The variability of this star was first reported byO. J. Eggen in 1971, who classified it as an ultra-short periodcepheid – a proposed category ofpulsating stars in theinstability strip.[14] It was subsequently grouped in the class ofDelta Scuti variables, which show a pulsation period of less than a day.[15] Observations in 1984 byP. 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 toastroseismology study because of its relatively slow rotation rate and the numerous modes of pulsation. A multi-site campaign involving theWhole 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 anA-type main-sequence star with astellar 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 anamplitude 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 aprojected rotational velocity of 21 km/s, but the actual rotational velocity is likely much higher at around 80 km/s.[11]
^abBreger, 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.
^abHouk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars",Michigan Spectral Survey,5,Bibcode:1999MSS...C05....0H.
^abcBreger, 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.
^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.
^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.
^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.
Haas, P. (2011), "Analyses of Crawford's uvby β calibrations using the pulsational variations of FG Vir",Communications in Asteroseismology,162: 3,Bibcode:2011CoAst.162....3H,doi:10.1553/cia162s3.
Lenz, P.; et al. (April 2008), "Determination of intrinsic mode amplitudes of the δ Scuti stars FG Vir and 44 Tau",Communications in Asteroseismology,153:40–48,Bibcode:2008CoAst.153...40L,doi:10.1553/cia_153s40.
Zima, W. (July 2001), "The Spectroscopic and Photometric DSN Campaign 2002 of FG Vir",Communications in Asteroseismology,140:57–58,Bibcode:2001CoAst.140...57Z.
Dziembowski, W. A.; et al. (November 1998), Kjeldsen, H.; Bedding, T. R. (eds.), "Oscillations in XX Pyx and FG VIR and the prospects for asteroseismology of delta Scuti stars from space",The First MONS Workshop: Science with a Small Space Telescope, held in Aarhus, Denmark, June 29–30, 1998, Aarhus Universitet, p. 127,Bibcode:1998mons.proc..127D.
Viskum, M.; et al. (July 1998), "Oscillation mode identifications and models for the delta Scuti star FG Virginis",Astronomy & Astrophysics,335:549–560,arXiv:astro-ph/9804218,Bibcode:1998A&A...335..549V.
Breger, M.; et al. (March 1998), "The delta Scuti star FG Vir. III. The 1995 multisite campaign and the detection of 24 pulsation frequencies",Astronomy & Astrophysics,331:271–279,Bibcode:1998A&A...331..271B.
Breger, M.; et al. (May 1996), "The δ Scuti star FG Virginis. II. A search for high pulsation frequencies",Astronomy & Astrophysics,309:197–202,Bibcode:1996A&A...309..197B.
Guzik, J. A.; Bradley, P. A. (September 1995), "Models and mode identifications of the Delta Scuti Star FG Vir",Delta Scuti Star Newsletter,9 (9):7–14,Bibcode:1995DSSN....9....7G.
Breger, M. (September 1995), "The 1995 FG VIR campaign: will 550 hours of new data and 19 frequencies be enough to do asteroseismology?",Delta Scuti Star Newsletter,9 (9):14–17,Bibcode:1995DSSN....9...14B.
Dawson, D. W.; et al. (June 1995), "A Photometric Study of the delta Scuti Star FG Virginis Undertaken during 1985/6",Publications of the Astronomical Society of the Pacific,107:517–520,Bibcode:1995PASP..107..517D,doi:10.1086/133585,S2CID123547347.
Dawson, D. W. (March 1990), "The Period Structure of FG Virginis",Bulletin of the American Astronomical Society,22: 831,Bibcode:1990BAAS...22..831D.
Gonzalez-Bedolla, S. F.; Rodriguez, E. (February 1990), "FG Vir, Additional Photoelectric Observations",Information Bulletin on Variable Stars,3426: 1,Bibcode:1990IBVS.3426....1G.
