The many faces of F stars - A rotational modulation study of Capella, Procyon, and Caph with the International Ultraviolet Explorer

Journal Article · Mon Jul 01 00:00:00 EDT 1991 · Astrophysical Journal; (United States)

DOI:https://doi.org/10.1086/170236· OSTI ID:5318711

Ayres, T R ^[1]

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1. Colorado, University, Boulder (USA)

Far-UV spectroscopy of the F stars Capella, Procyon, and Caph is reported. Although all three stars are regard as chromospherically 'active', none exhibited any sensible rotational modulations, indicating a smooth surface distribution of chromospheric emission. Balancing this nonsolar behavior are a variety of puzzling differences among the three stars. On the one hand, the C IV features of Procyon are narrow, while that of the Capella secondary and Caph are broad; differences in v sin i alone cannot explain the dichotomy. On the other hand, the high-excitation emissions of the Capella secondary and Procyon, but not Caph, exhibit statistically significant redshifts. The significance of these results is discussed in the light of the speculation by Simon and Drake (1989) that the X-ray deficient coronae of the early F dwarfs are produced by classical acoustic heating. 55 refs.

• OSTI ID: 5318711
• Journal Information: Astrophysical Journal; (United States), Vol. 375; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
STARS
ULTRAVIOLET SPECTRA
EMISSION SPECTRA
FAR ULTRAVIOLET RADIATION
HEATING
ROTATION
STELLAR ACTIVITY
STELLAR CHROMOSPHERES
X RADIATION
ATMOSPHERES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
MOTION
RADIATIONS
SPECTRA
STELLAR ATMOSPHERES
ULTRAVIOLET RADIATION
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources