M83 Group
Encyclopedia
The Centaurus A/M83 Group is a complex group of galaxies in the constellation
s 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 around Centaurus A
, a nearby radio galaxy
. The M83 Subgroup, at a distance of 14.9 Mly
(4.56 Mpc
), is centered around the Messier 83 (M83), a face-on spiral galaxy
.
This group is sometimes identified as one group and sometimes identified as two groups. 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.
The Centaurus A/M83 Group is part of the Virgo Supercluster
, the local supercluster of which the Local Group
is an outlying member.
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. 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. 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. Several optical surveys later identified 20 more candidate objects to the group.
In 2007, the Cen A group membership of NGC 5011C was established.
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.
and Messier 83.
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. Although HIPASS J1337-39 is only listed as a possible member of the M83 Subgroup in the later list published by Karachentsev, later analyses indicate that this galaxy is within the subgroup.
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.
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
s Hydra
Hydra (constellation)
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees. It has a long history, having been included among the 48 constellations listed by the 2nd century astronomer Ptolemy. It is commonly represented as a water snake...
, Centaurus
Centaurus
Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.-Stars:...
, and Virgo
Virgo (constellation)
Virgo is one of the constellations of the zodiac. Its name is Latin for virgin, and its symbol is . Lying between Leo to the west and Libra to the east, it is the second largest constellation in the sky...
. The group may be roughly divided into two subgroups. The Cen A Subgroup, at a distance of 11.9 Mly
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
(3.66 Mpc
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
), is centered around Centaurus A
Centaurus A
Centaurus A is a prominent galaxy in the constellation of Centaurus. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type and distance...
, a nearby radio galaxy
Radio galaxy
Radio galaxies and their relatives, radio-loud quasars and blazars, are types of active galaxy that are very luminous at radio wavelengths, with luminosities up to 1039 W between 10 MHz and 100 GHz. The radio emission is due to the synchrotron process...
. The M83 Subgroup, at a distance of 14.9 Mly
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
(4.56 Mpc
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
), is centered around the Messier 83 (M83), a face-on spiral galaxy
Spiral galaxy
A spiral galaxy is a certain kind of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as...
.
This group is sometimes identified as one group and sometimes identified as two groups. 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.
The Centaurus A/M83 Group is part of the Virgo Supercluster
Virgo Supercluster
The Virgo Supercluster or Local Supercluster is the irregular supercluster that contains the Virgo Cluster in addition to the Local Group, which in turn contains the Milky Way and Andromeda galaxies. At least 100 galaxy groups and clusters are located within its diameter of 33 megaparsecs...
, the local supercluster of which the Local Group
Local Group
The Local Group is the group of galaxies that includes Earth's galaxy, the Milky Way. The group comprises more than 30 galaxies , with its gravitational center located somewhere between the Milky Way and the Andromeda Galaxy...
is an outlying member.
Member identification
The brightest group members were frequently identified in early galaxy group identification surveys. 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 onoptical images from the UK Schmidt Telescope
UK Schmidt Telescope
The 1.2 metre UK Schmidt Telescope is operated by the Australian Astronomical Observatory , and located adjacent to the 3.9 metre Anglo-Australian Telescope at Siding Spring Observatory, Australia...
and followed these up in hydrogen line
Hydrogen line
The hydrogen line, 21 centimeter line or HI line refers to the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation is at the precise frequency of 1420.40575177 MHz, which is equivalent to the vacuum...
emission with the Parkes Radio Telescope and in the hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
-alpha spectral line
Spectral line
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from a deficiency or excess of photons in a narrow frequency range, compared with the nearby frequencies.- Types of line spectra :...
with the Siding Spring 2.3 m Telescope
Siding Spring 2.3 m Telescope
The 2.3 m Telescope at Siding Spring Observatory is operated by the Australian National University. The 2.3m Advanced Technology Telescope was constructed during the early 1980s and featured at-the-time radical features: an alt-az mount and co-rotating dome....
. This
identified 20 dwarf galaxies as members of the group. The HIPASS
HIPASS
The HI Parkes All Sky Survey was an astronomical survey for neutral atomic hydrogen . Data was taken between 1997 and 2002 using the Parkes Observatory. HIPASS covered 71% of the sky and identified 5317 sources emitting HI's signature wavelength...
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. 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. Several optical surveys later identified 20 more candidate objects to the group.
In 2007, the Cen A group membership of NGC 5011C was established.
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.
Member list
The table below lists galaxies that have been identified as associated with the Centaurus A/M83 Group by I. D. Karachentsev and collaborators. Note that Karachentsev divides this group into two subgroups centered around Centaurus ACentaurus A
Centaurus A is a prominent galaxy in the constellation of Centaurus. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type and distance...
and Messier 83.
| Name | Type | R.A. Right ascension Right ascension is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.-Explanation:... (J2000) |
Dec. Declination In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and... (J2000) |
Redshift Redshift In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum... (km/s Second The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock.... ) |
Apparent Magnitude Apparent magnitude The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere... |
|---|---|---|---|---|---|
| Cen 7 | Sph | 17.3 | |||
| Cen N | 17.5 | ||||
| Centaurus A Centaurus A Centaurus A is a prominent galaxy in the constellation of Centaurus. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type and distance... (NGC 5128) |
S0 pec | 547 ± 5 | 7.8 | ||
| Centaurus A-dE1 | dSph | 19.3 | |||
| Centaurus A-dE3 | dE | 17.1 | |||
| HIPASS J1337-39 | Im | 492 ± 4 | 16.5 | ||
| HIPASS J1348-37 | 581 ± 8 | 16.9 | |||
| HIPASS J1351-47 | 529 ± 6 | ||||
| KKs 51 | E/Sph | 16.7 | |||
| KKs 55 | Sph | 18.5 | |||
| KKs 57 | Sph | 18.1 | |||
| LEDA 166152 | dI | 617 ± 4 | 16.3 | ||
| LEDA 166167 | dI/dSph | 18 | |||
| LEDA 166172 | dSph | 18.5 | |||
| LEDA 166175 | dSph | 19.2 | |||
| LEDA 166179 | dSph | 18 | |||
| NGC 4945 NGC 4945 NGC 4945 is a spiral galaxy in the constellation Centaurus. It is thought to be quite similar to the Milky Way Galaxy, but X-ray observations show that NGC 4945 has an unusual, energetic, Seyfert 2 nucleus that might house a large black hole... |
SB(s)cd | 563 ± 3 | 9.3 | ||
| NGC 5102 NGC 5102 NGC 5102 is a galaxy in the M83 group of galaxies. It was discovered by John Frederick William Herschel in 1835.-Distance measurements:At least two techniques have been used to measure distances to NGC 5102. The surface brightness fluctuations distance measurement technique estimates distances to... |
SA0 | 468 ± 2 | 10.4 | ||
| NGC 5206 | SB(r)0 | 571 ± 10 | 11.6 | ||
| NGC 5237 | I0 | 361 ± 4 | 13.2 | ||
| PGC 45104 | IABm | ||||
| PGC 45717 | I0 pec | 1853 ± 32 | 13.3 | ||
| PGC 45916 | dE | 784 ± 31 | 14.1 | ||
| PGC 46663 | IBm | 741 | 16.1 | ||
| PGC 46680 | Im | 16.6 | |||
| PGC 47171 | IABm | 516 ± 3 | 12.9 | ||
| PGC 48515 | dE | 17.6 | |||
| PGC 48738 | IB(s)m | 545 ± 2 | 14.0 | ||
| PGC 49615 | dS0/Im | 561 ± 32 | 14.8 | ||
| Name | Type | R.A. Right ascension Right ascension is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.-Explanation:... (J2000) |
Dec. Declination In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and... (J2000) |
Redshift Redshift In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum... (km/s Second The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock.... ) |
Apparent Magnitude Apparent magnitude The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere... |
|---|---|---|---|---|---|
| AM 1321-304 | dIm | 487 ± 1 | 16.7 | ||
| Centaurus A-dE2 | dE/Im | 17.6 | |||
| Centaurus A-dE4 | dSph | 19. | |||
| HIDEEP J1336-3321 | 591 | 17.3 | |||
| IC 4247 | S | 274 ± 65 | 14.4 | ||
| IC 4316 | IBm pec | 674 ± 53 | 15.0 | ||
| KK 208 | dI | 381 | 14.3 | ||
| LEDA 166163 | dI | 571 ± 3 | 17.1 | ||
| LEDA 166164 | dSph | 17.6 | |||
| M83 | SAB(s)c | 513 ± 2 | 8.2 | ||
| NGC 5253 NGC 5253 NGC 5253 is an irregular galaxy in the constellation Centaurus. It was discovered by John Frederick William Herschel on 15 March 1787.-Galaxy group information:... |
Im pec | 407 ± 3 | 10.9 | ||
| NGC 5264 | IB(s)m | 478 ± 3 | 12.6 | ||
| PGC 47885 | 13848 | 15.8 | |||
| PGC 48111 | Im | 587 ± 3 | 15.0 | ||
| UGCA 365 | Im | 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
NGC 5408
NGC 5408 is an irregular galaxy in the constellation Centaurus. The galaxy was discovered by John Frederick William Herschel in 1834.-Galaxy group information:...
, and PGC 43048 are listed as possibly being members of the M83 Subgroup. Although HIPASS J1337-39 is only listed as a possible member of the M83 Subgroup in the later list published by Karachentsev, later analyses indicate that this galaxy is within the subgroup.
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.