Arp 7
Galaxy in the constellation Hydra
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Arp 7 (PGC 24836) is a spiral galaxy in the constellation Hydra.[1] Redshift-independent measurements of its distance vary widely, from 5.9 to 83.7 megaparsecs (19.24 to 273.0 million light-years).[3] Its morphological classification is SB(rs)bc,[3] meaning it is a barred spiral galaxy with some ring-like structure.
Right ascension8h 50m 30.0s[2]
Declination−16° 37′ 00″[2]
| Arp 7 | |
|---|---|
Arp 7 by PanSTARRS | |
| Observation data (J2000 epoch) | |
| Constellation | Hydra[1] |
| Right ascension | 8h 50m 30.0s[2] |
| Declination | −16° 37′ 00″[2] |
| Redshift | 0.018620±0.000002[3] |
| Heliocentric radial velocity | 5,582±1 km/s[3] |
| Galactocentric velocity | 5,384±8 km/s[4][3] |
| Distance | 103.9 ± 146.4 Mly (31.853 ± 44.901 Mpc)[3] |
| Apparent magnitude (V) | 14.5[3] |
| Characteristics | |
| Type | SB(rs)bc: HII[3] |
| Size | 40,737 ly (12.49 kpc) (diameter; 25.0 B-mag arcsec−2)[3][a] 28,767 ly × 26,451 ly (8.82 kpc × 8.11 kpc) (diameter; "total" magnitude)[3][a] |
| Apparent size (V) | 1.3′ × 1.0′ [3] |
| Other designations | |
| PGC 024836,[3] APG 7[2] | |
Arp 7 was imaged by Halton Arp and included in his Atlas of Peculiar Galaxies under the category of 'split arm' galaxies.[5] Five other galaxies are also included in this section of the atlas: Arp 8 (NGC 497), Arp 9 (NGC 2523), Arp 10 (UGC 1775), Arp 11 (UGC 717), and Arp 12 (NGC 2608).