HX Velorum

HX Velorum

A light curve for HX Velorum, plotted from TESS data.[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Vela
Right ascension 08h 42m 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]
Distanceapprox. 3,400 ly
(approx. 1,100 pc)
Absolute magnitude (MV)−2.32[6]
Details[4]
Aa
Mass8.5±1.7 M☉
Radius5.0±0.3 R☉
Luminosity8,700±1,500 L☉
Temperature25,000±1,300 K
Ab
Mass5.4±1.2 M☉
Radius3.1±0.3 R☉
Luminosity1,400±800 L☉
Temperature20,000±2,500 K
Other designations
HD 74455, HR 3462, HIP 42712, SAO 220313[7]
Database references
SIMBADdata

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]

  1. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference dr3 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference gcvs was invoked but never defined (see the help page).
  4. ^ a b c d e f g Cite error: The named reference Blackford2019 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference melnik2020 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Shobbrook1981 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Kholopov1981 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Waelkens1983 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference WDS was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Jaehnig2021 was invoked but never defined (see the help page).