SN 1998S
Supernova in the constellation Ursa Major
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SN 1998S was a type IIn supernova that was detected in NGC 3877 in March 1998. At the time of discovery, SN 1998S was the brightest type IIn event observed,[2] although later outshone by SN 2010jl.[3]
(detected 2 March 1998 by Z. Wan)
R-band image of SN 1998S in NGC 3877 obtained on 1998 March 16.1 ut at t he Jacobus Kapteyn Telescope (JKT), La Palma (north is up and east is to the left).[1] | |
| Event type | Supernova |
|---|---|
| IIn | |
| Date | c. 50.5 million years ago (detected 2 March 1998 by Z. Wan) |
| Constellation | Ursa Major |
| Right ascension | 11h 46m 06.25s |
| Declination | +47° 28' 55.5" |
| Epoch | J2000.0 |
| Galactic coordinates | 150.7467 +65.9637 |
| Distance | c. 50.5 million ly |
| Host | NGC 3877 |
| Progenitor type | maybe Red supergiant |
| Colour (B-V) | ~ 0.2 mag |
| Notable features | SN 1998S, AAVSO 1140+48 |
| Peak apparent magnitude | 12 mag |
| Other designations | SN 1998S, 2MASS J11460613+4728553, AAVSO 1140+48 |
It was discovered on 1998 March 2.68 UT in NGC 3877 by Z. Wan at a broadband (unfiltered) optical magnitude of +15.2.
Its spectrum showed prominent H and He emission lines with narrow peaks and broad wings, superimposed on a blue continuum. These narrow lines indicate the presence of a dense circumstellar medium (CSM) in the vicinity of the supernova. The high luminosity of SN1998S is due to the interaction of fast material (ejecta) with previously-expelled slowly-expanding material (CSM), which can more effectively convert kinetic energy of ejecta into radiation energy.[4]
