HD 33579 is a white/yellow

hypergiant A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term ''hypergiant'' is defined as luminosity class 0 (zero) in the MKK ...

and one of the brightest stars in the Large Magellanic Cloud (LMC). It is a suspected

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...

. 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. 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 A yellow hypergiant (YHG) is a massive star with an extended atmosphere, a spectral class from A to K, and, starting with an initial mass of about 20–60 solar masses, has lost as much as half that mass. They are amongst the most visually lumi ...

although the spectral type of A3 means it is also described as a white hypergiant. Although HD 33579 has not been formally listed in the

General Catalogue of Variable Stars The General Catalogue of Variable Stars (GCVS) is a list of variable stars. Its first edition, containing 10,820 stars, was published in 1948 by the Academy of Sciences of the USSR and edited by B. V. Kukarkin and P. P. Parenago. Second and thi ...

, analysis of Hipparcos photometry confirmed small amplitude variations in its brightness that had been reported in earlier research. Periods of 620 days and 105 days are found, plus other possible shorter periods. The total amplitude is only around 0.1 magnitudes. A statistical analysis of Hipparcos photometry showed a possible period of 27 days.

References

{{DEFAULTSORT:HD 33579 Stars in the Large Magellanic Cloud A-type hypergiants Dorado (constellation) Large Magellanic Cloud 033579 023718 Durchmusterung objects Alpha Cygni variables