V391 Pegasi

Starbox begin
name = V391 Pegasi Starbox observe
epoch = J2000.0
constell = Pegasus
ra = RA|22|04|12.2
dec = DEC|+26|25|08
appmag_v = +14.57 Starbox character
class = sdB
variable = EC 14026 Starbox astrometry
dist_ly = 4570
dist_pc = 1400
absmag_v = +3.84 Starbox detail
age = >10 × 10⁹
mass = 0.5±0.05
radius = 0.23±0.03
gravity=5.15
luminosity = 15.4
temperature = 29300 ± 500Starbox catalog
names = HS 2201+2610Starbox reference
Simbad = V391+Peg
ARICNS =

V391 Pegasi, also cataloged as HS 2201+2610, is a blue-white subdwarf star approximately 4,570 light-years away in the constellation of Pegasus. The star is clarified as an "extreme horizontal branch star." It is small with only half the mass and one-over-four-and-one-thirds the diameter of the Sun. It has luminosity 15.4 times the Sun.Fact|date=September 2007 It could be quite old, perhaps in excess of 10 Gyr. It is a pulsating variable star of the EC 14026 type.

Subdwarf B stars such as V391 Pegasi are thought to be the result of the ejection of the hydrogen envelope of a red giant star at or just before the onset of helium fusion. The ejection left only a tiny amount of hydrogen on the surface - less than 1/1000 of the total stellar mass. The future for the star is to eventually cool down to make a low mass white dwarf. Most stars retain more of their hydrogen after the first red giant phase, and eventually become asymptotic giant branch stars. The reasons for why some stars, like V391 Pegasi, lose so much mass are not well known.

Planetary system

In 2007, a gas giant planet designated V391 Pegasi b was found in orbit by variable timing method. This planet around "extreme horizontal branch" star provided clues about what could actually happen to the planets in our solar system when our Sun turns into a red giant within the next five billion years.

PlanetboxOrbit
exoplanet = b
mass = >3.2±0.7
period = 1170±44
semimajor = 1.7±0.1
eccentricity = 0.00

References

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External links

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