Multifrequency observations of the eclipsing symbiotic triple system CH Cyg during the 1992--94 active phase

A. Skopal, M. F. Bode, Myfanwy Bryce, D. Chochol, R. J. Davis, L. Errico, S. P. S. Eyres, L. Hric, R. J. Ivison, H.t. Kenny, R. Komzik, J. Meaburn, S. Tamura, Z. Urban, A. A. Vittone, A. Evans, A. R. Taylor

Research output: Contribution to journalArticlepeer-review


The authors present UBV photoelectric photometry, plus optical and ultraviolet low- and high-resolution spectroscopy and MERLIN, VLA and JCMT radio/mm-wave observations of the symbiotic star CH Cyg during the period 1989.7-1995.5 which covers the 1992 outburst. On 1990 July 22 the spectrum displayed only absorption features characterized by broad hydrogen profiles, indicating that CH Cyg underwent a dramatic transient change, losing its circumstellar shell. In early 1992 the star's brightness increased by about 2.5 mag in the U band, and then gradually increased from U ≡ 8.5 at that time to U ≡ 6.7 in mid-1994. In 1992 September - November and 1994 October - December, the two deep minima caused by an eclipse of the active component by the cool component in the symbiotic pair of the triple CH Cyg system were observed. A decrease of the star's brightness to U ≡ 11 in mid-1995 indicates that this active phase is over. During the outburst the energy distribution of the hot component exhibits two maxima: the first in the far-UV (1500-1900 Å) region, and the second one around the U band. Evolution of the spectrum and variation in the hydrogen line profiles result from an irregular, high-velocity and in part bipolar outflow from the central star. Radio observations indicate a radio flux increase and suggest an expansion of the outer radius of the wind material around the active component.
Original languageEnglish
Pages (from-to)327-346
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 11 Sept 1996


  • line: profiles
  • binaries: symbiotic
  • stars: individual: CH Cyg
  • stars: mass-loss
  • radio continuum: stars
  • ultraviolet: stars
  • symbiotic stars: light curves
  • symbiotic stars: spectra


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