Spectra of Type II Cepheid Candidates and Related Stars

We present low-resolution spectra for variable stars in the Cepheid period range from the ROTSE-I Demonstration Project and the All Sky Automated Survey, some of which were previously identified as type II Cepheid candidates. We have derived effective temperatures, gravities, and metallicities from...

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Bibliographic Details
Published in:The Astronomical journal 2011-02, Vol.141 (2), p.53-jQuery1323898276551='48'
Main Authors: Schmidt, E. G, Rogalla, Danielle, Thacker-Lynn, Lauren
Format: Article
Language:English
Subjects:
AMPLITUDES
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CEPHEIDS
GRAVITATION
MAIN SEQUENCE STARS
PULSATING VARIABLE STARS
SPECTRA
STARS
STELLAR ACTIVITY
VARIABLE STARS
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Summary:We present low-resolution spectra for variable stars in the Cepheid period range from the ROTSE-I Demonstration Project and the All Sky Automated Survey, some of which were previously identified as type II Cepheid candidates. We have derived effective temperatures, gravities, and metallicities from the spectra. Based on this, three types of variables were identified: Cepheid strip stars, cool stars that lie along the red subgiant and giant branch, and cool main-sequence stars. Many fewer type II Cepheids were found than expected and most have amplitudes less than 0.4 mag. The cool variables include many likely binaries as well as intrinsic variables. Variation among the main-sequence stars is likely to be mostly due to binarity or stellar activity.
ISSN:1538-3881
0004-6256
1538-3881
DOI:10.1088/0004-6256/141/2/53