Detection of soft X-rays from. cap alpha. Lyrae and eta Bootis with an imaging X-ray telescope

Journal Article · Sun Apr 15 04:00:00 EST 1979 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/157000· OSTI ID:6154944

Topka, K; Fabricant, D; Harnden, Jr, F R; Gorenstein, P; Rosner, R

Two nearby stars have been detected in the soft X-ray band with an imaging X-ray telescope flown aboard two sounding rockets. The exposure times were 4.8 and 4.5 s for the images of the AO V star ..cap alpha.. Lyrae (Vega) and the GO IV star eta Bootis, respectively. Laboratory measurements rule out the possibility that the observed signals were due to UV contamination. These X-ray observations imply luminosities of L/sub X/(0.2--0.8 keV) approx. =3 x 10/sup 28/ ergs s/sup -1/ for Vega and L/sub X/(0.15--1.5 keV) approx. =1 x 10/sup 29/ ergs s/sup -1/ for eta Boo. A coronal interpretation of the X-rays from Vega is in serious conflict with simple convective models for early-type main-sequence stars. Magnetic field activity may be responsible for heating the corona, as has been suggested for the Sun. In the case of eta Boo, a coronal interpretation is also favored; however, if the unseen companion of eta Boo is degenerate, the X-ray emission may instead originate in a stellar wind accreting upon a white dwarf or neutron star.

• Research Organization: Harvard-Smithsonian Center for Astrophysics
• OSTI ID: 6154944
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 229:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640103* -- Astrophysics & Cosmology-- Quasi-Stellar
Radio
& X-Ray Sources-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DWARF STARS
LUMINOSITY
MAGNETIC FIELDS
MAIN SEQUENCE STARS
NEUTRON STARS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SPECTRA
STARS
STELLAR ATMOSPHERES
STELLAR WINDS
WHITE DWARF STARS
X-RAY SPECTRA