X-ray observations of stellar coronae

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1980

OSTI ID:5545589

Topka, K P

The Einstein X-Ray Observatory (HEAO-2) has been used to search for X-ray emission from a wide variety of stars in our galaxy. A significant fraction of the data was obtained via the 8.5 magnitude stellar survey, which is reported here. This survey searches for X-ray emission from all stars brighter than visual magnitude 8.5 that serendipitously fell into the Imaging Proportional Counter field-of-view of the Einstein Observatory. The survey includes 227 separate fields that contain a total of 276 stars with V < 8.5. A wide range of spectral types and luminosity classes are represented. X-Ray emission in excess of 3-sigma above local background was discovered from 33 stars; 3-sigma upper limits have been determined for the remaining 243 stars. Comparison of X-ray source detection statistics with the expected frequency of stars brighter than V = 8.5 as a function of spectral type and luminosity class shows that the present visual magnitude limited survey can define the X-ray luminosity for dwarf F stars and provides constraints for the high luminosity tails of the X-ray luminosity functions for other types of stars constructed from other Einstein observations. The results of the 8.5 and Gliese survey have been integrated with those of four othe Einstein surveys. In total, X-ray emission has been detected from 156 stars, with most of these representing initial discoveries. Most of the observations can be explained by the presence of hot coronae around stars of nearly every spectral type. The consequences of these observations in terms of the presence of stellar outer convection zones, surface magnetic fields, and rotation rates are discussed.

• Research Organization: Harvard Univ., Boston, MA (USA)
• OSTI ID: 5545589
• Country of Publication: United States
• Language: English

Related Subjects

640102 -- Astrophysics &amp; Cosmology-- Stars &amp; Quasi-Stellar
Radio &amp; X-Ray Sources
640103* -- Astrophysics &amp; Cosmology-- Quasi-Stellar
Radio
&amp; X-Ray Sources-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CONVECTION
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
LIMITING VALUES
LUMINOSITY
MAGNETIC FIELDS
MOTION
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
ROTATION
SATELLITES
STARS
STELLAR ATMOSPHERES
X RADIATION