Most Massive Star Discovered
Hubble Space Telescope images of the young star cluster NGC 3603 showing the position of the newly-weighed most massive star "A1" and its companion "C".
Credit: HST/Universite de Montreal

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.