Helium chemistry of ONC supergiants.

Details Helium chemistry of ONC supergiants. Helium chemistry of ONC supergiants.

Oct 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994a%26a...290..868s&link_type=abstract

Astronomy and Astrophysics 290, 868-874 (1994)

Astronomy and Astrophysics

Astrophysics

28

Stars: Abundances, Stars: Atmospheres, Stars: Evolution, Stars: Early-Type

Scientific paper

We present high-resolution, high signal-to-noise spectroscopic observations of the Galactic late-O supergiants HD154811 (OC9.7Iab), HD154368 (O9.5Iab), and HD123008 (ON9.5Iab). The spectra of these stars exemplify the carbon and nitrogen line-strength anomalies characteristic of the ONC supergiants. A hydrogen/helium non-LTE model-atmosphere analysis is carried out using extensive model atoms. Helium abundances (by number) of 0.09, 0.13, and 0.17 are obtained for the OC, normal O, and ON stars respectively. These results are consistent with Walborn's hypothesis that OC supergiants have a normal (i.e., cosmic) helium abundance whereas the morphologically-normal O supergiants and, to a greater extent, the ON supergiants exhibit the products of nucleosynthetic processing at their surfaces. We note that the diagnostic line HeIIλ4200 is probably contaminated by a NIII line in late-O supergiants.

Affiliated with

Also associated with

No associations

Rating

Helium chemistry of ONC supergiants. 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 Helium chemistry of ONC supergiants., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Helium chemistry of ONC supergiants. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1067611