O/Fe in metal-poor main sequence and subgiant stars

Astronomy and Astrophysics – Astrophysics

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

ps file, 18 pages (including 10 figures) - Accepted for publication in A&A

Scientific paper

10.1051/0004-6361:20020736

A study of the O/Fe ratio in metal-poor main sequence and subgiant stars is presented using the [OI] 6300A line, the OI 7774A triplet, and a selection of weak FeII lines observed on high-resolution spectra acquired with the VLT UVES spectrograph. The [OI] line is detected in the spectra of 18 stars with -0.5 < [Fe/H] < -2.4, and the triplet is observed for 15 stars with [Fe/H] ranging from -1.0 to -2.7. The abundance analysis was made first using standard model atmospheres taking into account non-LTE effects on the triplet: the [OI] line and the triplet give consistent results with [O/Fe] increasing quasi-linearly with decreasing [Fe/H] reaching [O/Fe] ~ +0.7 at [Fe/H] = -2.5. When hydrodynamical model atmospheres representing stellar granulation in dwarf and subgiant stars replace standard models, the [O/Fe] from the [OI] and FeII lines is decreased by an amount which increases with decreasing [Fe/H]. The [O/Fe] vs [Fe/H] relation remains quasi-linear extending to [O/Fe] ~ +0.5 at [Fe/H] = -2.5, but with a tendency of a plateau with [O/Fe] ~ +0.3 for -2.0 < [Fe/H] < -1.0, and a hint of cosmic scatter in [O/Fe] at [Fe/H] ~ -1.0. Use of the hydrodynamical models disturbs the broad agreement between the oxygen abundances from the [OI], OI, and OH lines, but 3D non-LTE effects may serve to erase these differences.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

O/Fe in metal-poor main sequence and subgiant 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 O/Fe in metal-poor main sequence and subgiant stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and O/Fe in metal-poor main sequence and subgiant stars will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-32218

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.