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Simultaneous observations of CA II K and MG II K in T Tauri stars
Calvet, N.; Basri, G.; Imhoff, C. L.; Giampapa, M. S.
AA(Centro de Investigacion de Astronomia, Merida, Venezuela), AB(California, University, Berkeley, CA), AC(Computer Sciences Corp., Greenbelt, MD), AD(National Solar Observatory, Tucson, AZ)
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 293, June 15, 1985, p. 575-583. (ApJ Homepage)
Publication Date:
NASA/STI Keywords:
K Lines, Resonance Lines, Stellar Spectra, T Tauri Stars, Ultraviolet Astronomy, Calcium, Iue, Magnesium, Stellar Mass, Stellar Models
Bibliographic Code:


The first simultaneous, calibrated observations of the Ca II K and Mg II k resonance lines in T Tauri stars are presented. It is found that for T Tauri stars with mass greater than 1.5 solar mass, which have radiative cores and tend to be fast rotators, the k line seems to arise in an extended region (probably also responsible for the H-alpha emission), whereas the K line apparently originates closer to the highly inhomogeneous stellar surface. The lower mass stars, which are fully convective and tend to be slow rotators, are more easily described by a largely chromospheric model, consistent with main-sequence activity structures but at greater values of the nonradiative flux. The strongest emission-line stars in the low-mass group, however, are also likely to have extended k line regions.

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