V391 Pegasi [SEP] constellation
V391 Pegasi
V391 Pegasi, also catalogued as HS 2201+2610, is a blue-white subdwarf star approximately 4,570 light-years away in the constellation of Pegasus. The star is classified as an "extreme horizontal branch star". It is small, with only half the mass and a bit less than one-quarter the diameter of the Sun. It has luminosity 15.4 times the Sun. It could be quite old, perhaps in excess of 10 Gyr. It is a pulsating variable star of the V361 Hydrae
phase, and eventually become asymptotic giant branch stars. The reason that some stars, like V391 Pegasi, lose so much mass is not well known.
Planetary system.
In 2007, a gas giant planet designated V391 Pegasi b was found in orbit by variable star timing method. This planet around an "extreme horizontal branch" star provided clues about what could happen to the planets in the Solar System when the Sun turns into a red giant within the next 5 billion years.