EQ Virginis
Star in the constellation Virgo
From Wikipedia, the free encyclopedia
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 | |
| EQ Vir, BD−07°3646, GJ 517, HD 118100, HIP 66252, SAO 139419, LTT 5253, PLX 3101, Ross 478[9] | |
| 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] In 1971, Sylvio Ferraz-Mello and Carlos Alberto Pinto Coelho de Oliveira Torres discovered that the star, then called HD 118100, is a variable star.[13] It was given its variable star designation, EQ Virginis, in 1972.[14] 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]