V391 Pegasi b

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**V391 Pegasi b**
Parent star
Extrasolar planet		List of extrasolar planets
Star		V391 Pegasi
Constellation		Pegasus
Right ascension	(α)	22^h 04^m 12.2^s
Declination	(δ)	+26° 25′ 08″
Distance		4570 ly (1400 pc)
Spectral type		sdB
Orbital elements
Semimajor axis	(a)	1.7±0.1 AU
Eccentricity	(e)	0
Orbital period	(P)	1170±44 d
Angular distance	(θ)	1.214 mas
Longitude of periastron	(ω)	23.5±7.0°
Time of periastron	(T₀)	2,452,418±96 JD
Semi-amplitude	(K)	76.7 m/s
Physical characteristics
Mass	(m)	>3.2±0.7 M_J
Discovery information
Discovery date		Mar-Sept 2007
Discoverer(s)		Silvotti et al.
Detection method		variable timing
Discovery status		Published
Other designations
HS 2201+2610 b

V391 Pegasi b, also known as HS 2201+2610 b, is an extrasolar planet orbiting the star V391 Pegasi approximately 4570 light-years away in the constellation of Pegasus. The planet was discovered by means of variable timing, which measured anomalies in variability of the star caused by a planet. It found to have mass of 3.2 times Jupiter (making the planet a superjovian), semi-major axis of 1.7 AU, and orbital period of 1170 days. The planet was discovered in March 2007 and published in September 2007. Its survival indicates that planets at Earth-like distances can survive their star's red-giant phase, though this is a much larger planet than Earth (about the same size as Jupiter and Saturn).^[1]

[edit] References

R. Silvotti, S. Schuh, R. Janulis, S. Bernabei, R. Ostensen, J.-E. Solheim, I. Bruni, R. Gualandi, T. Oswalt, A. Bonanno, B. Mignemi, the Whole Earth Telescope Xcov23 collaboration (2007). "The O-C diagram of the subdwarf B pulsating star HS2201+2610: detection of a giant planet?". ASP conf. series.
R. Silvotti, S. Schuh, R. Janulis, J.-E. Solheim, S. Bernabei, R. Østensen, T. D. Oswalt, I. Bruni, R. Gualandi, A. Bonanno, G. Vauclair, M. Reed, C.-W. Chen, E. Leibowitz, M. Paparo, A. Baran, S. Charpinet, N. Dolez, S. Kawaler, D. Kurtz, P. Moskalik, R. Riddle & S. Zola (2007). "A giant planet orbiting the 'extreme horizontal branch' star V 391 Pegasi". Nature 449: 189–191. doi:10.1038/nature06143.