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EQ Virginis is a single[10] variable star in the equatorial constellation of Virgo. It has a baseline visual apparent magnitude of 9.36,[3] but is a flare star that undergoes sporadic bursts of brightening. The star is located at a distance of 67 light-years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −23 km/s.[2] It is a member of the IC 2391 moving group[11] of stars, which is between 30 and 50 million years old.[8]

EQ Virginis

A light curve for EQ Virginis, plotted from Kepler data[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo
Right ascension 13h 34m 43.2063s[2]
Declination −08° 20′ 31.3353″[2]
Apparent magnitude (V) 9.36[3]
Characteristics
Spectral type K5Ve[3]
Variable type UV Cet + BY Dra[4]
Astrometry
Radial velocity (Rv)−23.16±0.16[2] km/s
Proper motion (μ) RA: −286.577±0.110 mas/yr[2]
Dec.: −91.866±0.083 mas/yr[2]
Parallax (π)48.7322 ± 0.0587 mas[2]
Distance66.93 ± 0.08 ly
(20.52 ± 0.02 pc)
Absolute magnitude (MV)10.51
Details
Mass0.68[5] M☉
Radius0.62+0.02
−0.04[2] R☉
Luminosity0.136±0.001[2] L☉
Surface gravity (log g)4.49[6] cgs
Temperature4,224±80[6] K
Metallicity [Fe/H]−0.144[7] dex
Rotation3.9±0.1[7] days
Rotational velocity (v sin i)2.06[7] km/s
Age30-50[8] Myr
Other designations
EQ Vir, BD−07°3646, GJ 517, HD 118100, HIP 66252, SAO 139419, LTT 5253, PLX 3101, Ross 478[9]
Database references
SIMBADdata
ARICNSdata

This is an orange-hued K-type main-sequence star with a stellar classification of K5Ve,[3] where the 'e' suffix indicates emission lines in the spectrum. It is a young, rapidly rotating star with a mean magnetic field strength of 2,500±300 G.[12] The star is classified as an eruptive variable of the UV Ceti type and a BY Draconis variable.[4] It shows strong chromospheric activity with extensive star spots that, on average, cover ~24% of the surface.[7] The star displays a strong X-ray emission.[12]


References


  1. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  2. 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.
  3. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  4. Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. GCVS 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S.
  5. Luck, R. Earle (March 2018). "Abundances in the Local Region. III. Southern F, G, and K Dwarfs". The Astronomical Journal. 155 (3): 31. Bibcode:2018AJ....155..111L. doi:10.3847/1538-3881/aaa9b5. 111.
  6. Casagrande, L.; et al. (2011). "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey". Astronomy & Astrophysics. 530 (A138): 21. arXiv:1103.4651. Bibcode:2011A&A...530A.138C. doi:10.1051/0004-6361/201016276. S2CID 56118016.
  7. Morris, Brett M.; et al. (September 2019). "Stellar Properties of Active G and K Stars: Exploring the Connection between Starspots and Chromospheric Activity". The Astronomical Journal. 158 (3): 16. arXiv:1907.00423. Bibcode:2019AJ....158..101M. doi:10.3847/1538-3881/ab2e04. S2CID 195767281. 101.
  8. Paulson, Diane B.; Yelda, Sylvana; Allen, Peter R.; Kilkenny, David; Liebert, James; Hawley, Suzanne L.; Fraser, Oliver J.; Covey, Kevin R.; Lowrance, Patrick; Kirkpatrick, J. Davy; Burgasser, Adam J. (2006). "Differential Radial Velocities and Stellar Parameters of Nearby Young Stars". The Publications of the Astronomical Society of the Pacific. 118 (843): 706–715. arXiv:astro-ph/0605433. Bibcode:2006PASP..118..706P. doi:10.1086/504115. S2CID 16194615.
  9. "HD 118100". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-11-15.
  10. Halbwachs, J. -L; et al. (2018). "Multiplicity among solar-type stars. IV. The CORAVEL radial velocities and the spectroscopic orbits of nearby K dwarfs". Astronomy and Astrophysics. 619: A81. arXiv:1808.04605. Bibcode:2018A&A...619A..81H. doi:10.1051/0004-6361/201833377. S2CID 119437322.
  11. Montes, D.; et al. (2001). "Late-type members of young stellar kinematic groups - I. Single stars". Monthly Notices of the Royal Astronomical Society. 328 (1): 45–63. arXiv:astro-ph/0106537. Bibcode:2001MNRAS.328...45M. doi:10.1046/j.1365-8711.2001.04781.x. S2CID 55727428.
  12. Saar, S. H.; et al. (March 1986). "The Magnetic Field of the BY Draconis Flare Star EQ Virginis". Astrophysical Journal. 302: 777. Bibcode:1986ApJ...302..777S. doi:10.1086/164040.

На других языках

- [en] EQ Virginis

[ru] EQ Девы

EQ Девы (EQ Virginis) — звезда в зодиакальном звездии Девы. EQ Девы имеет видимую звёздную величину +9.37m[2], и не может наблюдаться невооружённым глазом.


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