The discovery of a shell-like event in the O-type star HD 120678
Abstract
Aims: We report the detection of a shell-like event in the Oe-type star HD 120678.
Methods: HD 120678 has been intensively observed as part of a high-resolution spectroscopic monitoring program of southern Galactic O stars and Wolf-Rayet stars of the nitrogen sequence.
Results: An optical spectrogram of HD 120678 obtained in June 2008 shows strong H and He i absorption lines instead of the double-peaked emission profiles observed both previously and subsequently, as well as a variety of previously undetected absorption features, mainly of O ii, Si iii and Fe iii. Photometric data reveal that the development of the absorption spectrum coincided with a remarkable dip in the V-band lightcurve. The "shell phase" of HD 120678 did not persist for very long: the V magnitude recovered its previous average value in fewer than 120 days, whereas H and He emission lines became detectable one year later. Similar spectral variations have been observed in a few Be stars, and they are usually interpreted as changes in the circumstellar disk.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 2012
- DOI:
- 10.1051/0004-6361/201118725
- Bibcode:
- 2012A&A...546A..92G
- Keywords:
-
- binaries: spectroscopic;
- stars: early-type;
- stars: emission-line;
- Be;
- stars: individual: HD 120678