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IR Spectroscopy of Stars Over Different Instability Strips

Presentation #337.04 in the session Pulsating Variable Stars.

Published onJul 01, 2023
IR Spectroscopy of Stars Over Different Instability Strips

Using the TripleSpec camera system on the 3.5-m of the Astrophysical Research Consortium (ARC) located at the Apache Point Observatory in New Mexico, we have begun a program to obtain spectra of pulsating variable stars over a number of instability strips. This includes the traditional instability strip with Cepheids, RR Lyrae, and delta Scuti variables. Also, the nearby gamma Doradus stars. Finally, the hotter beta Cephei stars. The TripleSpec camera system provides coverage from about 0.95 microns to 2.45 microns, with the normal atmospheric gaps.

Within the overall spectra we find 3 prominent lines from the Hydrogen Paschen sequence P-beta, P-gamma and P-delta. Further to the red we find 7-10 Hydrogren Brackett lines starting with the gamma line. The number of lines seen is dependent on the temperature of the object. We plan to obtain a magnitude limited sample for each group for targets reachable by the ARC telescope. This will provide 1-3 observations per target. However, the observations will not be targeted to specific phase points. Beyond an examination of the atmospheric conditions for these stars, these observations will be used to search for faint red companions. We have found a number of examples with CO band heads, showing a cool companion. For a smaller sample of targets we have obtained observations that fully sample the phased light curve.

We will present preliminary results from all aspects of this program. This will include targets with newly found companions and a discussion of atmospheric conditions. Once data from this program are published the individual spectra will be make available for download.

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