Astronomy:BL Crucis

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Short description: Star in the constellation Crux
BL Crucis
Location of BL Crucis (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Crux[1]
Right ascension  12h 27m 28.88s[2]
Declination −58° 59′ 30.4″[2]
Apparent magnitude (V) 5.43[3]
Characteristics
Evolutionary stage AGB[4]
Spectral type M4/5III[5]
Variable type SR[3]
Astrometry
Radial velocity (Rv)71.7±0.9[6] km/s
Proper motion (μ) RA: −19.294[2] mas/yr
Dec.: +4.680[2] mas/yr
Parallax (π)6.8429 ± 0.1942[2] mas
Distance480 ± 10 ly
(146 ± 4 pc)
Absolute magnitude (MV)−0.28[1]
Details
Mass3.6[7] M☉
Radius106[8] R☉
Luminosity1,234[8] L☉
Surface gravity (log g)1.94[7] cgs
Temperature3,320[8] K
Metallicity [Fe/H]−0.33[7] dex
Other designations
CD−58°4560, HD 108396, HIP 60781, HR 4739, SAO 239960[9]
Database references
SIMBADdata

BL Crucis is a red giant and a semiregular variable in the constellation of Crux. A 5th magnitude star, it is visible to the naked eye under good observing conditions. It is 480±10 light-years distant from Earth.

A light curve for BL Crucis, adapted from Tabur et al. (2009)[10]

In 1969, Olin J. Eggen announced that the star, then called HR 4739, is a variable star.[11] It was given its variable star designation, BL Crucis, in 1977.[12] Three periods have been detected in its light curve, 30.7, 42.3 and 43.6 days.[10] The maximum amplitude of variation is 0.35 magnitudes.[3]

An aging red giant, BL Crucis is on the asymptotic giant branch having exhaust both its core hydrogen and core helium. It now fuses hydrogen and helium in separate shells outside the core.[4]

References

  1. ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A  XHIP record for this object at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 Watson, Christopher (25 August 2009). "BL Crucis". AAVSO. http://www.aavso.org/vsx/index.php?view=detail.top&oid=10857. Retrieved 20 July 2014. 
  4. ↑ 4.0 4.1 Eggen, Olin J. (1992). "Asymptotic Giant Branch Stars Near the Sun". The Astronomical Journal 104: 275. doi:10.1086/116239. Bibcode: 1992AJ....104..275E. 
  5. ↑ Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume I. Bibcode: 1975mcts.book.....H. 
  6. ↑ Evans, D. S. (1967). "The Revision of the General Catalogue of Radial Velocities". Determination of Radial Velocities and Their Applications 30: 57. Bibcode: 1967IAUS...30...57E. 
  7. ↑ 7.0 7.1 7.2 Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G. et al. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics 691: A98. doi:10.1051/0004-6361/202451427. Bibcode: 2024A&A...691A..98K. 
  8. ↑ 8.0 8.1 8.2 Fetherolf, Tara; Pepper, Joshua; Simpson, Emilie; Kane, Stephen R.; Močnik, Teo; English, John Edward; Antoci, Victoria; Huber, Daniel et al. (2023). "Variability Catalog of Stars Observed during the TESS Prime Mission". The Astrophysical Journal Supplement Series 268 (1): 4. doi:10.3847/1538-4365/acdee5. Bibcode: 2023ApJS..268....4F. 
  9. ↑ "BL Crucis". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BL+Crucis. 
  10. ↑ 10.0 10.1 Tabur, V.; Bedding, T. R. (2009). "Long-term photometry and periods for 261 nearby pulsating M giants". Monthly Notices of the Royal Astronomical Society 400 (4): 1945–61. doi:10.1111/j.1365-2966.2009.15588.x. Bibcode: 2009MNRAS.400.1945T. 
  11. ↑ Eggen, O. J. (June 1969). "Light Variations of Small Amplitude in the Red Giants of the Disc Population". Information Bulletin on Variable Stars 355. Bibcode: 1969IBVS..355....1E. https://ibvs.konkoly.hu/pub/ibvs/0301/0355.pdf. Retrieved 9 December 2024. 
  12. ↑ Kukarkin, B. V.; Kholopov, P. N.; Fedorovich, V. P.; Kireyeva, N. N.; Kukarkina, N. P.; Medvedeva, G. I.; Perova, N. B. (March 1977). "62nd Name-List of Variable Stars". Information Bulletin on Variable Stars 1248: 1–25. Bibcode: 1977IBVS.1248....1K. https://ibvs.konkoly.hu/pub/ibvs/1201/1248.pdf. Retrieved 9 December 2024. 
  • David H. Levy, Observing variable stars : a guide for the beginner ISBN 0521627559
  • General Catalogue of Variable Stars



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