NGC 2775
Galaxy in the constellation Cancer / From Wikipedia, the free encyclopedia
NGC 2775, also known as Caldwell 48, is a spiral galaxy in the constellation Cancer. It is 67 million light-years (20.5 megaparsecs)[3] away from the Milky Way. It was discovered by William Herschel in 1783. NGC 2775 belongs to the Antlia-Hydra Cluster[9] of galaxies and is the most prominent member of the NGC 2775 Group, a small galaxy group in the Virgo Super-cluster, along with the Local Group. Other members of the NGC 2775 Group include NGC 2777 and UGC 4781.[10]
NGC 2775 | |
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Observation data (J2000 epoch) | |
Constellation | Cancer |
Right ascension | 09h 10m 20.112s[1] |
Declination | +07° 02′ 16.53″[1] |
Redshift | 1,316.4±13.4 km/s[2] |
Distance | 67 Mly (20.5 Mpc)[3] |
Apparent magnitude (V) | 10.4[4] |
Characteristics | |
Type | SAa[5] or SA(r)ab[6] |
Apparent size (V) | 4.3′ × 3.3′[6] |
Other designations | |
UGC 4820,[7] PGC 25861,[8] Caldwell 48 |
This object has a morphological classification of SA(r)ab,[6] which indicates an unbarred spiral galaxy (SA) with a prominent ring structure (r) and flocculent,[11] tightly wound spiral arms (ab).[12] The galaxy is inclined by an angle of 44° to the line of sight from the Earth.[6] The galactic nucleus is not active[2] and the large nuclear bulge, which extends out to an angular radius of 0.4′,[12] is relatively gas free.[11] An explanation for the latter could be a high supernova rate.[6] Although star formation is taking place in the dusty outer ring,[12] NGC 2775 does not display any current starburst activity,[13] and the galactic nucleus is virtually free of any star formation whatsoever.[11]
The galaxy's hydrogen tail feature indicates a past interaction with a faint companion.[6] A satellite galaxy appears to have orbited NGC 2775 multiple times, losing mass as it does so and creating faint, shell-like structures.[12] Nearby irregular galaxy NGC 2777 displays a tidal tail of hydrogen gas that points back to NGC 2775, suggesting the two may be linked.[14]
SN1993z is the only supernova known to have occurred in NGC 2775. It was detected on September 23, 1993, at a magnitude of 13.9, and was classified as a Type Ia supernova.[15] By September 25, spectral analysis showed that it had peaked four weeks earlier.[16]