Astronomy:EQ Virginis
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[2] mas/yr Dec.: −91.866±0.083[2] mas/yr |
| Parallax (π) | 48.7322 ± 0.0587[2] mas |
| Distance | 66.93 ± 0.08 ly (20.52 ± 0.02 pc) |
| Absolute magnitude (MV) | 10.51 |
| Details | |
| Mass | 0.68[5] M☉ |
| Radius | 0.62+0.02 −0.04[2] R☉ |
| Luminosity | 0.136±0.001[2] L☉ |
| Surface gravity (log g) | 4.49[6] cgs |
| Temperature | 4,224±80[6] K |
| Metallicity [Fe/H] | −0.144[7] dex |
| Rotation | 3.9±0.1[7] days |
| Rotational velocity (v sin i) | 2.06[7] km/s |
| Age | 30-50[8] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
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]
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
- ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 3.3 Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series 71: 245, doi:10.1086/191373, Bibcode: 1989ApJS...71..245K.
- ↑ 4.0 4.1 Samus, N. N. et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. GCVS 5.1 61 (1): 80–88. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S.
- ↑ Luck, R. Earle (March 2018). "Abundances in the Local Region. III. Southern F, G, and K Dwarfs". The Astronomical Journal 155 (3): 31. doi:10.3847/1538-3881/aaa9b5. 111. Bibcode: 2018AJ....155..111L.
- ↑ 6.0 6.1 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. doi:10.1051/0004-6361/201016276. Bibcode: 2011A&A...530A.138C.
- ↑ 7.0 7.1 7.2 7.3 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. doi:10.3847/1538-3881/ab2e04. 101. Bibcode: 2019AJ....158..101M.
- ↑ 8.0 8.1 Paulson, Diane B.; Yelda, Sylvana; Allen, Peter R.; Kilkenny, David; Liebert, James; Hawley, Suzanne L.; Fraser, Oliver J.; Covey, Kevin R. et al. (2006). "Differential Radial Velocities and Stellar Parameters of Nearby Young Stars". The Publications of the Astronomical Society of the Pacific 118 (843): 706–715. doi:10.1086/504115. Bibcode: 2006PASP..118..706P.
- ↑ "HD 118100". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+118100.
- ↑ 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. doi:10.1051/0004-6361/201833377. Bibcode: 2018A&A...619A..81H.
- ↑ 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. doi:10.1046/j.1365-8711.2001.04781.x. Bibcode: 2001MNRAS.328...45M.
- ↑ 12.0 12.1 Saar, S. H. et al. (March 1986). "The Magnetic Field of the BY Draconis Flare Star EQ Virginis". Astrophysical Journal 302: 777. doi:10.1086/164040. Bibcode: 1986ApJ...302..777S.
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