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Paper: FS CMa Type Objects – Products of Intermediate-Mass Non-Conservative Evolution
Volume: 508, The B[e] Phenomenom: Forty Years of Studies
Page: 285
Authors: Miroshnichenko, A. S.
Abstract: The group of FS CMa type objects was formed nearly 10 years ago based on previously unclassified objects with the B[e] phenomenon. The main observational features of the group objects include strong emission-line spectra, typical of hot stars, and infrared excesses due to radiation of mostly hot circumstellar dust. Nearly one third of the group objects exhibit various signs of a cool stellar component that indicates a binary nature. The hot components have been shown to have nearly main sequence luminosities. However, mass loss rates that are much higher than those expected from single hot stars in this region of the Hertzsprung-Russell diagram are required to explain the observed emission-line strengths. Nevertheless, spectroscopic orbits have been determined only in two cases. The evolutionary state of the FS CMa objects is still not well constrained, although several possibilities, such as pre-main-sequence stars or proto-planetary nebulae, have been eliminated. I will review typical properties of the FS CMa objects and focus on a few well-studied examples. Possible evolutionary scenarios leading to the observed features will be discussed. Searching strategies for finding more group objects as well as their predecessor and successor objects will be outlined.
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