Nebula around R Corona Borealis
Abstract
The star R Corona Borealis (R CrB) shows forbidden lines of [O II], [N II], and [S II] during the deep minimum when the star is fainter by about 8 to 9 magnitudes from normal brightness, suggesting the presence of nebular material around it. We present low and high spectral resolution observations of these lines during the ongoing deep minimum of R CrB, which started in July 2007. These emission lines show double peaks with a separation of about 170 km/s. The line ratios of [S II] and [O II] suggest an electron density of about 100 cm$^{-3}$. We discuss the physical conditions and possible origins of this low density gas. These forbidden lines have also been seen in other R Coronae Borealis stars during their deep light minima and this is a general characteristic of these stars, which might have some relevance to their origins.
- Publication:
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arXiv e-prints
- Pub Date:
- December 2011
- DOI:
- 10.48550/arXiv.1112.6225
- arXiv:
- arXiv:1112.6225
- Bibcode:
- 2011arXiv1112.6225K
- Keywords:
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- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Proceedings IAU Symposium No.283, 2011 ` Planetary Nebulae: an Eye to the Future'