NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Physical Parameters of Hot Horizontal-Branch Stars in NGC 6752: Deep Mixing and Radiative LevitationAtmospheric parameters (T(sub eff), log g and log n(sub He)/n(sub H-dot)) are derived for 42 hot horizontal branch (HB) stars in the globular cluster NGC 6752. For 19 stars Mg II and Fe II lines are detected indicating an iron enrichment by a factor 50 on average with respect to the cluster abundance whereas the magnesium abundances are consistent with the cluster metallicity. This finding adds to the growing evidence that radiative levitation plays a significant role in determining the physical parameters of blue HB stars. Indeed, we find that iron enrichment can explain part, but not all, of the problem of anomalously low gravities along the blue HB. Thus the physical parameters of horizontal branch stars hotter than about 11,500 K in NGC 6752, as derived in this paper, are best explained by a combination of helium mixing and radiative levitation effects.
Document ID
19990079396
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Moehler, S.
(Astronomisches Inst. Bonn, Germany)
Sweigart, A. V.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Landsman, W. B.
(Raytheon Co. Greenbelt, MD United States)
Heber, U.
(Astronomisches Inst. Bonn, Germany)
Catelan, M.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
August 19, 2013
Publication Date
April 19, 1999
Publication Information
Publication: Astronomy and Astrophysics
Subject Category
Astrophysics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

There are no available downloads for this record.
No Preview Available