Behaviour of the HeI 587.6, 667.8, 706.5 and 728.1nm lines in B-type stars. On the helium stratification in the atmosphere of magnetic helium peculiar stars.

Details Behaviour of the HeI 587.6, 667.8, 706.5 and 728.1nm lines in B-type stars. On the helium stratification in the atmosphere of magnetic helium peculiar stars. Behaviour of the HeI 587.6, 667.8, 706.5 and 728.1nm lines in B-type stars. On the helium stratification in the atmosphere of magnetic helium peculiar stars.

Apr 1997

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997a%26a...320..893l&link_type=abstract

Astronomy and Astrophysics, v.320, p.893-898

Astronomy and Astrophysics

Astrophysics

12

Diffusion, Line: Formation, Stars: Abundances, Stars: Chemically Peculiar, Stars: Early-Type

Scientific paper

High resolution spectra of the HeI587.6, 667.8 706.5 and 728.1nm lines have been obtained to test the prediction (notably by Vauclair et al. 1991) that helium abundance should decrease with depth in helium rich stars and increase in helium weak stars. A sample of B-type main sequence stars, with expected solar abundances and non stratified atmospheres, have also been observed in order to compare the behaviour of the selected lines with the chemically peculiar case and with theory. We found significant discrepancies with theory for the lines HeI 706.5. and 728.1nm, and, in order to outline differences between 'normal' and 'peculiar' stars, we have adopted an empirical correction to the Lorentz broadening parameter in the Voigt profile, under the assumption of LTE. This parameter is derived from the imposition of a satisfactory fit with observations for the relation equivalent width vs. effective temperature for normal B stars. For helium rich stars we confirm Vauclair et al. (1991) predictions that helium abundance decreases with depth. However, we found that helium abundance decreases with depth in helium weak stars too, which contradicts Vauclair et al. (1991) predictions. For some peculiar stars, the inferred helium abundance is in disagreement with the peculiarity class reported in the General Catalogue of Ap and Am stars (Renson et al. 1991).

Affiliated with

Also associated with

No associations

Rating

Behaviour of the HeI 587.6, 667.8, 706.5 and 728.1nm lines in B-type stars. On the helium stratification in the atmosphere of magnetic helium peculiar stars. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Behaviour of the HeI 587.6, 667.8, 706.5 and 728.1nm lines in B-type stars. On the helium stratification in the atmosphere of magnetic helium peculiar stars., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Behaviour of the HeI 587.6, 667.8, 706.5 and 728.1nm lines in B-type stars. On the helium stratification in the atmosphere of magnetic helium peculiar stars. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1315692