Most Massive Star Ever Weighed

ngc3603.jpgThe only time astronomers can determine stellar or planetary masses with any certainty is when the stars or planets occur in systems that are aligned such that we can measure both their velocities using spectra, and we can observe the objects eclipsing one another. Today, a team of astronomers lead by Anthony Moffat (Universite de Montreal) announced they had found the most massive star ever identified. Weighing in at 114 Solar Masses, it is roughly 30 solar masses larger than any previously identified star, and it shares a binary star system with an 84 solar mass star. Looking at these two super luminous stars with their Wolf-Rayet like emissions, astronomers are looking at the site of what may become a black hole – black hole binary system. Maybe.

Super massive stars are rare and short lived, and they are getting more rare every eon. At a certain mass, the nuclear reactions in the core of the star create so much light that the star is actually blown apart by the light (by radiation pressure) more powerfully than the star is held together gravitationally. The effectiveness with which light can blow a star apart is directly related to how much metal the star contains. In the early universe, when metals were more than rare, stars may have grown to a couple hundred solar masses. As successive generations of stars have enriched the universe, the most massive stars have shrank and the universe’s ability to create planets has increased.

These two newly discovered supermassive stars are in the nebula NGC 3603 may mark the upper boundary of what is possible. These stars are will undergo massive amounts of mass loss and will quickly burn through the elements, burning hydrogen through Carbon essentially simultaneously in their cores. The actual mass loss rates will determine if the stars blow themselves to dust, leaving nothing behind, or will blow up and leave behind a black hole or neutron star.

The fate of the binary system will also, in part, be determined by how mass is exchanged between the systems, and how the shock of which ever star explodes first effects the other star.

There are a lot of unknowns. We don’t have a lot of actual observations of super massive stars, and we have even fewer observations of supermassive black hole binaries.

No matter what its future, it is cool to mentally follow the scientific ‘what if’s to imagine the carnage that will someday mark the location of the two newly understood stars.

3 Comments

  1. HoosierHoops June 7, 2007 at 1:16 pm #

    Hi Pam..
    So I thought there was some kind of theoritical limit to the mass of a star….does this star exceed that limit? I saw this really cool email once that compared the size of the earth to the sun and then each succeeding picture showed the size of the sun to other giant stars in order..the graphics looked stunning.. i think i deleted it..d’uh!
    First time visitor, your site is great..
    Kind Regards,
    Bill

  2. pamela June 7, 2007 at 1:24 pm #

    Hi Bill,

    Thanks for the comment! There are theoretical limits, but the vary as the content of the star varies (less metal, more mass is possible – more metal, less mass is possible). In the present day universe, a star currently forming is estimated to become unstable around 150 solar masses. Above this limit, the light/radiation pressure will blow mass away with more force than gravity will bind the mass to the star.

    Cheers,
    Pamela

  3. HoosierHoops June 7, 2007 at 4:34 pm #

    Well I just read your entire blog..until i came across the personal stuff I had no idea what a deep and thoughtful person you are..

    “But, I believe there is room in the universe for a God. And this is an uncomfortable place to be. Between the Romans and Daniel’s lions…”

    there probably isn’t room in the universe for God..I’ve always figured the universe was a small bubble in his living room..Every night when i look into the sky i am amazed at the power, beauty and genius of where we live…I’m not what you would call a christian but I’m not so stupid to think somebody didn’t make this world..Isn’t That what you smart scientists keep telling us? without a reaction nothing happens..ummm. that’s forever..just empty space..nothing happens
    ( gosh a jock smarter than a scientist) :)well i really enjoyed reading your stuff..you have truely inspired me today.. But now it’s off to a basketball game….
    I’ll stop by again sometime….

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