The Local Group of Galaxies (LG) is a small but diverse collection of different types of galaxies: First the three big spirals (S) - our Milky Way (MW), the Andromeda Galaxy M31, and the Triangulum Galaxy M33, itself maybe a satellite of M31. Then there are some elliptical (E) and irregular (I or S[B]m) galaxies, as satellites of the big ones or field members of the Local Group. Furthermore there is the small formation of dwarf galaxies around NGC 3109, which may or may not be members of the LG.
And then there are the little ones: plenty of dwarf spheroidal (dSph) and only recently discovered ultra faint dwarf (UFD) galaxies at the lower size limit toward globular clusters. Not to forget the many less observable features as gaseous and dark matter halos and stellar tidal streams.
With this chart here I tried to show all the discovered galactic members of the Local Group as seen from Earth, with known (or at least suspected) subgroups color-coded (see below). Because of the concentration of satellites around M31 the complete galaxy names are only visible at higher zoom level. Rotate the view with mouse- or fingertip-dragging, zoom with mouse wheel or pinch, depending on what kind of interface you are using. The source for the underlying map can be found at my Github repository.
The equatorial yellow line is the galactic plane and the pink line is the supergalactic plane.
● Milky Way
● M31(Andromeda)
● NGC 3109
◆ Spiral
⬬ Elliptical
▲ Irregular
● Dwarf Spheroidal (dSph)
● Ultra Faint Dwarf (UFD)
In the last decades many discoveries have improved our picture of the Local Group. In particular the Sloan Digital Sky survey (SDSS), the PAndAS survey (Pan-Andromeda Archaeological Survey) and Gaia have enabled many discoveries of very faint objects, while infrared surveys continue to search through the galactic plane to find objects so far hidden behind it. The SDSS has for the most part only probed the northern hemisphere, so there may also lurk many undiscovered dSphs and UFDs in the southern hemisphere.
As the count stands so far, there are 122 members of the Local Group so far and 5 probables. 65 are satellites of the Milky Way, 42 of M31. The census by morphological type: 8 (dwarf)spirals, 5 ellipticals, 18 irregulars, 43 dwarf spheroidals and 53 UFDs. Below is a list with data of all members and candidates:
Name Alt. Name l b M Rh Dh Dnear Metal. Type Subgroup
° ° mag pc kpc kpc [Fe/H]
Milky Way Gal.Cntr. 0 0 -20.9 8.5 460 SABbc I-II MW
Sagittarius I SagDEG 5.57 -14.16 -13.5 1550 26 16.0 -0.5 dSph(t) MW
UKS 2323-326 UGCA 438 11.87 -70.86 -13.1 770 1350 IBm V-VI pec LG??
Sagittarius II Laevens 5 18.9 -22.9 -5.2 32 67 60 -2.28 UFD MW
SagDIG Sagittarius dIrr 21.06 -16.28 -11.5 930 1180 -2.1 IBm V-VI: LG
NGC 6822 DDO 209 25.35 -18.38 -16.0 490 670 -1.2 IBm V-VI LG
Boötes III Boö III 27.39 55.43 -5.8 170 46 44.0 -2.1 UFD MW
Hercules I Her I 28.73 36.87 -6.6 330 132 134.2 -2.41 UFD MW
Aquarius I DDO 210 34.05 -31.34 -10.6 216 565 960 -1.3 IBm V-VI LG
Aquarius II 55.11 -53.01 -4.36 159 108 -2.3 UFD MW
Pegasus III 69.85 -41.81 -3.4 78 215 -2.1 UFD MW
Boötes IV Boö IV 70.682 53.305 -4.53 462 209 -2.2 UFD MW
Canes Venatici ICVn I 74.31 79.82 -8.6 564 218 219.8 -1.98 dSph MW
WLM DDO 221 75.86 -73.62 -14.2 917 1122 810 -1.27 IBm V-VI LG
Pisces II 79.21 -47.11 -5.0 60 182 180 -2.45 UFD MW
Draco I DDO 208 86.37 34.72 -8.8 196 76 82 -1.93 dSph pec MW
Andromeda XXVIII 91.03 -22.93 -8.5 210 650 365 -2.0 dSph M31
PegDIG DDO 216 94.78 -43.55 -12.2 783 410 -1.4 Im V-VI M31?
Draco II Laevens 4 98.3 42.9 -2.9 19 21.5 22 -2.7 UFD MW
Lacerta I Andromeda XXXI 101.1 -16.7 -11.7 912 756 275 dSph M31
Cetus I KKS 1 101.46 -72.85 -11.2 590 755 620 -1.9 dSph LG
Ursa Minor I DDO 199 104.97 44.80 -8.8 280 76.0 68.0 -2.13 dSph MW
Pegasus I Andromeda VI 106.04 -36.32 -11.3 424 919 265 -1.3 dSph M31
Cassiopeia I Andromeda VII 109.46 -9.95 -12.6 740 763 215 -1.4 dSph M31
Andromeda XXIX 109.80 -30.77 -8.3 360 730 207 -1.8 dSph M31
Andromeda XXI 111.9 -19.2 -9.9 842 827 135 -1.8 dSph M31
Andromeda XX 112.9 -26.9 -6.3 114 741 128 -1.5 UFD M31
Canes Venatici IICVn II 113.58 82.70 -4.9 74 160 150.7 -2.21 UFD MW
Andromeda XVIII 113.9 -16.9 -9.7 325 1214 357 -1.8 dSph M31?
Andromeda XIX 115.6 -27.4 -9.2 1481 821 115 -1.9 dSph M31
Andromeda XXVI 118.1 -14.7 -7.1 219 754 103 -1.9 dSph M31
IC 10 118.96 -3.33 -15.0 500 660 255 -1.28 IBm V-VI M31?
Andromeda XXV 119.2 -15.9 -9.7 642 736 90 -1.8 dSph M31
Andromeda III KK 5 119.37 -26.26 -10.2 360 723 86 -1.78 dSph M31
NGC 147 DDO 3 119.82 -14.25 -15.1 503 712 118 -1.1 dE5 M31
Andromeda XVII 120.23 -18.47 -8.7 262 727 67 -1.9 dSph M31
Andromeda XXVII 120.4 -17.4 -7.9 657 1255 482 -1.7 dSph M31
Cassiopeia II Andromeda XXX 120.46 -13.15 -8.0 267 681 145 -1.7 dSph M31
Cassiopeia III Andromeda XXXII 120.5 -11.2 -12.3 1456 772 144 dSph M31
M110 NGC 205 120.72 -21.14 -16.5 673 824 60 -0.8 dE5/p M31
NGC 185 120.79 -14.48 -15.2 266 620 181 -0.8 dE3 M31
Andromeda VIII M31 part 121.02 -22.22 830 - dSph pec: M31
Andromeda IV 121.11 -22.27 -12.6 6300 - dIrr: ??
M32 NGC 221 121.15 -21.98 -16.4 220 770 6 -1.1 cE2 M31
M31 NGC 224 121.17 -21.57 -21.2 4760 785 300 0.42 SAb II M31
Andromeda I KK 8 121.68 -24.82 -11.8 600 727 68 -1.45 dSph/dE3 M31
Andromeda XI 121.72 -29.06 -6.9 158 763 102 -2.0 UFD M31
Andromeda XII 122.00 -28.49 -6.4 324 928 181 -2.1 UFD M31
Andromeda XIV 122.97 -33.17 -8.4 413 793 161 -2.26 dSph M31
Andromeda XIII 123.03 -29.87 -6.7 172 760 115 -1.9 UFD M31
Andromeda IX 123.21 -19.68 -8.1 530 600 182 -2.2 dSph M31
Andromeda XVI 124.91 -30.46 -9.2 170 476 319 -2.1 dSph M31
Andromeda X 125.75 -17.98 -7.6 340 670 130 -1.93 dSph M31
Andromeda V 126.22 -15.12 -9.1 302 742 113 -1.9 dSph M31
LGS 3 Pisces I 126.76 -40.89 -10.1 769 285 -2.1 dIrr/dSph M31?
Andromeda XXIV 127.8 -16.3 -7.6 548 898 169 -1.8 dSph M31
Andromeda XV 127.88 -24.53 -9.4 270 626 174 -1.8 dSph M31
Andromeda II KK 12 128.92 -29.16 -12.4 1230 630 195 -1.64 dSph M31
IC 1613 DDO 8 129.74 -60.58 -15.3 1440 715 505 -1.3 IBm V-VI M31?
Andromeda XXIII 131.0 -23.6 -10.2 1001 748 127 -1.8 dSph M31
Andromeda XXII (Tri I) 132.6 -34.1 -6.5 252 920 275 -1.8 UFD M31
M33 NGC 598 133.61 -31.33 -18.9 3320 820 210 -0.3 SAcd III-IV M31?
UGCA 86 139.76 10.65 -17.7 525 3770 Im V-VI: LG??
Triangulum II Laevens 2 141.4 -23.4 -1.8 16 28.4 36 -2.24 UFD MW
UGCA 92 144.71 10.52 -14.5 640 Im V-VI: LG??
Andromeda XXXIII Perseus I 147.8 -15.5 0,3 400 785 374 dSph M31
Segue II 149.4 -38.1 -2.5 40 37 38.0 -2.22 UFD MW
Ursa Major II UMa II 152.46 37.44 -4.2 140 32 36.5 -2.47 UFD MW
Cetus II 156.48 -78.53 0.0 17 30 -1.28 UFD MW
Willman 1 158.58 56.78 -2.7 25 38 43 -2.1 UFD MW
Ursa Major I UMa I 159.43 54.41 -5.5 318 97 104.9 -2.18 UFD MW
Cetus III 163.81 -61.13 -2.5 90 251 -2.2 UFD MW
UGC 4879 VV 124 164.67 42.88 -12.5 1100 1000 -1.5 IAm LG??
Leo A DDO 69 196.90 52.42 -12.1 475 950 980 -1.4 IBm V-VI LG
Leo T 214.85 43.66 -8.0 178 417 425 -2.02 UFD MW?
Leo P 219.65 54.43 -9.41 290 1750 -1.8 dSph LG?
Leo II DDO 93 220.17 67.23 -9.8 151 233 208 -1.62 dSph pec MW
Segue I 220.5 50.4 -1.5 29 23 25 -2.72 UFD MW
Hydra I Hya I 224.7 29.1 -2.5 12.7 -0.91 UFD MW
Leo I DDO 74 225.99 49.11 -12.0 246 254 254 -1.43 dSph MW
Columba I Col 1 231.62 -28.88 -4.5 103 182 UFD MW
Sextans B DDO 70 233.20 43.78 -14.5 715 1630 730 -1.6 IBm V-VI N310
Fornax I ESO 356-4 237.10 -65.65 -13.4 668 147 140 -0.99 dSph MW
Canis Major I CMa I 239.99 -8.00 -8.3 13.0 8.0 dIrr MW
Coma Berenices I Com I 241.9 83.6 -4.1 77 44 45.2 -2.6 UFD MW
Sextans I 243.50 42.27 -9.27 682 86 89 -1.93 dSph MW
Sextans A DDO 75 246.15 39.88 -14.3 300 1380 530 -1.85 IBm V-VI N310
Eridanus II 249.78 -51.65 -6.6 172 380 -2.38 UFD MW
Pictor I 257.30 -40.65 -3.7 31 126 -1.7 UFD MW
Antlia B Ant B 259.41 21.08 -9.7 273 1290 70 -0.5 dSph N310
Carina I Car 1 260.11 -22.22 -9.1 241 105 103 -1.72 dSph MW
Leo V 261.86 58.54 -5.2 42 178 180.8 -2.0 UFD MW
NGC 3109 DDO 236 262.10 23.07 -15.8 1285 1720 -1.7 SBm V N310
Horologium II 262.47 -54.14 -2.6 47 78 -2.1 UFD MW
Antlia A Ant A 263.10 22.31 -10.7 1320 40 -1.9 IABm V-VI N310
Antlia II Ant II 264.90 11.25 -8.5 2867 129.4 -1.36 dSph MW
Leo IV 265.44 56.51 -5.8 116 154 160.6 -2.54 UFD MW
Reticulum II 266.30 -49.74 -2.7 32 32 -2.46 UFD MW
Pictor II Pic II 269.63 -24.05 -3.2 46 45 -1.8 UFD MW
Carina II Car II 269.98 -17.14 -4.5 91 36.2 -2.44 UFD MW
Carina III Car III 270.01 -16.85 -2.4 30 27.8 -1.80 UFD MW
Horologium I 271.39 -54.73 -3.4 30 79 -2.76 UFD MW
Phenix I ESO 245-7 272.16 -68.95 -9.8 445 445 -1.49 IAm V-VI MW?
Reticulum III 273.88 -45.65 -3.3 64 92 UFD MW
Eridanus III 274.3 -59.60 -2.0 18 87 UFD MW
Virgo I Vir I 276.94 59.58 -0.3 47 91 -2.2 UFD MW
LMC 280.47 -32.89 -18.5 3000 51 50 -0.6 SBm V MW
Crater II Crt II 282.91 42.03 -8.2 1066 118 -1.98 dSph MW
Sculptor I 287.54 -83.16 -10.8 279 86 79 -1.68 dSph MW
Hydra II Hya II 295.61 30.46 -4.8 68 134 128 -2.02 UFD MW
Hydrus I 297.41 -36.74 -4.7 53.3 27.6 -2.52 UFD MW
Centaurus I Cen I 300.26 21.90 -5.6 79 116.3 112.7 -1.8 UFD MW
SMC NGC 292 302.80 -44.30 -16.8 1000 64 57 -1.2 SBm V pec MW
GR 8 DDO 155 310.74 76.98 -12.5 108 940 2500 -2.0 Im V-VI LG??
Tucana IV 313.29 -55.29 -3.5 127 48 -2.49 UFD MW
Tucana III 315.15 -56.19 -2.4 44 25 -2.42 UFD MW
Tucana V 316.31 -51.89 -1.6 17 55 -2.17 UFD MW
Tucana I 322.91 -47.37 -9.6 207 875 1110 -1.58 dE4 LG
Phenix II 323.69 -59.75 -3.7 27 95 UFD MW
Tucana II 328.08 -52.33 -3.8 199 57 -2.23 UFD MW
Grus I 338.68 -58.24 -3.4 70 120 -0.42 UFD MW
IC 5152 ESO 237-27 343.92 -50.19 -15.7 590 1830 -1.4 IAm V-VI LG??
Indus I 347.3 -42.6 -3.5 12 100.0 UFD MW
Grus II 351.15 -51.94 -3.9 93 53 -2.51 UFD MW
Boötes II Boö II 353.7 68.9 -2.7 51 52 47.6 -1.79 UFD MW
Indus II 353.99 -37.40 -4.3 181 214 -2.0 UFD MW
Boötes I Boötes I 358.08 69.62 -6.3 242 66 57.6 -2.55 UFD MW
M: Absolute visual Magnitude, Rh: Half light radius in pc.
Dh: Heliocentric distance in kpc.
Dnear: Distance to the nearest Subgroup center (MW, M31, NGC 3109) in kpc, for those and LG field galaxies
distance to the Local Group barycenter in kpc.
Metal. [Fe/H]: Metallicity = log(NFe/NH)star - log(NFe/NH)sun
Logarithm of the average abundance of elements heavier than helium and hydrogen (= metals), measured as
the spectral ratio of iron to hydrogen relative to the solar ratio.
Subgroup:
There are three such groups currently recognized in the Local Group:
MW: The Milky Way and it's satellite galacies
M31: Andromeda (including M33) and satellites
N3109: The small NGC 3109 group, possible Local Group member
LG are Local Group galaxies not belonging to any subgroup
? means probable, ?? unlikely membership.
Links & References
Old versions of the chart
Milky Way Satellites & The Local Group (SEDS)
Mike Irwin List of Local Group members
PAndAS (The Pan-Andromeda Archaeological Survey)
Metz et al. (2006) The spatial distribution of the Milky Way and Andromeda satellite galaxies arXiv:astro-ph/0610.933v1
Metz et al. (2009) Discs of Satellites: the new dwarf spheroidals arXiv:astro-ph/0901.1658v1
Discovery papers
Milky Way:
Martin et al. (2003) A dwarf galaxy remnant in Canis Major: The fossil of an in-plane accretion onto the Milky Way arXiv:astro-ph/0311.010v1 (CMa dwarf)
Willmann et al. (2005) A New Milky Way Dwarf Galaxy in Ursa Major arXiv:astro-ph/0503.552v2 (UMa I)
Zucker et al. (2006) A New Milky Way Dwarf Satellite in Canes Venatici arXiv:astro-ph/0604.354v1 (CVn I)
Belokurov et al. (2006) Cats and Dogs, Hair and a Hero: A Quintet of New Milky Way Companions arXiv:astro-ph/0608.448v1 (Leo IV, CVn II, Com, Her dSphs & Segue 1)
Zucker et al. (2006) A Curious New Milky Way Satellite in Ursa Major arXiv:astro-ph/0606.633 (UMa II)
Irwin et al. (2007) Discovery of an Unusual Dwarf Galaxy in the Outskirts of the Milky Way arXiv:astro-ph/0701.154v1 (Leo T)
Walsh et al. (2007) A Pair of Boötes - A New Milky Way Satellite arXiv:astro-ph/0705.1378 (Boötes I & II)
Belokurov et al. (2008) Leo V - A Companion of a Companion of the Milky Way Galaxy? arXiv:astro-ph/0807.2831v2 (Leo V)
Belokurov et al. (2010) Big Fish, Small Fish: Two New Ultra-Faint Satellites of the Milky Way. arXiv:astro-ph/1002.0504v1 (Pisces II, Segue 3)
Grillmair, C.J. (2011) Another Look at the EBS: A Stellar Debris Stream and a Possible Progenitor. arXiv:astro-ph/1107.5044v1
Giovanelli et al. (2013) Alfalfa Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo P. arXiv:astro-ph/1305.0272
Sand et al. (2015) Antlia B: A Faint Dwarf Galaxy Member of the NGC 3109 Association. arXiv:astro-ph/1508.01800
Andromeda:
Zucker et al. (2006) Andromeda X, A New Dwarf Spheroidal Satellite of M31: Photometry arXiv:astro-ph/0601.599 (And X)
Martin et al. (2006) Discovery and analysis of three faint dwarf galaxies and a globular cluster in the outer halo of the Andromeda galaxy. arXiv:astro-ph/0607.472v1 (And XI-XIII)
Majewski et al. (2007) Discovery of Andromeda XIV: A Dwarf Spheroidal Dynamical Rogue in the Local Group? arXiv:astro-ph/0702.635v2 (And XIV)
Ibata et al. (2007) The Haunted Halos of Andromeda and Triangulum: A Panorama of Galaxy Formation in Action. (And XV & XVI)
Irwin et al. (2008) Andromeda XVII: A New Low Lumiosity Satellite of M31. arXiv:astro-ph/0802.0698v1 (And XVII)
McConnachie et al. (2008) A trio of new Local Group galaxies with extreme properties. arXiv:astro-ph/0806.3988v1 (And XVIII-XX)
Collins et al. (2009) A Keck/DEIMOS spectroscopic survey of the faint M31 satellites And IX, AndXI, AndXII and AndXIII. arXiv:astro-ph/0911.1365v1
Martin et al. (2009) PAndAs' Cubs: discovery of two new dwarf galaxies in the surroundings of the Andromeda and Triangulum galaxies. arXiv:astro-ph/0909.0399v3 (And XXI+XXII)
Richardson et al. (2010) PAndAs' Progeny: Extending the M31 Dwarf Galaxy Cabal. arXiv:astro-ph/1102.2902v1 (And XXIII-XXVII)
Conn et al. (2012) A Bayesian Approach to Locating the Red Giant Branch Tip Magnitude (Part Ii): Distances to the Satellites of M31. arXiv:astro-ph/1209.4952
Slater et al. (2011) Andromeda XXVIII: A Dwarf Galaxy More Than 350 kpc from Andromeda arXiv:astro-ph/1110.5903
Bell et al. (2011) Andromeda XXIX: A New Dwarf Spheroidal Galaxy 200 kpc from Andromeda arXiv:astro-ph/1110.5906
Conn et al. (2013) The Three-Dimensional Structure of the M31 Satellite System: Strong Evidence for an Inhomogeneous Distribution of Satellites. arXiv:astro-ph/1301.7131
Martin et al. (2013) Lacerta I and Cassiopeia III: Two Luminous and Distant Andromeda Satellite Dwarf Galaxies Found in the 3? Pan-Starrs1 Survey (And XXXI/XXXII) arXiv:astro-ph/1305.5301
