Pulsation and Dust Chemistry in Galactic Carbon Stars (2023)

Undergraduate: Matthew O'Brien-Pifer

Faculty Advisor: Greg Sloan
Department: Physics and Astronomy

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Analysis of the archival infrared spectra from the Infrared Astronomical Satellite (IRAS) has revealed evidence of a potential population of unusual Galactic carbon stars. The details of their dust features are similar to metal-poor stars from the Small Magellanic Cloud, but are not expected in the Milky Way. Measuring the strength of the dust continuum with infrared colors and the strength of the SiC dust feature relative to the continuum reveals seven stars that consistently look like metal-poor stars which differ from typical Galactic carbon stars. Using data from Gaia and photometry from infrared surveys shows that the Galactic carbon stars follow the expected period magnitude trends. The trends of variable types are consistent with previous results from similar analyses of carbon stars from the Milky Way and the Magellanic Clouds. The dichotomy in the dust formation in semi-regular and Mira variables is less clear in the present sample than in previously studied samples, suggesting that further work is needed.

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