Properties and origin of FS CMa stars

Key words: stars, stellar evolution, FS CMa stars, B[e] stars, mergers, spectroscopy, polarimetry, photometry, N-body simulations, MHD simulations

FS CMa stars are stars showing the B[e] phenomenon, i.e., the presence of forbidden emission lines and infrared excess in their spectra. Both characteristics indicate the existence of an extended gaseous and dusty circumstellar region. The origin and evolutionary status of these stars remain uncertain. The widely accepted scenario is a binarity. However, a post-merger has recently been discovered among FS CMa stars (IRAS 17449+2320, Korčáková et al. 2022). It is very likely that more post-mergers are hidden within this group. Moreover, the evolutionary sequence of mergers may be traced within FS CMa group.

Our working group focuses on the study of FS CMa stars using spectroscopy, polarimetry, N-body simulations, magneto-hydrodynamic simulations, and photometry. The detailed program of the PhD study will be created based on student's preferences and may also cover other related fields, such as imaging, radio observations, or stellar evolution.

The importance of the work lies not only in the discovery of new stellar mergers, but the main goal is to fill the gaps in our understanding of the stellar evolution. For example, IRAS 17449+2320 is very likely a progenitor of Ap stars, an object that has been sought after for decades.

For more details about FS CMa stars and our research, please, see https://sirrah.troja.mff.cuni.cz/~kor/FS_CMa.html

References:

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[7] Zickgraf, F.J., Wolf, B., Stahl, O., Leitherer, C., & Klare, G. A&A, 143, 421