NGC 3557


NGC 3557 is a large 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. However, 20 non-redshift measurements give a distance of 32.905 ± 2.289. The galaxy was discovered by British astronomer John Herschel on 21 April 1835.
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. 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.

Supernova

One supernova has been observed in NGC 3557.SN 2023bpx was discovered by the Backyard Observatory Supernova Search on 12 February 2023.

NGC 3557 Group

NGC 3557 is the largest and brightest galaxy in a group of galaxies that bears its name. The NGC 3557 group includes at least eleven galaxies, including NGC 3533, NGC 3557B, NGC 3564, NGC 3568 and NGC 3573.