V391 Pegasi

V391 Pegasi

A light curve for V391 Pegasi, adapted from Silvotti et al. (2010)[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pegasus
Right ascension 22h 04m 12.1045s[2]
Declination +26° 25′ 07.819″[2]
Apparent magnitude (V) +14.61[3]
Characteristics
Evolutionary stage subdwarf B
Spectral type sdB[4]
Variable type V361 Hydrae (sdBVr)[5]
Astrometry
Proper motion (μ) RA: −4.906(40) mas/yr[2]
Dec.: −3.703(34) mas/yr[2]
Parallax (π)0.7388 ± 0.0327 mas[2]
Distance4,400 ± 200 ly
(1,350 ± 60 pc)
Absolute magnitude (MV)+3.88[4]
Details
Mass0.47[4] M
Radius0.23[4] R
Luminosity34[4] L
Surface gravity (log g)5.4±0.1[6] cgs
Temperature29,300±500[6] K
Age>10[7] Gyr
Other designations
HS 2201+2610, 2MASS J22041211+2625078
Database references
SIMBADdata

V391 Pegasi, also catalogued as HS 2201+2610, is a blue-white subdwarf star approximately 4,400 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 34 times that of the Sun. It could be quite old, perhaps in excess of 10 Gyr. It is a pulsating variable star of the V361 Hydrae type (or also called sdBVr type). It is believed that the star's mass when it was still on the main sequence was between 0.8 and 0.9 times that of the Sun.[7]

  1. ^ Cite error: The named reference SilvottiPhot was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Gaia DR3 was invoked but never defined (see the help page).
  3. ^ Zacharias, N.; Finch, C. T.; Girard, T. M.; Henden, A.; Bartlett, J. L.; Monet, D. G.; Zacharias, M. I. (2012). "VizieR Online Data Catalog: UCAC4 Catalogue (Zacharias+, 2012)". VizieR On-line Data Catalog. Bibcode:2012yCat.1322....0Z.
  4. ^ a b c d e Silvotti, R.; Schuh, S.; Kim, S.L.; Lutz, R.; Reed, M.; Benatti, S.; Janulis, R.; Lanteri, L.; Østensen, R.; Marsh, T.R.; Dhillon, V.S. (March 2018), "The sdB pulsating star V391 Peg and its putative giant planet revisited after 13 years of time-series photometric data.", Astronomy & Astrophysics, 611: A85, arXiv:1711.10942, Bibcode:2018A&A...611A..85S, doi:10.1051/0004-6361/201731473, S2CID 119492634
  5. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S, 1: B/gcvs, Bibcode:2009yCat....102025S
  6. ^ a b R. Østensen; J.-E. Solheim; U. Heber; R. Silvotti; et al. (2001), "Detection of pulsations in three subdwarf B stars", Astronomy and Astrophysics, 368 (1): 175–182, Bibcode:2001A&A...368..175O, doi:10.1051/0004-6361:20000488
  7. ^ a b Silvotti, R.; Schuh, S.; Janulis, R.; Solheim, J. -E.; Bernabei, S.; Østensen, R.; Oswalt, T. D.; Bruni, I.; Gualandi, R.; Bonanno, A.; Vauclair, G.; Reed, M.; Chen, C. -W.; Leibowitz, E.; Paparo, M.; Baran, A.; Charpinet, S.; Dolez, N.; Kawaler, S.; Kurtz, D.; Moskalik, P.; Riddle, R.; Zola, S. (2007), "A giant planet orbiting the 'extreme horizontal branch' star V391 Pegasi" (PDF), Nature, 449 (7159): 189–91, Bibcode:2007Natur.449..189S, doi:10.1038/nature06143, PMID 17851517, S2CID 4342338