Summary
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]
| 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] |
| 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 |
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 edit
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
- ^ a b c d e f g h 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.
- ^ a b c d 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, S2CID 123149047.
- ^ a b Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. GCVS 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 255195566.
- ^ 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. S2CID 125765376. 111.
- ^ a b 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.
- ^ a b c d 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.
- ^ a b 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.
- ^ "HD 118100". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-11-15.
- ^ 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.
- ^ 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.
- ^ a b 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.