First detection of dust clouds around R CrB variable stars
Abstract
From VLT/NACO diffraction-limited images of RY Sgr, we report the first direct detection of heterogeneities in the circumstellar envelope of a R Coronae Borealis variable star. Several bright and very large dust clouds are seen in various directions at several hundred stellar radii from RY Sgr, revealing high activity for the ejection of stellar material by R CrB variables. These observations do support the current interpretation that optically thick dust clouds are formed around the surface of this type of variable stars and, when passing between the star and the observer, produce the huge and sudden declines characterizing these objects in visible light. This is the first direct confirmation of a scenario proposed about 70 years ago.
Based on observations collected with the VLT/UT4 Yepun telescope (Paranal Observatory, ESO, Chile) using the NACO instrument (program ID 71.D-0543A).- Publication:
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Astronomy and Astrophysics
- Pub Date:
- December 2004
- DOI:
- 10.1051/0004-6361:200400095
- arXiv:
- arXiv:astro-ph/0411735
- Bibcode:
- 2004A&A...428L..13D
- Keywords:
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- stars: AGB and post-AGB;
- stars: variables: general;
- stars: individual: RY Sgr;
- stars: mass-loss;
- stars: circumstellar matter;
- techniques: high angular resolution;
- Astrophysics
- E-Print:
- Published in Astronomy and Astrophysics (A&