NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
The intrinsic H I Lyman-alpha line profiles of late-type starsThe Lyman-alpha line of neutral hydrogen is probably the most important cooling channel for chromospheric plasma in late-type stars, yet it is also the least studied major line in the far ultraviolet. The scattering of much of the stellar Lyman-alpha flux by interstellar hydrogen, coupled with the geocoronal emission foreground, seriously complicates the analysis of the Lyman-alpha spectra. The influence of the local interstellar medium on the observed profiles was circumvented by observing stars with radial velocities sufficiently high to Doppler shift the center of the stellar emission line out of the interstellar absorption core. There are several stars that have high radial velocities by virtue of their presence in close binary systems. High resolution IUE (International Ultraviolet Explorer) spectra of Ly alpha line of two such eclipsing binary stars, AR Lac and TY Pyx, are obtained, at each orbital quadrature phase, when the projected orbital velocity is a maximum. By combining the spectra from opposite quadratures it is possible to piece together the entire stellar emission profiles. The third star in this study, delta Lep, is a single star with a high space velocity.
Document ID
19910008607
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Neff, J. E.
(NASA Goddard Space Flight Center Greenbelt, MD., United States)
Landsman, W. B.
(NASA Goddard Space Flight Center Greenbelt, MD., United States)
Bookbinder, J. A.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA., United States)
Linsky, J. L.
(Joint Inst. for Lab. Astrophysics Boulder, CO., United States)
Date Acquired
September 6, 2013
Publication Date
August 1, 1990
Publication Information
Publication: ESA, Evolution in Astrophysics: IUE Astronomy in the Era of New Space Missions
Subject Category
Astrophysics
Accession Number
91N17920
Funding Number(s)
CONTRACT_GRANT: NAG5-82
Distribution Limits
Public
Copyright
Other
Document Inquiry

Available Downloads

There are no available downloads for this record.
No Preview Available