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X-rays from M-type Giants—Signs of Late Stellar Activity?

Published online by Cambridge University Press:  26 May 2016

Matthias Hünsch ,
Renada Konstantinova-Antova ,
Jürgen H. M. M. Schmitt ,
Klaus-Peter Schröder ,
Dimitar Kolev ,
Jose-Renan de Medeiros ,
Agnes Lèbre  and
Stephane Udry
Matthias Hünsch
Affiliation:
Institut für Theoretische Physik und Astrophysik, Univ. Kiel, 24098 Kiel, Germany
Renada Konstantinova-Antova
Affiliation:
Institute of Astronomy, Bulgarian Academy of Sciences, Sofia, Bulgaria
Jürgen H. M. M. Schmitt
Affiliation:
Hamburger Sternwarte, Univ. Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
Klaus-Peter Schröder
Affiliation:
Astronomy Centre, CPES, University of Sussex, Brighton, UK
Dimitar Kolev
Affiliation:
Institute of Astronomy, Bulgarian Academy of Sciences, Sofia, Bulgaria
Jose-Renan de Medeiros
Affiliation:
University Federal of Rio Grande do Norte, Natal, Brazil
Agnes Lèbre
Affiliation:
Groupe de Recherche en Astronomie et Astrophysique du Languedoc, Université Montpellier, France
Stephane Udry
Affiliation:
Observatoire de Genève, Switzerland

Abstract

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We present recent X-ray and optical observations of five M-type giants which were detected as strong X-ray sources. One of these stars, HR 5512, shows short-term variations in both X-ray flux as well as in the shape of the Hα and Ca ii H+K lines, and it rotates much faster than M-type giants usually do. No indication of binarity has been found for this star. We propose that the X-ray emission of HR 5512 is related to a large degree of stellar activity. For two other stars (15 Tri, HR 7547) radial velocity observations seem to indicate spectroscopic binarity.

Type
Part 5: Stellar Magnetic Activity and Evolution
Information
Symposium - International Astronomical Union , Volume 219: Stars as Suns : Activity, Evolution and Planets , 2004 , pp. 223 - 227
Copyright
Copyright © Astronomical Society of the Pacific 2004 

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