Detection of Preshock Dense Circumstellar Material of SN 1978K
Abstract
The supernova SN 1978K has been noted for its lack of emission lines broader than a few thousand kilometers per second since its discovery in 1990. Modeling of the radio spectrum of the peculiar SN 1978K indicates the existence of H II absorption along the line of sight. To determine the nature of this absorbing region, we have obtained a high-dispersion spectrum of SN 1978K at the wavelength range 6530-6610 Å. The spectrum shows not only the moderately broad Hα emission of the supernova ejecta but also narrow nebular Hα and [N II] emission. The high [N II] λ6583/Hα ratio, 0.8-1.3, suggests that this radio-absorbing region is a stellar ejecta nebula. The expansion velocity and emission measure of the nebula are consistent with those seen in ejecta nebulae of luminous blue variables. Previous low-dispersion spectra have detected a strong [N II] λ5755 line, indicating an electron density of (3-12)×105 cm-3. We argue that this stellar ejecta nebula is probably part of the preshock dense circumstellar envelope of SN 1978K. We further suggest that SN 1997ab may represent a young version of SN 1978K.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1999
- DOI:
- 10.1086/311866
- arXiv:
- arXiv:astro-ph/9812240
- Bibcode:
- 1999ApJ...512L..51C
- Keywords:
-
- STARS: CIRCUMSTELLAR MATTER;
- GALAXIES: INDIVIDUAL: NGC NUMBER: NGC 1313;
- STARS: MASS LOSS;
- STARS: SUPERNOVAE: INDIVIDUAL: ALPHANUMERIC: SN 1978K;
- Stars: Circumstellar Matter;
- Galaxies: Individual: NGC Number: NGC 1313;
- Stars: Mass Loss;
- Stars: Supernovae: Individual: Alphanumeric: SN 1978K;
- Astrophysics
- E-Print:
- 12 pages, 1 figure, accepted for publication in the ApJ Letters