List of most massive stars

From Wikipedia, the free encyclopedia

This is a list of the most massive stars. The list is ordered by solar mass.

Stellar mass is the most important attribute of a star. Combined with chemical compositions, mass determines a star’s luminosity, its physical size, and its ultimate fate.

**List of the heaviest stars**
Star name	Solar Mass
Eta Carinae	150
Pistol Star	150
LBV 1806-20	130
S Doradus	100
Pismis 24-1	100
Cyg OB2-12	92
WR 20ab	80 + 80
R 66	70
R 126	30

[edit] Uncertainties and Caveats

The masses listed in the table are inferred from theory, using difficult measurements of the stars’ temperatures and absolute brightnesses. All the listed masses are uncertain: both the theory and the measurements are pushing their limits. Either measurement, or theory, or both, could be a bit off.

The most reliable listed mass is for WR20a, which was obtained directly. WR20a is a member of a binary star system (two stars orbiting around each other), and it is possible to measure the individual masses of the two stars just by studying their orbital motion, via Kepler’s laws. This involves measuring their radial velocities and also their light curve, as WR20a is in an eclipsing binary.

Massive stars are rare. All the listed stars are many thousands of light years away, and that alone would make measurements difficult. In addition to being far away, it seems that most stars of such extreme mass are surrounded by clouds of outflowing gas. The surrounding gas gets in the way of the already difficult measurements of the stars’ temperatures and brightness, and greatly complicates the already messy issue of measuring their internal chemical composition. Hence these masses are contested, and being a subject of current research, are constantly being revised.

[edit] Eddington’s Size Limit

Astronomers have long theorized that as a protostar grows, that if it exceeds 120 Solar masses, something drastic must happen. Although the limit can be stretched for very early Population III stars, if any stars existed above 120 solar mass, they would challenge current theories of stellar evolution.

The limit on mass arises because stars of greater mass have a higher rate of core energy generation, which is higher far out of proportion to their greater mass. For a sufficiently massive star, the outward pressure of radiant energy generated by Nuclear fusion in the star’s core exceeds the inward pull of its own gravity. This is called the Eddington limit. Beyond this limit, a star ought to push itself apart, or at least shed enough mass to reduce its internal energy generation to a lower, maintainable rate. In theory, a more massive star could not hold itself together, because of the mass loss resulting from the outflow of stellar material.

Studying the Arches cluster, which is the densest known cluster of stars in our galaxy, astronomers have confirmed that stars in that cluster do not occur any larger than about 150 solar masses, or 150 times the mass of our Sun.