Observations of coronal x-ray sources and an analysis of the stellar contribution to the soft x-ray background

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5228822

Caillault, J P

To establish the prevalence of x-ray emission among field stars, a systematic search was conducted of over 1700 stars brighter than 10th magnitude observed by the Einstein Observatory. Fewer than 4% of the stars were detected at a limiting flux value of approx.10/sup -13/ ergs cm/sup -2/s/sup -1/. The observed distribution of x-ray to optical flux ratios was used for both the detected and undetected stars to limit the x-ray luminosity function for field stars of all spectral types. The author also conducted an extensive soft x-ray survey of the Pleiades open cluster. The most-luminous G-stars require a substantially different coronal structure than that found on the Sun; a larger scale length for coronal loops may be partially responsible for these high luminosities. The lack of rotational modulation of the emission from most of the late type stars requires the presence of numerous active regions distributed more uniformly than is the case in the solar corona. A lack of correlation of L/sub x/ with V/sub eq/ for a homogeneous sample of K dwarfs, coupled with their high mean luminosity, argues for the importance of at least one parameter besides rotation in setting the x-ray luminosity of (at least) young late type stars. A map of the soft x-ray emission along a galactic meridian within +/-3/sup 0/ of the galactic plane is presented.

• Research Organization: Columbia Univ., New York (USA)
• OSTI ID: 5228822
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BACKGROUND RADIATION
ELECTROMAGNETIC RADIATION
EQUIPMENT
IONIZING RADIATIONS
LUMINOSITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATION SOURCES
RADIATIONS
SOFT X RADIATION
STAR CLUSTERS
STELLAR ATMOSPHERES
STELLAR CORONAE
X RADIATION
X-RAY EQUIPMENT
X-RAY SOURCES