HD 33579

HD 33579 is a white/yellow hypergiant and one of the brightest stars in the Large Magellanic Cloud (LMC). It is a suspected variable star.

HD 33579
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Dorado
Right ascension  5h 5m 55.51232s[1]
Declination −67° 53′ 10.9374″[1]
Apparent magnitude (V) +9.22[2]
Characteristics
Spectral type A3Ia+[3]
U−B color index −0.29[4]
B−V color index +0.14[4]
Variable type α Cygni[2]
Astrometry
Radial velocity (Rv)255.959[5] km/s
Proper motion (μ) RA: 2.31[1] mas/yr
Dec.: −0.46[1] mas/yr
Parallax (π)0.31 ± 0.26[6] mas
Distance~165,000 ly
(~50,000 pc)
Absolute magnitude (MV)−9.57[7]
Details
Mass20–30[8] M☉
Radius380[8] R☉
Luminosity525,000[8] L☉
Surface gravity (log g)0.82±0.21[3] cgs
Temperature7,980[8] K
Metallicity [Fe/H]−0.38±0.14[3] dex
Other designations
HD 33579, CD-68 258, HIP 23718, R76, SK -67 44, AAVSO 0506-68
Database references
SIMBADdata

HD 33579 lies in a part of the Hertzsprung–Russell diagram referred to as the Yellow Evolutionary Void because stars with that combination of luminosity and temperature are extremely unstable. They either expand to become cooler or shed their outer layers completely to become hotter. Yet HD 33579 is relatively stable, hardly even variable. This is thought to be due to its higher mass compared to most stars with similar temperature and luminosity.[3]

HD 33579 is an extremely rare type of star currently evolving for the first time through the yellow evolutionary void from being a blue hypergiant to becoming a red hypergiant. This means the star is often referred to as a yellow hypergiant although the spectral type of A3 means it is also described as a white hypergiant.[3]

Although HD 33579 has not been formally listed in the General Catalogue of Variable Stars, analysis of Hipparcos photometry confirmed small amplitude variations in its brightness that had been reported in earlier research.[9][10][11] Periods of 620 days and 105 days are found, plus other possible shorter periods. The total amplitude is only around 0.1 magnitudes.[2] A statistical analysis of Hipparcos photometry showed a possible period of 27 days.[12]

References
  1. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. Van Leeuwen, F.; Van Genderen, A. M.; Zegelaar, I. (1998). "Hipparcos photometry of 24 variable massive stars (α Cygni variables)". Astronomy and Astrophysics Supplement Series. 128: 117. Bibcode:1998A&AS..128..117V. doi:10.1051/aas:1998129.
  3. Nieuwenhuijzen, H.; De Jager, C. (2000). "Checking the yellow evolutionary void. Three evolutionary critical Hypergiants: HD 33579, HR 8752 & IRC +10420". Astronomy and Astrophysics. 353: 163–176 (2000). Bibcode:2000A&A...353..163N.
  4. "Proceedings of the First European Astronomical Meeting Athens, September 4–9, 1972". 1974. doi:10.1007/978-3-642-65666-8. ISBN 978-3-642-65668-2. Cite journal requires |journal= (help)
  5. Kordopatis, G.; Gilmore, G.; Steinmetz, M.; Boeche, C.; Seabroke, G. M.; Siebert, A.; Zwitter, T.; Binney, J.; De Laverny, P.; Recio-Blanco, A.; Williams, M. E. K.; Piffl, T.; Enke, H.; Roeser, S.; Bijaoui, A.; Wyse, R. F. G.; Freeman, K.; Munari, U.; Carrillo, I.; Anguiano, B.; Burton, D.; Campbell, R.; Cass, C. J. P.; Fiegert, K.; Hartley, M.; Parker, Q. A.; Reid, W.; Ritter, A.; Russell, K. S.; et al. (2013). "The Radial Velocity Experiment (RAVE): Fourth Data Release". The Astronomical Journal. 146 (5): 134. arXiv:1309.4284. Bibcode:2013AJ....146..134K. doi:10.1088/0004-6256/146/5/134.
  6. Gaia Collaboration (2016). "VizieR Online Data Catalog: Gaia DR1 (Gaia Collaboration, 2016)". VizieR On-line Data Catalog: I/337. Originally Published in: Astron. Astrophys. 1337. Bibcode:2016yCat.1337....0G.
  7. Bresolin, Fabio (2003). "Blue Supergiants as a Tool for Extragalactic Distances Empirical Diagnostics". Stellar Candles for the Extragalactic Distance Scale. Lecture Notes in Physics. 635: 149. arXiv:astro-ph/0301179. Bibcode:2003LNP...635..149B. doi:10.1007/978-3-540-39882-0_8. ISBN 978-3-540-20128-1.
  8. Yungelson, L. R.; Van Den Heuvel, E. P. J.; Vink, Jorick S.; Portegies Zwart, S. F.; De Koter, A. (2008). "On the evolution and fate of super-massive stars". Astronomy and Astrophysics. 477: 223. arXiv:0710.1181. Bibcode:2008A&A...477..223Y. doi:10.1051/0004-6361:20078345.
  9. Van Genderen, A. M. (1974). "A Probable Periodicity in the Light Variation of the LMC Supergiant HD 33579". Information Bulletin on Variable Stars. 877: 1. Bibcode:1974IBVS..877....1V.
  10. Van Genderen, A. M. (1979). "Long time baseline VBLUW photometry of four of the most luminous LMC supergiants HD 33579, HD 35343=S Dor, HDE 268757 and HDE 269006. I". Astronomy and Astrophysics Supplement Series. 38: 151. Bibcode:1979A&AS...38..151V.
  11. Grieve, G. R.; Madore, B. F.; Welch, D. L. (1985). "Leavitt variables—Bright variable supergiants and their implications for the distance scale". Astrophysical Journal. 294: 513. Bibcode:1985ApJ...294..513G. doi:10.1086/163318.
  12. Koen, Chris; Eyer, Laurent (2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society. 331: 45. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x.
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