FG Sagittae
 |
FG Sagittae. Image: Keck Observatory
|
One of the most extraordinary variable stars known; a supergiant,
it lies in the constellation Sagitta at the
center of a young planetary nebula (He 1-5),
which it ejected a few thousand years ago, and has evolved significantly
within a human lifetime. Its spectral type
changed from B4Ia in 1955 to A5Ia in 1967 to F6Ia in 1972 and is currently
K2Ib. Its magnitude, which was 13 in 1900, brightened to 9 over the next
60 years, before fading again to 14 in 1992 and a deep minimum of 16 in
1996. Since the early 1990s, its variability has been like that of an R
Coronae Borealis star, dominated by dimming events and partial recoveries
most likely produced by obscurations of the star by dust. The consensus
view is that FG Sagittae is a final helium
flash object, similar to Sakurai's
Object, about to make a rapid transition to the white
dwarf stage.
Related categories
• NOTABLE
STARS
• VARIABLE
STARS
Also on this site:
Encyclopedia
of Alternative Energy & Sustainable Living
Encyclopedia
of History
BACK TO TOP
|
