Analysis of the circumstellar environment of the B[ e] star HD 45677 (FS Canis Majoris)

Aims.We studied the circumstellar environment of the B[ e] star HD 45677 through the analysis of the emission lines from ionized metals.
Methods: .We used the statistical approach of the self absorption curve method (SAC) to derive physical parameters of the line emitting region.
Results: .The Fe II and Cr II double-peaked emission line structure is explained by the presence of a thin absorption component red shifted by ~3 km s^-1. This absorption component can be interpreted geometricaly as being due to infalling material perpendicularly to the disk seen nearly pole-on, as indicated by the emission line structure. The Cr II and Fe II emission lines have a complex structure with two (narrow and broad) components, of 45 and 180 km s^-1 FWHM for the permitted lines and 25 and 100 km s^-1 FWHM for the forbidden ones, respectively. From our best data set of 1999, we obtained a Boltzmann-type population law whose excitation temperature is 3900_-600⁺⁹⁰⁰ K and 3150_-300⁺³⁵⁰ K for the narrow component lower and upper levels respectively. We obtained an excitation temperature of 3400_-300⁺³⁵⁰ K for the broad component upper levels. The forbidden lines are found to be formed in the outer regions with higher excitation temperatures of 10 500 ± 1000 K and 8000 ± 1500 K for the narrow and broad components respectively in 1999. Our results are consistent with line formation in a rotating disk, around a young star. In the framework of a very simplified geometrical model, we argue that the narrow components are principaly emitted by an optically thin disk seen nearly pole-on, in a region whose minimum radius is estimated to be 4×10¹² cm, while the broad ones are formed in a disk-linked wind.