Template:Distinguish Template:Short description Template:Galaxy cluster

The Centaurus A/M83 Group is a complex group of galaxies in the constellations Hydra, Centaurus, and Virgo. The group may be roughly divided into two subgroups. The Cen A Subgroup, at a distance of 11.9 Mly (3.66 Mpc), is centered on Centaurus A, a nearby radio galaxy.<ref name="karachentsev2005">Template:Cite journal</ref> The M83 Subgroup, at a distance of 14.9 Mly (4.56 Mpc), is centered on the Messier 83 (M83), a face-on spiral galaxy.<ref name="karachentsev2005" />

This group is sometimes identified as one group<ref name="nbg">Template:Cite book</ref><ref name="fouqueetal1992">Template:Cite journal</ref> and sometimes identified as two groups.<ref name="garcia1993">Template:Cite journal</ref> Hence, some references will refer to two objects named the Centaurus A Group and the M83 Group. However, the galaxies around Centaurus A and the galaxies around M83 are physically close to each other, and both subgroups appear not to be moving relative to each other.<ref name="karachentsev2005" />

The Centaurus A/M83 Group is part of the Virgo Supercluster, the local supercluster of which the Local Group is an outlying member.

MembersEdit

Member identificationEdit

File:Potw1253a.png
The galaxies NGC 5011B and NGC 5011C are imaged against a starry foreground.<ref>Template:Cite news</ref>

The brightest group members were frequently identified in early galaxy group identification surveys.<ref name="nbg" /><ref name="fouqueetal1992"/> However, many of the dwarf galaxies in the group were only identified in more intensive studies. One of the first of these identified 145 faint objects on optical images from the UK Schmidt Telescope and followed these up in hydrogen line emission with the Parkes Radio Telescope and in the hydrogen-alpha spectral line with the Siding Spring 2.3 m Telescope. This identified 20 dwarf galaxies as members of the group.<ref name="coteetal1997">Template:Cite journal</ref> The HIPASS survey, which was a blind radio survey for hydrogen spectral line emission, found five uncatalogued galaxies in the group and also identified five previously-catalogued galaxies as members.<ref name="banksetal1999">Template:Cite journal</ref> An additional dwarf galaxy was identified as a group member in the HIDEEP survey, which was a more intensive radio survey for hydrogen emission within a smaller region of the sky.<ref name="minchinetal2003">Template:Cite journal</ref> Several optical surveys later identified 20 more candidate objects to the group.<ref name="jerjenetal2000a">Template:Cite journal</ref><ref name="jerjen2002b">Template:Cite journal</ref><ref name="karachentsevetal2002">Template:Cite journal</ref> In 2007, the Cen A group membership of NGC 5011C was established. <ref name="sj2007">Template:Cite journal</ref> While this galaxy is a well-known stellar system listed with a NGC number, its true identity remained hidden because of coordinate confusion and wrong redshifts in the literature. From 2015 to 2017 a full optical survey was conducted using the Dark Energy Camera, covering 550 square degrees in the sky and doubling the number of known dwarf galaxies in this group.<ref>Müller, Oliver, Helmut Jerjen, and Bruno Binggeli. “New Dwarf Galaxy Candidates in the Centaurus Group.” Astronomy & Astrophysics 583 (November 2015): A79. https://doi.org/10.1051/0004-6361/201526748. </ref><ref>Müller, Oliver, Helmut Jerjen, and Bruno Binggeli. “New Low Surface Brightness Dwarf Galaxies in the Centaurus Group.” Astronomy & Astrophysics 597 (January 2017): A7. https://doi.org/10.1051/0004-6361/201628921. </ref> Another deep but spatially limited survey around Centaurus A revealed numerous new dwarfs.<ref>Template:Cite journal</ref>

The dwarf spheroidal galaxies of the Centaurus A group have been studied and have been found to have old, metal-poor stellar populations similar to those in the Local Group, and follow a similar metallicity–luminosity relation. One dwarf galaxy, KK98 203 (LEDA 166167), has an extended ring of Hα emission.<ref>Template:Cite journal</ref>

Member listEdit

The table below lists galaxies that have been identified as associated with the Centaurus A/M83 Group by I. D. Karachentsev and collaborators.<ref name="karachentsev2005" /><ref name="karachentsevetal2002"/> Note that Karachentsev divides this group into two subgroups centered on Centaurus A and Messier 83.

Members of the Centaurus A Subgroup
Name Type<ref name="ned" /> R.A. (J2000)<ref name="ned" /> Dec. (J2000)<ref name="ned" /> Redshift (km/s)<ref name="ned" /> Apparent Magnitude<ref name="ned" />
Cen 7 Sph Template:RA Template:DEC 17.3
Cen N Template:RA Template:DEC 17.5
Centaurus A (NGC 5128) S0 pec Template:RA Template:DEC 547 ± 5 7.8
Centaurus A-dE1 dSph Template:RA Template:DEC 19.3
Centaurus A-dE3 dE Template:RA Template:DEC 17.1
HIPASS J1337-39 Im Template:RA Template:DEC 492 ± 4 16.5
HIPASS J1348-37 Template:RA Template:DEC 581 ± 8 16.9
HIPASS J1351-47 Template:RA Template:DEC 529 ± 6
KKs 51 E/Sph Template:RA Template:DEC 16.7
KKs 55 Sph Template:RA Template:DEC 18.5
KKs 57 Sph Template:RA Template:DEC 18.1
LEDA 166152 dI Template:RA Template:DEC 617 ± 4 16.3
LEDA 166167 dI/dSph Template:RA Template:DEC 18
LEDA 166172 dSph Template:RA Template:DEC 18.5
LEDA 166175 dSph Template:RA Template:DEC 19.2
LEDA 166179 dSph Template:RA Template:DEC 18
NGC 4945 SB(s)cd Template:RA Template:DEC 563 ± 3 9.3
NGC 5102 SA0 Template:RA Template:DEC 468 ± 2 10.4
NGC 5206 SB(r)0 Template:RA Template:DEC 571 ± 10 11.6
NGC 5237 I0 Template:RA Template:DEC 361 ± 4 13.2
PGC 45104 IABm Template:RA Template:DEC
PGC 45717 I0 pec Template:RA Template:DEC 1853 ± 32 13.3
PGC 45916 dE Template:RA Template:DEC 784 ± 31 14.1
PGC 46663 IBm Template:RA Template:DEC 741 16.1
PGC 46680 Im Template:RA Template:DEC 16.6
PGC 47171 IABm Template:RA Template:DEC 516 ± 3 12.9
PGC 48515 dE Template:RA Template:DEC 17.6
PGC 48738 IB(s)m Template:RA Template:DEC 545 ± 2 14.0
PGC 49615 dS0/Im Template:RA Template:DEC 561 ± 32 14.8
Members of the M83 Subgroup
Name Type<ref name="ned"/> R.A. (J2000)<ref name="ned" /> Dec. (J2000)<ref name="ned" /> Redshift (km/s)<ref name="ned" /> Apparent Magnitude<ref name="ned" />
AM 1321-304 dIm Template:RA Template:DEC 487 ± 1 16.7
Centaurus A-dE2 dE/Im Template:RA Template:DEC 17.6
Centaurus A-dE4 dSph Template:RA Template:DEC 19.
HIDEEP J1336-3321 Template:RA Template:DEC 591 17.3
IC 4247 S Template:RA Template:DEC 274 ± 65 14.4
IC 4316 IBm pec Template:RA Template:DEC 674 ± 53 15.0
KK 208 dI Template:RA Template:DEC 381 14.3
LEDA 166163 dI Template:RA Template:DEC 571 ± 3 17.1
LEDA 166164 dSph Template:RA Template:DEC 17.6
M83 SAB(s)c Template:RA Template:DEC 513 ± 2 8.2
NGC 5253 Im pec Template:RA Template:DEC 407 ± 3 10.9
NGC 5264 IB(s)m Template:RA Template:DEC 478 ± 3 12.6
PGC 47885 Template:RA Template:DEC 13848 15.8
PGC 48111 Im Template:RA Template:DEC 587 ± 3 15.0
UGCA 365 Im Template:RA Template:DEC 573 ± 1 15.4

Additionally, ESO 219-010, PGC 39032, and PGC 51659 are listed as possibly being members of the Centaurus A Subgroup, and ESO 381-018, NGC 5408, and PGC 43048 are listed as possibly being members of the M83 Subgroup.<ref name="karachentsev2005" /> Although HIPASS J1337-39 is only listed as a possible member of the M83 Subgroup in the later list published by Karachentsev,<ref name="karachentsev2005" /> later analyses indicate that this galaxy is within the subgroup.<ref name="grossi2007">Template:Cite journal</ref> Saviane and Jerjen found that NGC 5011C has an optical redshift of 647 km/s and thus is a member of the Cen A group rather than of the distant Centaurus galaxy cluster as believed since 1983.

ReferencesEdit

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