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]

References

  1. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 19 March 2023.
  2. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
  4. 1 2 3 4 5 6 7 Blackford, M. G.; Erdem, A.; Sürgit, D.; Özkardeş, B.; Budding, E.; Butland, R.; Demircan, O. (July 2019). "Absolute parameters of young stars: HX Velorum". Monthly Notices of the Royal Astronomical Society. 487 (1): 161–167. Bibcode:2019MNRAS.487..161B. doi:10.1093/mnras/stz1136.
  5. ↑ Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  6. ↑ Melnik, A. M.; Dambis, A. K. (2020). "Distance scale for high-luminosity stars in OB associations and in field with Gaia DR2. Spurious systematic motions". Astrophysics and Space Science. 365 (7): 112. arXiv:2006.14649. Bibcode:2020Ap&SS.365..112M. doi:10.1007/s10509-020-03827-0. S2CID 220128144.
  7. ↑ "V* HX Vel -- Double or Multiple Star". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-03-18.
  8. ↑ Shobbrook, R. R. (July 1981). "Short period variability of some early B stars". Monthly Notices of the Royal Astronomical Society. 196 (2): 129–134. Bibcode:1981MNRAS.196..129S. doi:10.1093/mnras/196.2.129.
  9. ↑ Kholopov, P. N.; Samus, N. N.; Kukarkina, N. P.; Medvedeva, G. I.; Perova, N. B. (February 1981). "65th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 1921: 1. Bibcode:1981IBVS.1921....1K. Retrieved 21 March 2023.
  10. ↑ Waelkens, C.; Rufener, F. (May 1983). "An observational study of the influence of close companions on the pulsations of beta Cephei stars". Astronomy and Astrophysics. 121: 45–50. Bibcode:1983A&A...121...45W.
  11. ↑ "The Washington Double Star Catalog". The Washington Double Star Catalog. Georgia State University. Retrieved 21 March 2023.
  12. ↑ Jaehnig, Karl; Bird, Jonathan; Holley-Bockelmann, Kelly (December 2021). "Membership Lists for 431 Open Clusters in Gaia DR2 Using Extreme Deconvolution Gaussian Mixture Models". The Astrophysical Journal. 923 (1): 129. arXiv:2108.02783. Bibcode:2021ApJ...923..129J. doi:10.3847/1538-4357/ac1d51.
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