| NGC 3557 | |
|---|---|
 The elliptical galaxy NGC 3557. | |
| Observation data (J2000 epoch) | |
| Constellation | Centaurus |
| Right ascension | 11h 09m 57.642s[1] |
| Declination | −37° 32′ 20.958″[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' x 3.0'[1] |
| Other designations | |
| 2MASX J11095583-3732345, MCG -06-25-005, PGC 33871, ESO 377- G 016[1] | |
NGC 3557 is a elliptical galaxy in the constellation of Centaurus. Its velocity with respect to the cosmic microwave background is 3398 ± 23 km/s, which corresponds to a Hubble distance of 50.12 ± 3.53 Mpc (∼163 million light-years).[1] However, 20 non-redshift measurements give a distance of 32.905 ± 2.289 (∼107 million light-years).[2] The galaxy was discovered by British astronomer John Herschel on 21 April 1835.[3]
The SIMBAD database lists NGC 3557 as a Seyfert I Galaxy, i.e. it has a quasar-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 a LINER galaxy, i.e. a galaxy whose nucleus has an emission spectrum characterized by broad lines of weakly ionized atoms.[1]
One supernova has been observed in NGC 3557: SN 2023bpx (type Ia, mag. 17).[5]
- ^ a b c d e f g h i j k l "NASA/IPAC Extragalactic Database". Results for NGC 3557. Retrieved 11 August 2024.
- ^ "Distance Results for NGC 3557". NASA/IPAC EXTRAGALACTIC DATABASE. NASA. Retrieved 11 August 2024.
- ^ Seligman, Courtney. "NGC 3557". Celestial Atlas. Retrieved 11 August 2024.
- ^ "NGC 3557". SIMBAD astronomical database. Strasbourg Astronomy Data Centre. Retrieved 11 August 2024.
- ^ "SN 2023bpx". Transient Name Server. IAU. Retrieved 11 August 2024.