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A&A Supplement series, Vol. 127, February I 1998, 505-519

Received April 28; accepted June 11, 1997

The photosphere and chromosphere of the RS Canum Venaticorum star, II Pegasi

II. A multi-wavelength campaign in August/September 1992

P.B. Byrnetex2html_wrap2035, H. Abdul Aziztex2html_wrap2037,gif, P.J. Amadotex2html_wrap2035, M.J. Arevalotex2html_wrap2041, S. Avgoloupistex2html_wrap2043, J.G. Doyletex2html_wrap2035, M.T. Eibetex2html_wrap2035, K.H. Elliotttex2html_wrap2049, R.D. Jeffriestex2html_wrap2049,gif, A.C. Lanzafametex2html_wrap2035,gif, C. Lazarotex2html_wrap2041, H.M. Murphytex2html_wrap2035, J.E. Nefftex2html_wrap2059, K.P. Panovtex2html_wrap2061, L.M. Sarrotex2html_wrap2063, J.H. Seiradakistex2html_wrap2043, and R.E. Spencertex2html_wrap2037

Send offprint request: P.B. Byrne

tex2html_wrap2069  Armagh Observatory, Armagh BT619DG, N.Ireland
tex2html_wrap2071  LAEFF, Vilspa, Madrid, Spain
tex2html_wrap2073  Department of Astronomy, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802, U.S.A.
tex2html_wrap2075  University of Thessaloniki, Department of Physics, Section of Astrophysics, Astronomy and Mechanics, GR-54006, Greece
tex2html_wrap2077  School of Physics and Space Research, University of Birmingham, Birmingham B15 2TT, UK
tex2html_wrap2079  University of Manchester, Jodrell Bank, Macclesfield, SK11 9DL, UK
tex2html_wrap2081  Instituto de Astrofisica de Canarias, via Lactea, E-38200 La Laguna, Tenerife, Canary Islands, Spain
tex2html_wrap2083  National Astronomical Observatory, Bulgarian Academy of Sciences, 72 Trakya Blvd., Sofia 1754, Bulgaria


We describe multi-wavelength, simultaneous observations of the RS CVn star, II Pegasi, most of which were obtained during the first three weeks of September 1992. These observations were made using optical and infra-red broad-band photometry, ultraviolet and optical spectroscopy and microwave monitoring. We have detected photospheric spots and chromospheric flares, as well as deriving a description of mean conditions in the quiet chromosphere. One of the flares, observed in optical photometry and ultraviolet spectroscopy is one of the most energetic ever observed on this star. We demonstrate that in its "quiescent'' state II Peg is continually variable in most of its chromospheric emissions, as well as in its coronal output.

keywords: stars: late-type; activity; chromosphere; II Peg -- radio continuum: stars

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