Astronomy and Astrophysics – Astrophysics
Scientific paper
1998-11-20
Astronomy and Astrophysics
Astrophysics
8 pages, 13 postscript figures, 6 postscript tables To be published on Astronomy & Astrophysics Supplement Series
Scientific paper
10.1051/aas:1999126
We use evolutionary calculations presented in a recent paper (Cassisi et al. 1998) to predict B,V,I magnitudes for stars in galactic globulars. The effect of the adopted mixing length on stellar magnitudes and colors is discussed, showing that the uncertainty on such a theoretical parameter prevents the use of MS stars as bona fide theoretical standard candles. However, comparison with Hipparcos data for field subdwarfs discloses a substantial agreement between theory and observation. Present predictions concerning the magnitude of TO and of HB stars are compared with similar results appeared in the recent literature. We present and discuss a theoretical calibration of the difference in magnitude between HB and TO as evaluated with or without element sedimentation. Finally we use theoretical HB magnitudes to best fit the CM diagram of M68 and M5, taken as representative of metal poor and intermediate metallicity galactic globulars, deriving an age of 11$\pm$1.0 Gyr and 10$\pm$1.0 Gyr, respectively, for the adopted chemical compositions, plus an additional uncertainty of $\pm$1.4 Gyr if the uncertainty on the chemical composition is taken into account. This result is discussed on the basis of current evaluations concerning cluster ages and distance moduli.
Cassisi Santi
Castellani Vittorio
Degl'Innocenti Scilla
Salaris Maurizio
Weiss Alexander
No associations
LandOfFree
Galactic Globular Cluster Stars: from Theory to Observation 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 Galactic Globular Cluster Stars: from Theory to Observation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Galactic Globular Cluster Stars: from Theory to Observation will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-634534