| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Vela |
| Right ascension | 08h42m 16.19252s[2] |
| Declination | −48° 05′ 56.7481″[2] |
| Apparent magnitude (V) | 5.48 - 5.53[3] |
| Characteristics | |
| Spectral type | B1.5V[4] |
| U−B color index | −0.9[4] |
| B−V color index | −0.17[4] |
| Variable type | ELL[3] |
| Astrometry | |
| Radial velocity (Rv) | 42.0±4.5[5] km/s |
| Proper motion (μ) | RA: −3.714±0.128[2] mas/yr Dec.: 4.758±0.138[2] mas/yr |
| Parallax (π) | 0.9479 ± 0.1121 mas[2] |
| Distance | approx. 3,400 ly (approx. 1,100 pc) |
| Absolute magnitude (MV) | −2.32[6] |
| Details[4] | |
| Aa | |
| Mass | 8.5±1.7 M☉ |
| Radius | 5.0±0.3 R☉ |
| Luminosity | 8,700±1,500 L☉ |
| Temperature | 25,000±1,300 K |
| Ab | |
| Mass | 5.4±1.2 M☉ |
| Radius | 3.1±0.3 R☉ |
| Luminosity | 1,400±800 L☉ |
| Temperature | 20,000±2,500 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
HX Velorum, also known as HR 3462 and HD 74455, is a star in the constellation Vela. It is a 5th magnitude star, so it will be faintly visible to the naked eye of an observer far from city lights. It is a variable star, whose brightness varies slightly from magnitude 5.48 to 5.53 over a period of 1.12 days.[3]
In 1981, Robert Shobbrook announced that HR 3462 is a variable star based on observations made in 1976. He correctly classified it as an ellipsoidal variable, but the period he derived, 0.56205±0.00005 days, was a factor of two too short because his data did not allow him to distinguish between primary and secondary minima in the light curve.[8] It was given the variable star designation HX Velorum in 1980.[9] In 1983, Christoffel Waelkens and Frédy Rufener published the correct period of variability, 1.124 days.[10]
HX Velorum is a triple star, consisting of a pair (components A, magnitude 5.5, and B, magnitude 8.28) separated by 0.5 arc seconds. Component A is itself a close binary pair (components Aa and Ab).[11][4] The system's brightness variation is caused by the ellipsoidal Aa and Ab components orbiting each other.[4]
HX Velorum is only about 2 arc minutes from the center of IC 2395, so it appears to be within that cluster. However the Gaia DR3 dataset lists the parallax of HX Velorum as 0.9479±0.1121 mas, yielding a distance of 3,400+500
−300 light years, while the distance to IC 2395 has been estimated to be 4,560±200[12] light years, so HX Velorum might be a foreground object rather than a true cluster member. Mark Blackford et al. concluded HX Velorum is a member of the cluster, but that conclusion was based in part on earlier, significantly different distance estimates for both the star and the cluster.[4]
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