Overview: WOH G64 is a red supergiant located in the Large Magellanic Cloud (LMC). It is notable for its very large radius and cool surface temperature compared with many other luminous stars. Because of its size, temperature and heavy mass loss, it is frequently discussed among the largest and most evolved stars known.

Physical characteristics

Measured properties of WOH G64 indicate an enormous photosphere and a cool effective temperature. Published radius estimates range from roughly 1,800 to over 2,400 times that of the Sun (radius estimates), making it one of the largest known stars (comparative lists). Its effective temperature is near 3,400 K (temperature studies), typifying it as a cool red supergiant. Some analyses suggest irregular or long-period variability and it has been discussed as a possible Mira-like variable (variability note).

Surroundings and mass loss

WOH G64 is embedded in a thick circumstellar dust envelope that extends to about a light year in diameter (envelope size, diameter measurements). Observations of the dust and gas indicate several solar masses of expelled material — estimates around three to nine times the Sun's mass have been reported (mass-loss estimates). This envelope is attributed to strong stellar winds and intense mass-loss episodes in the star's late evolutionary stage (mass-loss mechanisms).

Context and significance

To convey scale, if WOH G64 were placed at the center of the Solar System its photosphere would extend past the orbit of the outer planets: it would engulf or reach as far as Jupiter's orbit (solar-system comparison), in other words enclosing roughly the orbit of Jupiter (Jupiter orbit reference). Such comparisons are useful for public understanding even though exact boundaries depend on uncertain radius and envelope models.

Evolutionary role and observations

WOH G64 represents a late stage in the life of a massive star. Its intense mass loss influences how the star will evolve toward its end state and enriches the surrounding medium with heavy elements and dust. Astronomers study WOH G64 at infrared and radio wavelengths because the dust obscures visible light; modeling the star and its envelope requires combining photometry, spectroscopy and radiative-transfer calculations.

Notable facts

  • Class: red supergiant with very low effective temperature relative to luminous hot stars.
  • Extremely large apparent size in the LMC and among the most voluminous stellar photospheres identified.
  • Associated with a massive dusty envelope produced by sustained stellar wind and episodic ejection.

Because of measurement uncertainties and the influence of circumstellar dust, published numbers for radius, mass-loss and luminosity vary; ongoing observations continue to refine the picture of this remarkable star.