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arXiv · 1602.00887

Carbon stars in the X-shooter Spectral Library

A. Gonneau·A. Lançon·S. C. Trager·B. Aringer·M. Lyubenova·W. Nowotny·R. F. Peletier·P. Prugniel·Y. -P. Chen·M. Dries·O. S. Choudhury·J. Falcón-Barroso·M. Koleva·S. Meneses-Goytia·P. Sánchez-Blázquez·A. Vazdekis
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Abstract

We provide a new collection of spectra of 35 carbon stars obtained with the ESO/VLT X-shooter instrument as part of the X-shooter Spectral Library project. The spectra extend from 0.3$\mu$m to 2.4$\mu$m with a resolving power above $\sim$ 8000. The sample contains stars with a broad range of (J-K) color and pulsation properties located in the Milky Way and the Magellanic Clouds. We show that the distribution of spectral properties of carbon stars at a given (J-K) color becomes bimodal (in our sample) when (J-K) is larger than about 1.5. We describe the two families of spectra that emerge, characterized by the presence or absence of the absorption feature at 1.53$\mu$m, generally associated with HCN and C$_2$H$_2$. This feature appears essentially only in large-amplitude variables, though not in all observations. Associated spectral signatures that we interpret as the result of veiling by circumstellar matter, indicate that the 1.53$\mu$m feature might point to episodes of dust production in carbon-rich Miras.

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A. Gonneau, A. Lançon, S. C. Trager, B. Aringer, M. Lyubenova, W. Nowotny, R. F. Peletier, P. Prugniel, Y. -P. Chen, M. Dries, O. S. Choudhury, J. Falcón-Barroso, M. Koleva, S. Meneses-Goytia, P. Sánchez-Blázquez, A. Vazdekis. 2016-02-02. Carbon stars in the X-shooter Spectral Library. https://doi.org/10.1051/0004-6361%2F201526292

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