FG Virginis

FG Virginis

Visual band light curves for FG Virginis, adapted from Breger et al. (1995)[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Virgo
Right ascension 12h 14m 15.457s[2]
Declination −05° 42′ 59.75″[2]
Apparent magnitude (V) 6.56[3] (6.53 to 6.58)[4]
Characteristics
Evolutionary stage Main sequence
Spectral type A8/9V[5]
U−B color index 0.05[6]
B−V color index 0.277±0.007[3]
Variable type δ Sct[4]
Astrometry
Radial velocity (Rv)16.4±0.6[7] km/s
Proper motion (μ) RA: −85.128 mas/yr[2]
Dec.: 114.628 mas/yr[2]
Parallax (π)11.9261 ± 0.0308 mas[2]
Distance273.5 ± 0.7 ly
(83.8 ± 0.2 pc)
Absolute magnitude (MV)2.10[3]
Details
Mass1.80[8] M☉
Radius2.27[9] R☉
Luminosity11.95[3] L☉
Surface gravity (log g)3.9[10] cgs
Temperature7,425[10] K
Rotation1.74±0.43 d[10]
Rotational velocity (v sin i)21.3±1.0[11] km/s
Other designations
FG Vir, BD−04°3235, HD 106384, HIP 59676, SAO 138664, PPM 195288, WDS J12143-0543A[12]
Database references
SIMBADdata

FG Virginis is a well-studied variable star in the equatorial constellation of Virgo. It is a dim star, near the lower limit of visibility to the naked eye, with an apparent visual magnitude that ranges from 6.53 down to 6.58.[4] The star is located at a distance of 273.5 light years from the Sun based on parallax measurements,[2] and is drifting further away with a radial velocity of +16 km/s.[7] Because of its position near the ecliptic, it is subject to lunar occultations.[13]

The variability of this star was first reported by O. J. Eggen in 1971, who classified it as an ultra-short period cepheid – a proposed category of pulsating stars in the instability strip.[14] It was subsequently grouped in the class of Delta Scuti variables, which show a pulsation period of less than a day.[15] Observations in 1984 by P. Lopez de Coca showed at least one pulsation period with a cycle of 1.9 hours.[16] L. Mantegazza and associates in 1994 were able to detect seven or more pulsation modes, with the previously detected dominant mode being a radial pulsation with a frequency of 12.72 cycles per day.[17]

The star became of interest to astroseismology study because of its relatively slow rotation rate and the numerous modes of pulsation. A multi-site campaign involving the Whole Earth Telescope network was conducted in 1993 to observe this star, which detected ten modes.[1] This was increased to 24 frequencies in 1998,[18] then 67 independent frequencies with 79 total by 2005. Evidence suggests there are many more such modes.[19]

This is an A-type main-sequence star with a stellar classification of A8/9V,[5] but is near the end of its main sequence lifetime.[11] It is classified as a Delta Scuti variable that varies in brightness with an amplitude of 0.040 in visual magnitude and a period of 1.89 hours.[6] Element abundances are similar to the Sun, although there is a slight overabundance of barium and underabundances of sulfur and carbon.[20] It has a projected rotational velocity of 21 km/s, but the actual rotational velocity is likely much higher at around 80 km/s.[11]

  1. ^ a b Cite error: The named reference Breger_et_al_1995 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Houk_Swift_1999 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Rodríguez_et_al_2000 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Breger_Pamyatnykh_2006 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference ima_et_al_2004 was invoked but never defined (see the help page).
  10. ^ a b c Cite error: The named reference Zima_et_al_2006 was invoked but never defined (see the help page).
  11. ^ a b c Cite error: The named reference Breger_Lenz_2019 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Eitter_Beavers_1979 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Eggen1971 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Baglin_et_al_1973 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Lopex_de_Coca_et_al_1984 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Mantegazza_et_al_1994 was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference Breger_et_al_1999 was invoked but never defined (see the help page).
  19. ^ Cite error: The named reference Breger_et_al_2005 was invoked but never defined (see the help page).
  20. ^ Cite error: The named reference Mittermayer_Weiss_2003 was invoked but never defined (see the help page).