WHAT ARE FS CMa STARS?
FS CMa stars is a subgroup of stars showing the B[e] phenomenon. The spectra of B[e] stars are characterised by
- forbidden emission lines
- infrared excess
- strong Balmer emission
- emission lines from the permitted transitions
The B[e] stars described first
Allen & Swings (1976).
The listed spectral properties show stars of different types and at different evolutionary stages.
Lamers et al. (1998) identified
the B[e] stars among Herbig Ae/Be stars, supergiants, symbiotic stars, and young planetary nebulae.
However, about the half of the B[e] stars known at that time remained unclassified. It was partially because
of the lack of good data, but there were stars that did not fit to any of these four groups.
Moreover, there were also stars whose spectra showed features of two or more of these four groups.
Miroshnichenko (2007) found that most of these
unclassified stars have similar properties and introduced a new group that he named FS CMa stars.
The definition of FS CMa stars (Miroshnichenko, 2007)
is not sufficiently sharp, i.e., stars of other types are in the
list .
