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FG Virginis

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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]

References

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  1. ^ a b Breger, M.; et al. (May 1995), "The δ Scuti star FG Virginis. I. Multiple pulsation frequencies determined with a combined DSN/WET campaign", Astronomy & Astrophysics, 297: 473, Bibcode:1995A&A...297..473B.
  2. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021), "Gaia Early Data Release 3: Summary of the contents and survey properties", Astronomy & Astrophysics, 649: A1, arXiv:2012.01533, Bibcode:2021A&A...649A...1G, doi:10.1051/0004-6361/202039657, S2CID 227254300 (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  3. ^ a b c d Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  4. ^ a b c Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  5. ^ a b Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
  6. ^ a b Rodríguez, E.; et al. (June 2000), "A revised catalogue of delta Sct stars", Astronomy & Astrophysics Supplement Series, 144 (3): 469–474, Bibcode:2000A&AS..144..469R, doi:10.1051/aas:2000221, hdl:10261/226673.
  7. ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018), "Gaia Data Release 2: Summary of the contents and survey properties", Astronomy & Astrophysics, 616, A1, arXiv:1804.09365, Bibcode:2018A&A...616A...1G, doi:10.1051/0004-6361/201833051 Gaia DR2 record for this source at VizieR.
  8. ^ Breger, M.; Pamyatnykh, A. A. (May 2006), "Amplitude variability or close frequencies in pulsating stars - the δ Scuti star FG Vir", Monthly Notices of the Royal Astronomical Society, 368 (2): 571–578, arXiv:astro-ph/0602037, Bibcode:2006MNRAS.368..571B, doi:10.1111/j.1365-2966.2006.10119.x, S2CID 18429588.
  9. ^ Zima, W.; et al. (June 2004), "Moment Method and Pixel-by-Pixel Method: Complementary Mode Identification I. Testing FG Vir-like pulsation modes", Communications in Asteroseismology, 144: 5–22, Bibcode:2004CoAst.144....5Z, doi:10.1553/cia144s5.
  10. ^ a b c Zima, W.; et al. (August 2006), "A new method for the spectroscopic identification of stellar non-radial pulsation modes. II. Mode identification of the δ Scuti star FG Virginis", Astronomy & Astrophysics, 455 (1): 235–246, arXiv:astro-ph/0606515, Bibcode:2006A&A...455..235Z, doi:10.1051/0004-6361:20064877, S2CID 54036626.
  11. ^ a b c Breger, M.; Lenz, P. (February 2019), "Photometric data by the Delta Scuti Network. II. EE Cam, FG Vir, 44 Tau", The Journal of Astronomical Data, 25 (1): 6, Bibcode:2019JAD....25....1B.
  12. ^ "FG Vir", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2022-06-14.
  13. ^ Eitter, J. J.; Beavers, W. I. (June 1979), "Lunar occultation summary. III", Astrophysical Journal Supplement Series, 40: 475–486, Bibcode:1979ApJS...40..475E, doi:10.1086/190595. See event no. 528.
  14. ^ Eggen, O. J. (December 1971), "The Nature of the Blue Stragglers in the Old Disk Population", Publications of the Astronomical Society of the Pacific, 83 (496): 762, Bibcode:1971PASP...83..762E, doi:10.1086/129212, S2CID 120025134.
  15. ^ Baglin, A.; et al. (March 1973), "Delta Scuti stars", Astronomy & Astrophysics, 23: 221, Bibcode:1973A&A....23..221B.
  16. ^ Lopez de Coca, P.; et al. (January 1984), "Narrow Band Photometry of FG Vir", Information Bulletin on Variable Stars, 2465: 1, Bibcode:1984IBVS.2465....1L.
  17. ^ Mantegazza, L.; et al. (July 1994), "Simultaneous intensive photometry and high resolution spectroscopy of δ Scuti stars I. Mode typing of HD 106384 = FG Virginis", Astronomy & Astrophysics, 287: 95–104, Bibcode:1994A&A...287...95M.
  18. ^ Breger, M.; et al. (January 1999), "The delta Scuti star FG Virginis. IV. Mode identifications and pulsation modelling", Astronomy & Astrophysics, 341: 151–162, arXiv:astro-ph/9811338, Bibcode:1999A&A...341..151B.
  19. ^ Breger, M.; et al. (June 2005), "Detection of 75+ pulsation frequencies in the δ Scuti star FG Virginis", Astronomy & Astrophysics, 435 (3): 955–965, arXiv:astro-ph/0502073, Bibcode:2005A&A...435..955B, doi:10.1051/0004-6361:20042480, S2CID 119042031.
  20. ^ Mittermayer, P.; Weiss, W. W. (September 2003), "Atmospheric properties and abundances of the delta Scuti star FG Virginis", Astronomy & Astrophysics, 407 (3): 1097–1101, Bibcode:2003A&A...407.1097M, doi:10.1051/0004-6361:20030930, S2CID 123022971.

Further reading

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