Beryllium abundance in turn-off stars of NGC 6752

Details Beryllium abundance in turn-off stars of NGC 6752 Beryllium abundance in turn-off stars of NGC 6752

2006-12-27

arxiv.org/abs/astro-ph/0612710v1

Astronomy and Astrophysics

Astrophysics

Accepted for publication by Astronomy & Astrophysics

Scientific paper

Aims: To measure the beryllium abundance in two TO stars of the Globular Cluster NGC 6752, one oxygen rich and sodium poor, the other presumably oxygen poor and sodium rich. Be abundances in these stars are used to put on firmer grounds the hypothesis of Be as cosmochronometer and to investigate the formation of Globular Clusters. Method:We present near UV spectra with resolution R$\sim 45000$ obtained with the UVES spectrograph on the 8.2m VLT Kueyen telescope, analysed with spectrum synthesis based on plane parallel LTE model atmospheres. Results:Be is detected in the O rich star with log(Be/H)=-12.04 $\pm$0.15, while Be is not detected in the other star for which we obtain the upper limit log(Be/H)$<$-12.2. A large difference in nitrogen abundance (1.6 dex) is found between the two stars. Conclusions:The Be measurement is compatible with what found in field stars with the same [Fe/H] and [O/H]. The 'Be age' of the cluster is found to be 13.3 Gyrs, in excellent agreement with the results from main sequence fitting and stellar evolution. The presence of Be confirms the results previously obtained for the cluster NGC 6397 and supports the hypothesis that Be can be used as a clock for the early formation of the Galaxy. Since only an upper limit is found for the star with low oxygen abundance, we cannot decide between competing scenarios of Globular Cluster formation, but we can exclude that 'polluted' stars are substantially younger than 'unpolluted' ones. We stress that the Be test might be the only measurement capable of distinguishing between these scenarios.

Affiliated with

Also associated with

No associations

Rating

Beryllium abundance in turn-off stars of NGC 6752 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 Beryllium abundance in turn-off stars of NGC 6752, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Beryllium abundance in turn-off stars of NGC 6752 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-334600