HY Velorum
Star in the constellation Vela
From Wikipedia, the free encyclopedia
HY Velorum is a binary star[7] system in the southern constellation of Vela. It is a dim star but visible to the naked eye with an apparent visual magnitude of 4.83.[5] The distance to this system, as estimated from its annual parallax shift of 7.1 mas,[2] is 460 light years. HY Vel most likely forms a gravitationally bound pair with the magnitude 5.45 binary system KT Vel (HD 74535);[12] both are members of the IC 2391 open cluster.[13] As of 1998, HY Vel and KT Vel had an angular separation of 76.1″ along a position angle of 311°.[14]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Vela |
| Right ascension | 08h 42m 25.38667s[2] |
| Declination | −53° 06′ 50.3324″[2] |
| Apparent magnitude (V) | 4.81 - 4.86[3] |
| Characteristics | |
| Spectral type | B3 IV[4] |
| B−V color index | −0.173±0.007[5] |
| Variable type | SPB[3] |
| Astrometry | |
| Radial velocity (Rv) | +15.6±0.2[5] km/s |
| Proper motion (μ) | RA: −24.83[6] mas/yr Dec.: +23.21[6] mas/yr |
| Parallax (π) | 7.1141±0.2302 mas[2] |
| Distance | 460 ± 10 ly (141 ± 5 pc) |
| Absolute magnitude (MV) | −1.25[5] |
| Orbit[7] | |
| Period (P) | 8.378±0.001 d |
| Eccentricity (e) | 0.24±0.04 |
| Periastron epoch (T) | 2450741.3 ± 0.2 HJD |
| Argument of periastron (ω) (secondary) | 93±9° |
| Semi-amplitude (K1) (primary) | 8.0±0.3 km/s |
| Details | |
| HY Vel Aa | |
| Mass | 5.4[8] M☉ |
| Luminosity | 830+927 −743[8] L☉ |
| Surface gravity (log g) | 4.07[9] cgs |
| Temperature | 16,865+235 −231[8] K |
| Metallicity [Fe/H] | 0.03±0.02[9] dex |
| Rotational velocity (v sin i) | 45[8] km/s |
| Age | 179[10] Myr |
| Other designations | |
| HY Vel, CPD−52° 1607, HD 74560, HIP 42726, HR 3467, SAO 236205, WDS J08424-5307A[11] | |
| Database references | |
| SIMBAD | data |
This is a single-lined spectroscopic binary system with an orbital period of 8.4 days and an eccentricity of 0.24. The visible component has an a sin i value of 0.006 AU, where a is the semimajor axis and i is the (unknown) orbital inclination to the line of sight.
In 1979, Shyam M. Jakate announced the discovery that the star's brightness varies.[15] It was given its variable star designation, HY Velorum, in 1981.[16] The primary, which is the variable star, is a slowly pulsating B-type star having at least three pulsational modes, with the dominant mode showing a frequency of 0.64472 cycles per day,[7] corresponding to the catalogued period of 1.55106 days.[3] It has a stellar classification of B3 IV, matching a B-type subgiant star.[4]