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Probing the IRC+10 ° 216 circumstellar envelope using spectroscopic observations of background stars |
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| Authors: | Tim Kendall Nicolas Mauron June McCombie Peter Sarre |
| Affiliation: | 1. Observatório Astronómico de Lisboa, Tapada da Ajuda, Centro de Astronomia e Astrofísica da Universidade de Lisboa, 1349-018, Lisboa, Portugal 2. Groupe d’Astrophysique, CNRS, Université de Montpellier, Case 072, Place Bataillion, 34095, Montpellier Cedex 05, France 3. School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK |
| Abstract: | A unique and novel set of observations has been undertaken to study the circumstellar envelope (CSE) of the nearby (130 pc) carbon star IRC +10° 216 using optical absorption spectroscopy towards twobackground stars lying beyond the envelope.The primary aim of the observations is to search for diffuse band (DIB)carriers in the CSE. The circumstellar H+2H2column density expected along the line of sight towards the targets islarge compared to that derived from the small interstellar reddening inthis region, E B-V< 0.03 mag. We summarise our mainfindings, already reported in Kendall et al. (2002): The 6284Å DIB is detected in the VLT/UVES spectrum of one target, but clearly arises inthe foreground ISM. No other DIB is seen. Hence the DIB carriers, if present in the CSE, have a low abundance relative to H in the C-rich envelope of IRC +10°216, in comparison with this ratio in theISM. An important new result, previously unreported, concerns the detectionof circumstellar C2 via absorption of the Phillips bandnear 8760Å. |
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