Carbon stars in the X-Shooter Spectral Library
Abstract
We present a new collection of spectra of 35 carbon stars, obtained as part of the X-Shooter Spectral Library project. The sample contains stars with a broad range of (J-K) colours and pulsation properties, located in the Milky Way and the Magellanic Clouds. Two families of spectra emerge when (J-K) is larger than 1.6, characterised by the presence or absence of the absorption feature at 1.53 μm, generally associated with HCN and C_2H_2. We compare the observations with a new set of high-resolution synthetic spectra based on hydrostatic model atmospheres. The full spectrum fit of the observations to the grid of models allows us to identify the most likely atmospheric parameters. Those parameters, derived independently in the optical and near-infrared, are generally very consistent for (J-K) < 1.6. For the reddest stars showing the 1.53 μm feature, which are all large amplitude variables, the effects of pulsation are strong and the spectra are poorly matched with hydrostatic models. Dynamical models are needed to interpret those observations.
- Publication:
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Astronomical Society of India Conference Series
- Pub Date:
- 2017
- Bibcode:
- 2017ASInC..14...21G
- Keywords:
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- X-Shooter;
- carbon stars;
- atmospheres;
- spectrum fitting