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Detection of Narrow C IV and Si IV Absorption Features in Spectra of Stars within 200 pc of The Sun

Published online by Cambridge University Press:  12 April 2016

P. Molaro
Affiliation:
Astronomical Observatory of Trieste, Italy I.S.A.S. Miramare, Trieste, Italy
J.E. Beckman
Affiliation:
Queen Mary College, London, England
M. Franco
Affiliation:
I.A.F.E., Buenos Aires, Argentina
C. Morossi
Affiliation:
Astronomical Observatory of Trieste, Italy
M. Ramella
Affiliation:
Astronomical Observatory of Trieste, Italy

Abstract

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Detection of narrow ( δλ< 0.5 A ) absorption features in C IV at λ λ 1548 and 1550 have been made in the spectra of 4 late B dwarfs within 200 pc of the sun; the Si IV doublet at λ λ 1393 and 1403 shows up in two of them. We argue that it is difficult to account for the strengths, widths, shapes , and C IV/Si IV ratios in terms consistent with a circumstellar origin except possibly for an asymmetric C IV component in one star (HD 135037). The most probable source is “semi-torrid” gas (cf. Bruhweiler et al. 1980) in the 50,000 K range forming the interfaces between cooler H I clouds and the ambient medium at coronal temperatures. Our technique, using late B rapid rotators, is useful for LISM probing of this kind.

Type
Hot Gas in the LISM: Optical, UV, and EUV Wavelengths
Copyright
Copyright © NASA 1984

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