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Fri, 17 Jul 2015 - Chi Cygni : heading for a bright maximum

2014 was a disappointing year for observers of the variable star chi Cygni,... but 2015 is already much better!

Chi Cygni is a Mira type variable - a red giant star that varies over a large range in brightness due to pulsations in its outer layers. These brightness changes have a period of approx 407 days - about 13.5 months.

The 2014 peak in the brightness of chi Cygni occurred in late June and only reached about mag 6.4, making it one of the faintest ever. This compared rather unfavourably with the long term average peak brightness of mag 5.1.

Good news is that, on the way to its 2015 peak, chi Cygni has recently passed this average value, and the latest observations place it at around mag 4.6.

There is a good chance that it could yet brighten further. It is always difficult to predict the date on which chi Cygni will reach its peak, but the likelihood is that the 2015 peak will occur in either late July or early August. Hence it may still be a week or more away from its peak.

You can locate chi Cygni and follow the upcoming brightness changes using this finder chart.

Currently chi Cygni is between Eta Cygni and Fl 17 Cygni in brightness.

If you have a dark observing site, you should be able to spot chi Cygni with the naked eye as an 'extra' star in the 'neck' of Cygnus (the Swan). From less dark sites, however, you will need to use binoculars to easily identify it.

More information about chi Cygni can be found here

 

Added by: Tracie Heywood