Abundance analysis of roAp stars: III. γ Equulei

Autor(en)

Tanya A. Ryabchikova, Saul J. Adelman, Werner Wolfgang Weiss, Rainer Kuschnig

Abstrakt

A spectroscopic analysis of the rapidly oscillating chemically peculiar star γEqu yields T eff = 7700 K, log g = 4.20, a microturbulence and υ · sin i which cannot be determined reliably, but which must be close to zero, because line broadening can be modelled by magnetic field effects alone. A mean magnetic field modulus of B = 4.0kG is estimated by comparing synthetic Zeeman pattern with observations. This value provides another phase point for magnetic field variations of γ Equ, a CP2 star with the longest hitherto known magnetic field period of about 77 years. For a simple dipolar field geometry, the angle between the line of sight and the magnetic axis ≈ 130deg (or ≈ 50 deg). We discuss in some detail the problems for abundance determinations in the presence of a strong magnetic field and we increase substantially the number of ions to 42, for which abundances are now available. In particular, we obtain a more reliable abundance of log(Eu/N tot) = -10.24, and find Fe and the light elements, C to Ca, to have nearly solar abundances. Co is clearly overabundant, and Nb and Mo are the most overabundant elements in γ Equ relative to the Sun.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Russian Academy of Sciences, College of Charleston

Journal

Astronomy & Astrophysics

Band

322

Seiten

234-241

Anzahl der Seiten

8

ISSN

0004-6361

Publikationsdatum

1997

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/abundance-analysis-of-roap-stars-iii--equulei(3bbf7de9-7697-43c0-a1e3-56caaecf73ee).html