The Eridanus Cluster is a galaxy cluster roughly 23 Mpc (75 Mly) from Earth, containing about 73 main galaxies and about 200 total galaxies. About 30% have Hubble classifications of elliptical or S0 and the remaining 70% are spiral or irregular.[2] These galaxies reside in smaller groups which are all loosely gravitationally bound to each other, suggesting that the system is still condensing from the Hubble flow and may eventually form a cluster of about 1014 M☉. A low velocity dispersion compared to that of, for example, the Coma cluster, supports this hypothesis.[3] The Eridanus Cluster is located in the constellation Eridanus near the Fornax Cluster, and is sometimes called the "Fornax II Cluster".[4]
| Eridanus Cluster | |
|---|---|
| Observation data (Epoch J2000) | |
| Constellation(s) | Eridanus |
| Right ascension | 03h 28m 13.8s[1] |
| Declination | −20° 44′ 40″[1] |
| Brightest member | NGC 1232 (B) |
| Number of galaxies | ~200[2] |
| Velocity dispersion | 261 km/s[3] |
| Redshift | 0.005570[1] |
| Distance | 23 Mpc (75 Mly)[1] |
| ICM temperature | ~107 K (~1 keV)[2] |
| Binding mass | ~1014[3] M☉ |
| X-ray flux | 0.105 mCrab[2] |
| Other designations | |
| Fornax II Cluster,[4] de Vaucouleurs Group 31[5] | |
Table of galaxies
edit| Name of the galaxy |
Right ascension for epoch J2000 |
Declination for epoch J2000 |
Blue apparent magnitude of the galaxy |
Galaxy type: E=Elliptical; S0=Lenticular; Sa, Sb, Sc, Sd=Spiral (degree of woundedness of spiral arms); SBa, SBb, SBc, SBd=Barred Spiral; SAB= Intermediate Spiral (between barred and unbarred); Sm, SBm, Irr=Irregular; (r),(rs)=Ring Structure |
Angular diameter of the galaxy (arcminutes) |
Diameter of the galaxy (thousands of light years) |
Recessional velocity (km/s) of the galaxy relative to the cosmic microwave background |
|---|---|---|---|---|---|---|---|
| Name | RA equatorial coordinates |
Dec equatorial coordinates |
Blue Mag |
Type | Size (arcmin) |
Size (kly) |
RV (km/s) |
| ESO 547-09 | 03 06.0 | –19 23 | 16.8 | Irr | 1.3 | 35 | 1509 |
| ESO 547-12 | 03 09.6 | –17 50 | 16.5 | Scd | 1.5 | 35 | 1837 |
| NGC 1232 | 03 09.8 | –20 35 | 10.7 | SAB(rs)c | 6.9 | 170 | 1517 |
| IC 1898 | 03 10.3 | –22 24 | 13.7 | SBc | 3.4 | 85 | 1164 |
| ESO 547-20 | 03 13.0 | –17 56 | 16.0 | SBm | 1.2 | 30 | 1825 |
| NGC 1258 | 03 14.1 | –21 46 | 13.9 | SBc | 1.3 | 30 | 1340 |
| NGC 1297 | 03 19.2 | –19 06 | 13.5 | E | 2.0 | 50 | 1395 |
| NGC 1300 | 03 19.7 | –19 25 | 11.2 | SBbc | 6.0 | 110 | 1421 |
| NGC 1315 | 03 23.1 | –21 23 | 14.0 | S0 | 1.5 | 35 | 1534 |
| PGC 12680 | 03 23.4 | –19 17 | ? | Irr | 1.3 | 30 | 1400 |
| ESO 548-05 | 03 23.8 | –19 45 | 14.7 | SBm | 1.5 | 35 | 1690 |
| NGC 1325 | 03 24.4 | –21 33 | 12.3 | SBbc | 4.7 | 115 | 1446 |
| NGC 1325A | 03 24.8 | –21 20 | 13.6 | SBcd | 1.8 | 45 | 1188 |
| ESO 548-16 | 03 26.0 | –21 20 | 15.6 | Scd | 1.7 | 40 | 1977 |
| NGC 1332 | 03 26.3 | –21 20 | 11.4 | E | 4.2 | 105 | 1383 |
| ESO 548-21 | 03 27.6 | –21 14 | 14.7 | SBd | 2.0 | 50 | 1541 |
| ESO 548-25 | 03 29.0 | –22 09 | 15.0 | SBa | 1.3 | 30 | 1542 |
| NGC 1345 | 03 29.5 | –17 47 | 14.3 | SBc | 1.4 | 35 | 1385 |
| ESO 481-30 | 03 29.6 | –23 21 | 15.5 | Scd | 1.5 | 35 | 1504 |
| NGC 1347 | 03 29.7 | –22 17 | 13.9 | SBc | 1.4 | 35 | 1624 |
| ESO 548-28 | 03 30.6 | –17 56 | 14.0 | S0 | 1.3 | 35 | 1360 |
| ESO 548-29 | 03 30.8 | –21 03 | 14.3 | SBbc | 1.1 | 30 | 1175 |
| NGC 1353 | 03 32.1 | –20 49 | 12.4 | SBb | 3.5 | 85 | 1390 |
| ESO 548-32 | 03 32.3 | –17 43 | 15.8 | SBm | 1.6 | 40 | 1815 |
| ESO 548-33 | 03 32.5 | –18 57 | 14.5 | S0 | 1.3 | 35 | 1552 |
| ESO 548-34 | 03 33.0 | –21 05 | 14.6 | SBc | 1.1 | 30 | 1610 |
| ESO 482-05 | 03 33.0 | –24 08 | 15.2 | SBcd | 2.1 | 50 | 1783 |
| NGC 1357 | 03 33.2 | –13 39 | 12.4 | Sab | 3.2 | 85 | 2018 |
| IC 1952 | 03 33.4 | –23 43 | 13.5 | SBbc | 2.5 | 60 | 1683 |
| IC 1953 | 03 33.7 | –21 29 | 12.7 | SBc | 2.6 | 65 | 1733 |
| NGC 1359 | 03 33.8 | –19 29 | 13.0 | SBm | 2.1 | 55 | 1833 |
| NGC 1362 | 03 33.9 | –20 17 | 14.2 | S0 | 1.2 | 30 | 1085 |
| ESO 548-44 | 03 34.3 | –19 25 | 14.2 | S0 | 1.3 | 35 | 1561 |
| ESO 548-47 | 03 34.7 | –19 02 | 14.1 | S0 | 2.5 | 60 | 1472 |
| NGC 1367 | 03 35.0 | –24 56 | 11.6 | SBa | 5.6 | 140 | 1344 |
| NGC 1370 | 03 35.2 | –20 22 | 13.9 | E | 1.5 | 35 | 933 |
| IC 1962 | 03 35.6 | –21 18 | 14.8 | SBd | 2.5 | 60 | 1670 |
| ESO 482-11 | 03 36.3 | –25 36 | 14.7 | Sbc | 1.4 | 35 | 1469 |
| NGC 1377 | 03 36.7 | –20 54 | 13.8 | S0 | 1.7 | 45 | 1645 |
| NGC 1385 | 03 37.5 | –24 30 | 11.5 | SBc | 3.7 | 90 | 1373 |
| NGC 1383 | 03 37.7 | –18 20 | 13.8 | S0 | 1.7 | 40 | 1828 |
| ESO 482-17 | 03 37.7 | –22 55 | 14.9 | Sab | 1.3 | 30 | 1330 |
| NGC 1390 | 03 37.9 | –19 00 | 14.9 | SBa | 1.3 | 35 | 1078 |
| NGC 1395 | 03 38.5 | –23 02 | 10.7 | E | 5.6 | 140 | 1577 |
| NGC 1398 | 03 38.9 | –26 20 | 10.5 | SB(r)ab | 7.1 | 135 | 1289 |
| NGC 1403 | 03 39.2 | –22 23 | 14.1 | E | 1.3 | 30 | 1751 |
| NGC 1401 | 03 39.4 | –22 43 | 13.7 | S0 | 1.9 | 50 | 1406 |
| NGC 1400 | 03 39.5 | –18 41 | 12.3 | E | 2.3 | 60 | 415 |
| ESO 548-63 | 03 39.6 | –20 01 | 15.1 | Sbc | 1.4 | 35 | 1846 |
| ESO 548-65 | 03 40.0 | –19 22 | 15.3 | Sa | 1.4 | 35 | 1102 |
| IC 343 | 03 40.1 | –18 27 | 14.3 | S0 | 1.4 | 35 | 1730 |
| NGC 1407 | 03 40.2 | –18 35 | 10.9 | E | 5.1 | 125 | 1650 |
| ESO 548-68 | 03 40.3 | –18 56 | 14.3 | E | 1.3 | 35 | 1636 |
| NGC 1412 | 03 40.5 | –26 52 | 14.7 | S0 | 1.4 | 35 | 1675 |
| ESO 548-70 | 03 40.7 | –22 17 | 15.4 | SBcd | 1.6 | 40 | 1615 |
| ESO 482-32 | 03 40.7 | –26 47 | 15.9 | Irr | 1.2 | 30 | 1621 |
| NGC 1415 | 03 40.9 | –22 34 | 12.8 | Sa | 3.3 | 80 | 1451 |
| NGC 1414 | 03 41.0 | –21 43 | 14.6 | SBbc | 1.6 | 40 | 1464 |
| ESO 482-35 | 03 41.2 | –23 50 | 14.2 | SBab | 1.8 | 45 | 1756 |
| NGC 1422 | 03 41.5 | –21 41 | 14.2 | SBab | 2.3 | 55 | 1514 |
| IC 346 | 03 41.7 | –18 16 | 13.9 | S0 | 1.9 | 45 | 1830 |
| ESO 548-79 | 03 41.9 | –18 54 | 14.8 | Sa | 1.1 | 30 | 1914 |
| ESO 548-82 | 03 42.7 | –17 30 | 15.4 | Sbc | 1.1 | 30 | 1590 |
| NGC 1426 | 03 42.8 | –22 06 | 12.7 | E | 2.5 | 60 | 1296 |
| ESO 549-02 | 03 43.0 | –19 01 | 14.9 | SBm | 1.3 | 30 | 988 |
| ESO 549-06 | 03 43.6 | –21 14 | 15.7 | Irr | 1.3 | 30 | 1490 |
| NGC 1439 | 03 44.8 | –21 55 | 12.4 | E | 2.6 | 65 | 1577 |
| NGC 1440 | 03 45.0 | –18 16 | 12.9 | S0 | 2.2 | 55 | 1403 |
| NGC 1438 | 03 45.3 | –23 00 | 13.3 | SBa | 2.0 | 50 | 1438 |
| NGC 1452 | 03 45.4 | –18 38 | 12.9 | Sa | 2.3 | 60 | 1619 |
| ESO 549-18 | 03 48.2 | –21 28 | 13.3 | SBc | 2.5 | 60 | 1473 |
| ESO 482-46 | 03 49.7 | –27 00 | 13.7 | Sc | 3.5 | 90 | 1422 |
| ESO 482-49 | 03 52.4 | –23 03 | 15.3 | Sc | 1.1 | 30 | 1377 |
| NGC 1482 | 03 54.6 | –20 30 | 13.3 | S0 | 2.2 | 55 | 1753 |
See also
editReferences
edit- ^ a b c d "Eridanus Cluster". NASA/IPAC Extragalactic Database (NED). Retrieved 2012-02-25.
- ^ a b c d Omar, A.; Dwarakanath, K. S. (March 2005). "GMRT HI Observations of the Eridanus Group of Galaxies I" (PDF). Journal of Astrophysics and Astronomy. 26 (1): 1–33. arXiv:astro-ph/0503536. Bibcode:2005JApA...26....1O. doi:10.1007/BF02702451. S2CID 7451092. Retrieved 2012-02-25.
- ^ a b c Willmer, C. N. A.; Rocardi, P.; da Costa, L. Nicolaci; Pellegrini, P. S. (November 1989). "Studies of nearby poor clusters – The Eridanus group" (PDF). Astronomical Journal. 98 (Nov. 1989): 1531–1541. Bibcode:1989AJ.....98.1531W. doi:10.1086/115236. ISSN 0004-6256. Retrieved 2012-02-25.
- ^ a b atlasoftheuniverse.com
- ^ Chincarini, G.; Rood, H. J.; Welch, G. A. (March 1975). "A re-analysis of the dynamics of the nearby groups of galaxies". Monthly Notices of the Royal Astronomical Society. 170 (Mar. 1975): 441–445. Bibcode:1975MNRAS.170..441C. doi:10.1093/mnras/170.3.441. A&AA ID. AAA013.160.006.