The most
massive star known in the universe has been discovered and "weighed,"
astronomers announced today.
The star, part
of a binary
system, topped the scales at 114 times the mass of the sun.
Though
astronomers suspected that stars with masses up to 150 times the mass of the
sun must exist, this discovery marks the first time a star has broken the 100-solar-mass
barrier. The previous record holder was only a measly 83 solar masses.
The newly
weighed star, known simply as A1, is the brightest hot star at the heart of a
giant, but dense, young star cluster called NGC 3603, which lies 20,000 light-years
from Earth. The star's companion has a mass 84 times that of the sun.
These massive
stars were "weighed" by inspecting their orbits with the Very Large
Telescope and combining that data with eclipses observed by the Hubble Space
Telescope.
Stars have
a mass limit of 150 solar masses because above that, the pressure pushing
outward from the star overwhelms the inward pull of gravity and causes the star
to become unstable.
In the early
universe, however, stars with masses up to several hundred times that of
the sun are believed to have existed because the pressure in the stars was not
as high because the heavier elements had not yet been "cooked" by the nuclear
fusion taking place in the cores of stars.
The
discovery was announced at the annual meeting of the Canadian Astronomical
Society.
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