HD 110432
Location of BZ Crucis (circled). The other star shown overlapping/underlying the dark nebula is HD 109000 (HR 4771) which is a red/brown star about half the distance to the nebula, having parallax of 12.8 ± 0.05 thus about 250 light years away[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Crux
Right ascension 12h 42m 50.2656s[1]
Declination −63° 03′ 31.048″[1]
Apparent magnitude (V) 5.24 - 5.45[2]
Characteristics
Spectral type B1IVe[3]
U−B color index −0.82[4]
B−V color index +0.27[4]
Variable type γ Cas[2]
Astrometry
Radial velocity (Rv)+35[5] km/s
Proper motion (μ) RA: −12.512[1] mas/yr
Dec.: −3.984[1] mas/yr
Parallax (π)2.3834 ± 0.1228 mas[1]
Distance1,370 ± 70 ly
(420 ± 20 pc)
Absolute magnitude (MV)−2.56[6]
Details
Mass9.6[3] M☉
Radius6.5±1.2[7] R☉
Luminosity1,153[1] L☉
Surface gravity (log g)3.5–3.9[3] cgs
Temperature22,510–25,000[3] K
Rotational velocity (v sin i)300–400[3] km/s
Other designations
BZ Cru, HR 4830, CD-62 671, HD 110432, GCTP, SAO 252002, FK5 3015, HIP 62027.[8]
Database references
SIMBADdata
BZ Crucis is the bright star between the open clusters NGC 4609 and Hogg 15

HD 110432 is a Be star in the south-east of Crux, behind the center of the southern hemisphere's dark Coalsack Nebula. It has a stellar classification of B1IVe, which means it is a subgiant star of class B that displays emission lines in its spectrum. This is a variable star of the Gamma Cassiopeiae type, indicating it is a shell star with a circumstellar disk of gas about the equator, and has the variable star designation BZ Crucis. It is not known to be a member of a binary system, although it is probably a member of the open cluster NGC 4609. This star is moderately luminous in the X-ray band, with a variable energy emission of 1032–33 erg s−1 in the range 0.2−12 keV. The X-ray emission may be caused by magnetic activity, or possibly by accretion onto a white dwarf companion.[3]

A visual band light curve for BZ Crucis, adapted from Sarty et al. (2011)[9]

Distance

The distance of 388 pc published in the 2007 new Hipparcos reduction is over twice the distance of the Coalsack Nebula.[10] The distance from Gaia Data Release 2 is even further at 420 pc.[1]

References

  1. 1 2 3 4 5 6 7 8 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 1 2 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  3. 1 2 3 4 5 6 Lopes de Oliveira, R.; et al. (November 2007). "On the X-ray and optical properties of the Be star HD 110432: a very hard-thermal X-ray emitter". Astronomy and Astrophysics. 474 (3): 983–996. arXiv:astro-ph/0701767. Bibcode:2007A&A...474..983L. doi:10.1051/0004-6361:20077295. S2CID 14593244.
  4. 1 2 Cousins, A. W. J. (1973). "UBV photometry of some southern stars". Monthly Notes of the Astronomical Society of Southern Africa. 32: 11. Bibcode:1973MNSSA..32...11C.
  5. ↑ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E.
  6. ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
  7. ↑ Stee, Ph; Meilland, A.; Bendjoya, Ph.; Millour, F.; Smith, M.; Spang, A.; Duvert, G.; Hofmann, K. -H.; Massi, F. (2013). "Evidence of an asymmetrical Keplerian disk in the Brγ and He I emission lines around the be star HD 110432". Astronomy and Astrophysics. 550: A65. arXiv:1301.2877. Bibcode:2013A&A...550A..65S. doi:10.1051/0004-6361/201220302. S2CID 11256230.
  8. ↑ "HR 4830 -- Be Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-12-09.
  9. ↑ Sarty, Gordon E.; Pilecki, Bogumil; Reichart, Daniel E.; Ivarsen, Kevin M.; Haislip, Joshua B.; Nysewander, Melissa C.; LaCluyze, Aaron P.; Johnston, Helen M.; Shobbrook, Robert R.; Kiss, László L.; Wu, Kinwah (August 2011). "Photometric observations of three high mass X-ray binaries and a search for variations induced by orbital motion". Research in Astronomy and Astrophysics. 11 (8): 947–964. arXiv:1105.2025. Bibcode:2011RAA....11..947S. doi:10.1088/1674-4527/11/8/007. S2CID 250669202. Retrieved 17 December 2021.
  10. ↑ Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
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