| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Virgo |
| Right ascension | 14h 12m 15.80569s[2] |
| Declination | +02° 24′ 33.9342″[2] |
| Apparent magnitude (V) | 4.99[3](4.92–5.07)[4] |
| Characteristics | |
| Spectral type | ApSi[5] orB8.5 Vp Si[6] |
| B−Vcolor index | −0.118±0.006[3] |
| Variable type | α2 CVn[4] |
| Astrometry | |
| Radial velocity (Rv) | −2.0±7.4[7] km/s |
| Proper motion (μ) | RA: −43.049[2]mas/yr Dec.: +26.081[2]mas/yr |
| Parallax (π) | 13.9366±0.2601 mas[2] |
| Distance | 234 ± 4 ly (72 ± 1 pc) |
| Absolute magnitude (MV) | 0.50[3] |
| Details[8] | |
| Mass | 3.06±0.06 M☉ |
| Radius | 2.06±0.14 R☉ |
| Luminosity | 100±11 L☉ |
| Surface gravity (log g) | 4.30±0.06 cgs |
| Temperature | 12,750±250 K |
| Rotation | 0.5207137±0.0000010 d[9] |
| Rotational velocity (v sin i) | 145±3 km/s |
| Other designations | |
| CU Vir,BD+03°2867,FK5 3127,HD 124224,HIP 69389,HR 5313,SAO 120339,ADS 9152 A,WDS J14123+0225A[10] | |
| Database references | |
| SIMBAD | data |
CU Virginis is a single[11]star in the equatorialconstellation ofVirgo.[12] It has anapparent visual magnitude of 4.99,[3] which is bright enough to be faintly visible to thenaked eye. The distance to this star can be estimated from its annualparallax shift of13.9 mas,[2] yielding a separation of 234 light years.
This is one of the best studiedAp stars.[13] It has astellar classification of Ap Si[5] with stronglines of silicon and weak helium lines. The star is a fast rotator with a period of 0.52 days and anaxis that is inclined by46.5°±4.1° to theline of sight from the Earth.[8] In 1956, Robert Hardie discovered that the star's brightnessvaries.[14] Both thespectrum and luminosity of the star vary with the rotation,[13] and it is classified as aα2 Canum Venaticorum variable with thedesignation CU Virginis (CU Vir).[4] There is some evidence that the rotation period may vary slightly over a timescale measured in decades.[15] Such changes have been observed to occur in glitches, rather than varying constantly.[13]
CU Virginis has three times themass of the Sun and double theSun's radius. It is radiating 100 times theSun's luminosity from itsphotosphere at aneffective temperature of 12,750 K.[8] The star has a strongmagnetic field, placing it in the class of magneticchemically peculiar stars. The polar magnetic field has a strength of about3 kG.[13] The magnetic pole may be displaced by 87° from the axis of rotation, and the effective magnetic field is seen to vary over the course of a rotation.[13] The mean surface magnetic field varies over the range1.2–3.2 kG.[16]
This star is aradio emitter, with the emission beingmodulated by the rotational phase. This emission is believed to begyrosynchrotron radiation emitted by mildlyrelativistic (Lorentz factor of γ ≤ 2) electrons trapped in themagnetosphere". Two pulses of 100%circularly polarized radio energy are detected each rotation, which may be produced via an electroncyclotronmaser process. These polarized beams are then refracted as they pass through coldplasma in the star's magnetosphere.[13]
