Rotation and activity in x-ray-selected late-type stars

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6465433

Takalo, L O

A spectroscopic study of 9 x-ray-selected late-type stars was conducted. These stars are x-ray bright (f/sub x/ > 3 x 10/sup -13/ ergs cm/sup -2/ s/sup -1/), serendipitously discovered EINSTEIN x-ray sources. They were selected from two large x-ray surveys: the Columbia Astrophysical Laboratory x-ray survey (5 stars) and the CFA Medium Sensitivity survey (MSS, 4 stars). Spectral classes for the stars were determined and radial and rotational velocities were measured. Four of the Columbia-survey stars (1E1818 + 3305, 1E1848 + 3325, 1E1919 + 0427 and 1E1937 + 3027) are found to be short-period binary systems (probable Rs CVn's). The fifth Columbia-survey star is found to be an active single G dwarf. None of the MSS survey stars are found to be binaries or to be optically active stars. The measured rotational velocities range from 10 to 60 km s/sup -1/, the faster rotators being the binary systems. Activity in the stars is studied by comparing the Balmer lines and the Ca II infrared triplet (IRT) lines to the inactive stars, and measuring the excess emission in these lines. All the Columbia-survey, stars are found to show excess emission in these lines. Also in all these stars this excess showed variability. The MSS survey stars do not show any measurable excess in these lines.

• Research Organization: Pennsylvania State Univ., University Park (USA)
• OSTI ID: 6465433
• 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
BALMER LINES
BINARY STARS
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DWARF STARS
MOTION
ROTATION
SPECTRA
STARS
SURVEYS
VELOCITY
X-RAY SPECTRA