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

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

¹ Armagh Observatory, Armagh BT61 9DG, N. Ireland
² University of Manchester, Jodrell Bank, Macclesfield, SK11 9DL, UK
³ Instituto de Astrofisica de Canarias, via Lactea, E-38200 La Laguna, Tenerife, Canary Islands, Spain
⁴ University of Thessaloniki, Department of Physics, Section of Astrophysics, Astronomy and Mechanics, GR-54006, Greece
⁵ School of Physics and Space Research, University of Birmingham, Birmingham B15 2TT, UK
⁶ Department of Astronomy, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802, U.S.A.
⁷ National Astronomical Observatory, Bulgarian Academy of Sciences, 72 Trakya Blvd., Sofia 1754, Bulgaria
⁸ LAEFF, Vilspa, Madrid, Spain

Send offprint request to: P.B. Byrne

Received: 28 April 1997
Accepted: 11 June 1997

Abstract

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.