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Hot hb stars in globular clusters - physical parameters and consequences for theory. vi. the second parameter pair m3 and m13
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Moehler, S. Landsman, W. B. Grundahl, F. Sweigart, A. V. |
| Copyright Year | 2002 |
| Description | We present the results of spectroscopic analyses of hot horizontal branch (HB) stars in M13 and M3, which form a famous second parameter pair. From the spectra we derived - for the first time in M13 - atmospheric parameters (effective temperature and surface gravity) as well as abundances of helium, magnesium, and iron. Consistent with analyses of hot HB stars in other globular clusters we find evidence for helium depletion and iron enrichment in stars hotter than about 12,000 K in both M3 and M13. Accounting for the iron enrichment substantially improves the agreement with canonical evolutionary models, although the derived gravities and masses are still somewhat too low. This remaining discrepancy may be an indication that scaled-solar metal-rich model atmospheres do not adequately represent the highly non-solar abundance ratios found in blue HB stars with radiative levitation. We discuss the effects of an enhancement in the envelope helium abundance on the atmospheric parameters of the blue HB stars, as might be caused by deep mixing on the red giant branch or primordial pollution from an earlier generation of intermediate mass asymptotic giant branch stars. |
| File Size | 1179733 |
| Page Count | 13 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20030032938 |
| Archival Resource Key | ark:/13960/t3616082n |
| Language | English |
| Publisher Date | 2002-01-01 |
| Access Restriction | Open |
| Subject Keyword | Astronomy Stellar Spectra Stellar Atmospheres Stellar Temperature Hot Stars Spectroscopic Analysis Iron Magnesium Globular Clusters Helium Horizontal Branch Stars Stellar Models Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
