An unusual supernova remnant with broad emission lines near NGC 4449.
Abstract
Optical spectrophotometry between 3500 and 6900 A of a radio source seen in the outer regions of the Ir I galaxy NGC 4449 reveals a spectrum of extremely unusual character. Two kinematic components appear in the emission lines. One is a narrow-line component typified by velocity widths less than 500 km/s and line ratios which are similar to numerous H II regions nearby in most respects. The other is a broad-line component (velocity width about 4000 km/s) seen only in the forbidden lines of O I and O III and perhaps the forbidden auroral lines of S II. The broad-line spectral component resembles that of the fast-moving knots seen in Cas A and N132 D in the LMC. However, the radio luminosity of the source is much greater than that of other SNRs and, unlike other known remnants for which line luminosities are known, the majority of its radiated energy apparently emerges in its optical forbidden lines and not in its continuous spectrum.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1978
- DOI:
- 10.1086/182819
- Bibcode:
- 1978ApJ...226L...7B
- Keywords:
-
- Astronomical Photometry;
- Emission Spectra;
- Radio Sources (Astronomy);
- Supernova Remnants;
- Forbidden Bands;
- H Ii Regions;
- Nebulae;
- Oxygen Spectra;
- Spectral Line Width;
- Astronomy;
- Emission Lines:Supernova Remnants;
- Irregular Galaxies:Supernova Remnants;
- Radio Sources:Spectrophotometry;
- Radio Sources:Supernova Remnants