Spectroscopy of the candidate luminous blue variable at the center of the ring nebula G79.29+0.46
Abstract
We report optical and near-infrared spectra of the central star of the radio source G79.29+0.46, a candidate luminous blue variable. The spectra contain numerous narrow (FWHM < 100 km s-1) emission lines of which the low-lying hydrogen lines are the strongest, and resemble spectra of other LBVc's and B[e] supergiants. A few prominent infrared lines are unidentified. The terminal wind speed is determined from Hα to be 110 km s-1. The strength of Hα implies the presence of a very dense wind. Extended emission from Hα and [N ii] was detected but appears to be associated with the Cygnus X region rather than the radio source. Both diffuse interstellar bands and interstellar absorption lines are present in the optical spectrum of the central star, suggesting that there are both diffuse and molecular cloud components to the extinction and implying a minimum distance of 1 kpc and minimum luminosity of ~ 105 Lsun for the star. The new spectra and their analysis indicate a low excitation, dense, and slowly expanding wind and support the LBVc classification.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 2000
- DOI:
- arXiv:
- arXiv:astro-ph/0008293
- Bibcode:
- 2000A&A...362..236V
- Keywords:
-
- STARS: CIRCUMSTELLAR MATTER;
- STARS: EARLY-TYPE;
- STARS: EVOLUTION;
- STARS: INDIVIDUAL: G79.29+0.46;
- STARS: MASS-LOSS;
- STARS: VARIABLES: GENERAL;
- Astrophysics
- E-Print:
- Accepted for publication in Astronomy and Astrophysics, 7 PostScript figures, 5 tables