Astronomy and Astrophysics – Astrophysics
Scientific paper
Jun 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993a%26a...273..212d&link_type=abstract
Astronomy and Astrophysics, Vol.273, NO. 1/JUNI, P. 212, 1993
Astronomy and Astrophysics
Astrophysics
29
Stars: Abundances, Stars: Subdwarfs, Stars: Fundamental Parameters, Stars: Evolution
Scientific paper
The NLTE analyses of four extremely helium rich sdO stars based on high resolution, high S/N CASPEC spectra are presented. Effective temperatures, gravities and the abundances of H, He, C, N, O, Ne, Mg, and Si have been deter- mined. It is found that LSIV+1O°9, LSS 1274, and UV 0832-01 have very similar parameters: Teff = 44500±1000 K, log g = 5.55±0.15. H is undetected in all programme stars resulting in a upper limit of nH/nHe ≤ 0.1. C, N, and Ne are enriched, while Mg and Si are solar and O is slightly depleted. Microturbulent velocity is found to be lower than to km/s. The positions of these stars in the (log Teff,log g) diagram indicate, that they are post-EHB (Extended Horizontal Branch) stars. Their atmospheric composition can be understood as a mixture of CNO and 3 - α processed material. UV 0904-02 is slightly hotter, Teff = 46500±1000 K, log g = 5.55±0.15, and is as well a post-EHB star. The atmosphere also displays a mixture of CNO and 3-α processed material, the primordial metallicity however, was possibly lower.
No associations
LandOfFree
Spectral Analysis of Extremely Helium Rich Subdwarf O-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 Spectral Analysis of Extremely Helium Rich Subdwarf O-Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spectral Analysis of Extremely Helium Rich Subdwarf O-Stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1732612