Astronomy and Astrophysics – Astrophysics
Scientific paper
Jul 1999
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999ap%26ss.265..153k&link_type=abstract
Astrophysics and Space Science, v. 265, Issue 1/4, p. 153-156 (1999).
Astronomy and Astrophysics
Astrophysics
2
Scientific paper
Low metallicity (-3 <=[Fe/H] < = -1) halo field giants exhibit the expected correlation of Na and Mg abundances, based on the assumption that Na is produced in the same nucleosynthetic sites as are the alpha elements, confirming a result noted by Sneden (1998). On the other hand, giants in at least some globular clusters (especially M13, but also M15 and NGC 6752) do not exhibit the Mg vs Na correlation found among halo field giants (Hanson et al., 1998). The very large [Na/Fe]-ratios and widely scattered [Mg/Fe]-ratios found among M13 giants depend, on the average, on evolutionary state and are probably induced by deep mixing of stellar envelopes through the CNO hydrogen-burning shell. Why M13 (and M15 and NGC 6752) giants should experience deep mixing whereas field halo giants in the same evolutionary state mix not at all is an anomaly unexplained by current theories of stellar evolution. By contrast, giants in the outer halo cluster NGC 7006 show little evidence of deep mixing (Kraft et al., 1998). These differences in the degree of deep mixing among stars in related, but different, stellar populations may be connected to the so-called `second parameter effect'.
No associations
LandOfFree
Composition Differences Between Globular Cluster and Halo Field Giants 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 Composition Differences Between Globular Cluster and Halo Field Giants, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composition Differences Between Globular Cluster and Halo Field Giants will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1618847