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CH CYGNI: Recent activity

Melvyn Taylor

CH Cygni is an unusual object, a triple system, in a class of so-called symbiotic stars, and in recent years has been in an overall decline phase from the autumn of 1994 when it was about magnitude 7.6.

A light-curve reproduced in BAA VSS circular no.90 1996 December shows the sectionís coverage of this remarkable variable since 1971. (see long-term lightcurve) The VSS light curve for 1996 is preliminary and shown below. The faintest magnitude this star reached as the plot shows was between 9.9 and 10.2 from June to November of 1996. The starís visible component faded rapidy from 1996 May at mag 9.4 to 10.1 in early July and this brought about an equally rapid development of the chartís comparison stars with the assistance of Brian Skiff.

During 1997 an initial investigation of VSS work shows CH Cygni to be slowly recovering possibly with semi-regular activity of a low amplitude. The star reached a mean magnitude of 9.0 in 1997 August, through to the end of 1997 at 9.1. There is large scatter in October and November with a few observers making estimates at the 8.5 magnitude level. It is possible these are discordant estimates in this interval. In 1998 though, up to April, the star appears to be going into a possible more active phase and observers are urged to go for this star whenever the sky clears in order to extend the light-curve.

This brief report of activity in CH Cygni is derived from the work of;-
Albrighton, Bone, Brundle, Day, Fraser, D.Gill, Hurst, Kelly, Livesey, Markham, Meacham, Middlemist, Poyner, Storey, Stott, Taylor, Toone, and Worraker.

The latest charts are 089.02 printed in the 1996 December circular and available on the chart page.


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