1997A&A...327.1137R -
Astronomy and Astrophysics, volume 327, 1137-1146 (1997/11-3)
Abundance analysis of roAp stars. IV. HD 24712.
RYABCHIKOVA T.A., LANDSTREET J.D., GELBMANN M.J., BOLGOVA G.T., TSYMBAL V.V. and WEISS W.W.
Abstract (from CDS):
We present the first abundance analysis of the rapidly oscillating chemically peculiar star HD 24712, and determine a Teff=7250K, logg=4.3, and ξt=1km/s. Microturbulence seems to be entirely simulated by a magnetic field with a polar field strength of 4.4kG and of dipolar structure, both of which are supported by our polarimetric observations. Rotation of HD 24712 and a spotty surface distribution of the elements result in different mean abundances for different (magnetic) phases. Our results do not support the hypothesis of a monotonic correlation between the amplitude of abundance variations and the atomic number Z, and we present arguments in favour of one of the rotation periods (Prot=12.4610)d discussed in the literature. Rare earth elements are the most overabundant elements relative to the sun, and they have the largest abundance amplitude during a rotation cycle; only Mg has a larger amplitude. For HD 24712 we find a clear overabundance of Co while most of the other iron peak elements are underabundant. A comparison of the abundance pattern with the other three roAp stars analyzed so far by us concludes the paper. A systematic difference between surface gravities obtained from spectroscopy and from both asteroseismology and evolutionary tracks is found for the roAp stars HD 24712, α Cir and γ Equ.
Abstract Copyright:
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Journal keyword(s):
stars: abundances - chemically peculiar - magnetic field - oscillations - pulsations - individual: HD 24712
Simbad objects:
5
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