| NGC 3557 | |
|---|---|
 The elliptical galaxy NGC 3557 | |
| Observation data (J2000epoch) | |
| Constellation | Centaurus |
| Right ascension | 11h 09m 57.6396s[1] |
| Declination | −37° 32′ 21.037″[1] |
| Redshift | 0.010270[1] |
| Heliocentric radial velocity | 3079 ± 6 km/s[1] |
| Distance | 163.5 ± 11.5 Mly (50.12 ± 3.53 Mpc)[1] |
| Apparent magnitude (V) | 10.4[1] |
| Characteristics | |
| Type | E3[1] |
| Size | ~246,200 ly (75.48 kpc) (estimated)[1] |
| Apparent size (V) | 4.0′ × 3.0′[1] |
| Other designations | |
| 2MASX J11095583-3732345,MCG -06-25-005,PGC 33871, ESO 377- G 016[1] | |
NGC 3557 is a largeelliptical galaxy in theconstellation ofCentaurus. Its velocity with respect to thecosmic microwave background is 3398 ± 23 km/s, which corresponds to aHubble distance of 50.12 ± 3.53Mpc (~163 millionlight-years).[1] However, 20non-redshift measurements give a distance of 32.905 ± 2.289 (~107 million light-years).[2] The galaxy was discovered by British astronomerJohn Herschel on 21 April 1835.[3]
TheSIMBAD database lists NGC 3557 as aSeyfert I Galaxy, i.e. it has aquasar-like nuclei with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable.[4] Additionally,NED lists NGC 3557 as aLINER galaxy, i.e. a galaxy whose nucleus has an emission spectrum characterized by broad lines of weakly ionized atoms.[1]
Onesupernova has been observed in NGC 3557: SN 2023bpx (type Ia, mag. 17) was discovered by theBackyard Observatory Supernova Search (BOSS) on 12 February 2023.[5]
NGC 3557 is the largest and brightest galaxy in agroup of galaxies that bears its name. The NGC 3557 group (also known asLGG 229) includes at least eleven galaxies, includingNGC 3533,NGC 3557B,NGC 3564,NGC 3568 andNGC 3573.[6]
Media related toNGC 3557 at Wikimedia Commons
