A new observational tracer for high-density disc-like structures around B[e] supergiants
The disc formation mechanism of B[e] supergiants is one of the puzzling phenomena in massive star evolution. Rapid stellar rotation seems to play an important role for the non-spherically symmetric mass-loss leading to a high-density disc- or ring-like structure of neutral material around these mass...
| Authors: | , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2012 |
| Country: | Argentina |
| Institution: | Universidad Nacional de La Plata |
| Repository: | SEDICI (UNLP) |
| Language: | English |
| OAI Identifier: | oai:sedici.unlp.edu.ar:10915/84658 |
| Online Access: | http://sedici.unlp.edu.ar/handle/10915/84658 |
| Access Level: | Open access |
| Keyword: | Ciencias Astronómicas Circumstellar matter Stars: emission line, Be Stars: winds, outflows Supergiants |
| Summary: | The disc formation mechanism of B[e] supergiants is one of the puzzling phenomena in massive star evolution. Rapid stellar rotation seems to play an important role for the non-spherically symmetric mass-loss leading to a high-density disc- or ring-like structure of neutral material around these massive and luminous objects. The radial density and temperature structure as well as the kinematics within this high-density material are, however, not well studied. Based on the high-resolution optical spectra of a sample of B[e] supergiants in the Magellanic Clouds we especially searched for tracers of the kinematics within their discs. Besides the well-known [Oi] lines, we discovered the [Caii] λλ7291, 7324 lines which can be used as a complementary set of disc tracers. We find that these lines originate from very high density regions, located closer to the star than the [Oi] λ5577 line-forming region. The line profiles of both the [Oi] and the [Caii] lines indicate that the discs or rings of high-density material are in Keplerian rotation. We estimate plausible ranges of disc inclination angles for the sample of B[e] supergiants and suggest that the star LHA120-S22 might have a spiral arm rather than a disc. |
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