Astronomy and Astrophysics – Astronomy
Scientific paper
Jan 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011aas...21712302p&link_type=abstract
American Astronomical Society, AAS Meeting #217, #123.02; Bulletin of the American Astronomical Society, Vol. 43, 2011
Astronomy and Astrophysics
Astronomy
Scientific paper
Contemporary models for the structure and evolution of rapidly-rotating OB stars predict a photospheric enrichment of nitrogen due to the mixing of the CNO-processed material from the star's core with the original surface material. The predicted N-enhancement increases as the star approaches its critical rotational velocity. Alternatively the Algol primaries should have N-enriched photospheres if the material currently being transferred is from the mass loser's original core. To test these predictions, the C and N abundances in selected early Be stars and B-type mass gainers in Algol systems have been determined from spectroscopic data obtained with the IUE and FUSE spacecraft. The abundance analyses, carried through with the Hubeny/Lanz NLTE codes TLUSTY/SYNSPEC, were confronted with some challenges that are not encountered in abundance studies of sharp-lined, non-emission B stars including the treatment of shallow, blended rotationally-broadened lines, the appropriate value for the microturbulence parameter, correction for disk emission and possible shell absorption, and latitudinal variation of Teff and log g. The FUV offers an advantage over the optical region as there is far less influence from disk emission and the N lines are intrinsically stronger. Particularly useful are the features of C II 1324 Å, C III 1176 Å, 1247 Å, N I 1243 Å, and N III 1183,84 Å. Be stars with v sin i < 150 km s-1 were chosen to minimize the effect of latitudinal parameter variation. Given the errors it appears that the N abundance in the Be stars is normal. Expected mixing is apparently suppressed, and this study lends no support for Be star models based upon critical rotation. However, expected N-enhancement and a low C abundance are inferred for the B-type primaries in some interacting binaries.
GJP is grateful for support from NASA Grants NNX07AH56G (ADP) and NNX07AF89G (FUSE), and the USC WiSE program.
No associations
LandOfFree
The Abundances of Carbon and Nitrogen in the Photospheres of Active B 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 The Abundances of Carbon and Nitrogen in the Photospheres of Active B Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Abundances of Carbon and Nitrogen in the Photospheres of Active B Stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1393692