Astronomy and Astrophysics – Astrophysics
Scientific paper
Aug 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993a%26a...275..463k&link_type=abstract
Astronomy and Astrophysics, Vol.275, NO.2/AUG(II), P. 463, 1993
Astronomy and Astrophysics
Astrophysics
7
Galaxy: Populations, Populations: Ipii, Ipii: Age, Discreteness
Scientific paper
From a magnitude limited survey of all A and F stars in the two high latitude areas SA 80 and 81 at b = 75°, intrinsic colors have been computed for about 160 F stars. The two areas contain a small sample of Strömgren's chemically defined intermediate population II stars (ipII). The age of this group of stars is determined from model isochrones adapted to the data in the (b - y)0-c0 and log Te-MV diagrams. From the recent oxygen enhanced isochrones, Bergbusch and VandenBerg 1992, the turn off age is derived to be as young as 6 Gyr and no color/Te or MV/log g shifts are required to obtain the turn off age. The mean metallicity of the ipII sample is [Fe/H] = -0.405±0.095. From a chemical and kinematical point of view, the intermediate population II stars may be part of the thick disk. The present 6 Gyr age estimate, derived from uvbyβ photometry of a magnitude complete polar sample, is thus ˜8 billion years younger than that derived from (B - V)0 turn off ages, mostly of kinematically selected samples, and found coeval to 47 Tue. The δm0-(b - y)0 or [Fe/H] - log Te diagrams and the δm1, δm0 histograms indicate that the polar intermediate population II stars may form a discrete chemical group among the cooler F stars and thus that ipII is not a metal weak tail to population I. The separation of pI and ipII metallicity is evident to the cool side of (b - y)0 ≍ 0.350. U and V LSR-velocities are computed for the SA 80 and SA 81 stars also included in the AGK3 Catalog and apparently the thick disk kinematics turn on already at [Fe/H] ≍ -0.2.
No associations
LandOfFree
On the Age and Chemical Discreteness of Stromgren's Intermediate Population-Ii 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 On the Age and Chemical Discreteness of Stromgren's Intermediate Population-Ii, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the Age and Chemical Discreteness of Stromgren's Intermediate Population-Ii will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1490091