* 891
* 1000
* 7640
* 7836

|

Numbered|

* I
* II
* III
* IV
* V
* VIII
* IX
* X
* XI
* XVIII
* XIX
* XXI

Other|

* 3C 66A
* 3C 66B
* Andromeda Galaxy
* Donatiello I
* Messier 32
* Messier 110

| Galaxy clusters|

* Abell 262
* NGC 68 group

|

| Astronomical events|

* GRB 101225A
* SN 1885A

|

Category

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