| Arp 240 | |
|---|---|
 Arp 240. The two galaxies are NGC 5257 (right) and NGC 5258 (left). | |
| Observation data (J2000 epoch) | |
| Constellation | Virgo |
| Right ascension | Right: 13h 39m 52.3s [1] Left: 13h 39m 57.7s [2] |
| Declination | Right: +00° 50′ 22″ [1] Left: +00° 49′ 51″ [2] |
| Redshift | Right: 6798 ± 9 km/s [1] Left: 6757 ± 1 km/s [2] |
| Distance | Right: 345.1 Mly (105.8 Mpc) [3] Left: 342.1 Mly (104.9 Mpc) [3] |
| Apparent magnitude (V) | 12.9 / 12.9 [1] [2] |
| Characteristics | |
| Type | Right: SAB(s)b pec [1] Left: SA(s)b pec [2] |
| Apparent size (V) | Right: 1.8′ × 0.9′ [1] Left: 1.7′ × 1.1′ [1] |
| Notable features | Interacting galaxies |
| Other designations | |
| Right: NGC 5257, UGC 8641, PGC 48330, VV 55b [1] Left: NGC 5258, UGC 8645, PGC 48338, VV 55a [1] | |
Arp 240 is a pair of interacting spiral galaxies located in the constellation Virgo. The two galaxies are listed together as Arp 240 in the Atlas of Peculiar Galaxies. [4] The galaxy on the right is known as NGC 5257, while the galaxy on the left is known as NGC 5258. Both galaxies are distorted by the gravitational interaction, and both are connected by a tidal bridge, as can be seen in images of these galaxies.
One supernova has been observed in NGC 5258: SN 2020dko (type Ia, mag. 19). [5]
