Chi Cygnus08

CHI CYGNI 2008 - 2009

NEWS:- CHI CYGNI REACHED MAXIMUM AT END OCTOBER AND IS NOW DECLINING TO IT'S QUIESCENT STATE.

Chi Cygni is a class of variable star known as a Long Period Variable or Mira-type after the prototype LPV, Omicron Ceti having the name Mira. The star is a red giant located approximately 300 light-years distant in the constellation of Cygnus. Every 408.5 days, the star puffs off its outer layers and in so doing, increases its luminosity/brightness. It then gradually fades back down below naked-eye visability towards magnitude +14. Predicted Maximum (outburst) was 12/11/2008 at +5.2 visual magnitude as per AAVSO.

Chi is now declining in brightness (+4.7 as observed by myself on the night of 06/12/2008) having attained maximum, visual magnitude of +3.9 as observed by myself on 31/08/2008. This does not quite match the brightness seen for Chi in 2006. Mostly, I observe this star with 10x50 binoculars. But when it fades to below magnitude +6, I will press my trusty scope (an 8" SCT ) into service to observe the star.

Below is a view of Chi Cygni taken by a webcam on the 10th August 2006.

Chi Cygnus details:
J2000.0 RA: 19h 50m 33.90s Dec: +32° 54' 51.0"
Other Names:
AAVSO 1946+32 BD+32 3593 HD 187796
HIP 97629 HR 7564 IRC +30395
RAFGL 2465 SAO 68943
Var. type M
Spec. type S6,2e-S10,4e(MSe)
Mag. range 3.3 - 14.2 V
Period 408.05d
Rise dur. 41%
Distance: ~300ly
2008 Predicted Average Minimum 1/6/2008 +13.4Mv
2008 Predicted Average Maximum 14/11/2008 +5.2Mv

This year I started monitoring the star in September when it was magnitude +8. As can be seen from the light curve below, there was a rapid rise to maxima. Now the star is fading albeit at a slower rate. The dates on the chart are those used by Variable-Star Astronomers, Julian days. More details of Julian dates and a Julian Date calculator visit American Association of Variable Star Observers (AAVSO)

Updated 9/1/2009