An Interstellar Conduction Front within a Wolf-Rayet Ring Nebula Observed with the Goddard High Resolution Spectrograph
Abstract
With the High Resolution Spectrograph aboard the Hubble Space Telescope we obtained high signal-to-noise ratio (S/N >~ 200-600 per 17 km s-1 resolution element) spectra of narrow absorption lines toward the Wolf-Rayet star HD 50896. The ring nebula S308 that surrounds this star is thought to be caused by a pressure-driven bubble bounded by circumstellar gas (most likely from a red supergiant or luminous blue variable progenitor) pushed aside by a strong stellar wind. Our observation has shown for the first time that blueshifted (~70 km s-1 relative to the star) absorption components of C IV and N V arise in a conduction front between the hot interior of the bubble and the cold shell of swept-up material. These lines set limits on models of the conduction front. Nitrogen in the shell appears to be overabundant by a factor 10.
The P Cygni profiles of N V and C IV are variable, possibly because of a suspected binary companion to HD 50896.- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1997
- DOI:
- 10.1086/303799
- arXiv:
- arXiv:astro-ph/9610186
- Bibcode:
- 1997ApJ...478..638B
- Keywords:
-
- ISM: Bubbles;
- ISM: Individual: Alphanumeric: S308;
- Line: Profiles;
- Stars: Individual: Henry Draper Number: HD 50896;
- Stars: Wolf-Rayet;
- Astrophysics
- E-Print:
- 32 pages, Latex, to appear in the Astrophysical Journal, April, 1997