Yet another record

[derekmcd]

<p>Busy day for astronomers...</p><p><font face="Verdana, Helvetica, sans-serif" size="3" color="#1b4872"><strong>Most Massive Star in Class By Itself </strong><br /><font face="Verdana, Helvetica, sans-serif" size="1" color="#333333"><strong>By Clara Moskowitz</strong><br />Staff Writer<br /></font></font><font face="arial,helvetica" size="1" color="#330066">posted: 19 September 2008<br />02:49 pm ET</font><br /> <a name="beginstory"></a> <font face="arial" size="2"> <font face="arial"> <div class="Section1"> <p class="MsoNormal">Astronomers have confirmed the weight of the most massive star in the galaxy.</p> <p class="MsoNormal">This behemoth, estimated to be roughly 116 times the mass of the sun, dwarfs most other stars in the galaxy. In fact, the next most massive star is about 89 solar masses, and it is a gravitationally bound sister to the record setter.</p> <p class="MsoNormal">The next most massive ever weighed is 83 solar masses. Theory holds that stars can be up to about 150 solar masses.</p> <p class="MsoNormal">Discovery of the record-setting stars were first announced last year. The new measurements are rough, and the stars might turn out to be considerably heavier or lighter.</p> <p class="MsoNormal">"A star having a little over a hundred times more material in it than the sun is rare," said researcher Anthony F. J. Moffat of the Universite de Montreal. "For every star like it you get tens of thousands of stars like the sun formed. So finding them is hard. That's why very few have been known and measured."</p> <p class="MsoNormal">Moffat, with Olivier Schnurr, Jules Casoli and Andre-Nicolas Chene and Nicole St-Louis of the Universite de Montreal used measurements from the European Southern Observatory's Very Large Telescope in Chile, and infrared images from the Hubble Space Telescope to refine estimates of the two giant stars' masses. </p> <p class="MsoNormal">By measuring how the stars orbit around each other, the researchers were able to calculate each one's mass, though the level of uncertainty is still quite high (the larger weighs 116 plus-or-minus 30 solar masses, while the smaller weighs 89 plus-or-minus 15 solar masses). The astronomers hope to refine these calculations even further with future observations.</p> <p class="MsoNormal">The heavyweight binary, called A1, is in the star cluster NGC 3603, which lies in the Carina spiral arm of the Milky Way, around 20,000 light-years away from our solar system.</p> <p class="MsoNormal">The two A1 stars are thought be "Wolf-Rayet" stars, which are very hot, heavy and evolved stars that appear to be losing a large amount of mass in a stellar wind, similar to our sun's solar wind, but stronger. These stars are so large and luminous that the pressure of their outward-pouring radiation outweighs the inward pull of their gravity, so material is constantly being blown away into space.</p> <p class="MsoNormal">These stars can lose a significant portion of their mass &mdash; ten of percent of their total bulk &mdash; to this process over their lifetimes. The more massive a star is, the shorter its lifetime, since it tends to burn through itself quicker. These very huge stars only live for 2 to 3 million years before dying in supernovae explosions.</p> <p class="MsoNormal">Now that the researchers have found that the massive stars in A1 are Wolf-Rayet stars, it may help them locate similar finds.</p> <p class="MsoNormal">"We're on to something new, that the most massive stars are probably like this," Moffat told SPACE.com "This is a new revelation, I think. We should look for Wolf-Rayet stars like this."</p> <p class="MsoNormal">Confirming the mass of these gigantors is important because theories of star formation predict the existence of extremely massive stars weighing up to 150 times the mass of our sun. Besides these two, though, no other stars yet discovered have come close to that upper range.</p> <p class="MsoNormal">The same research team previously announced the discovery of this system in 2007, but the research had not been published yet in a peer-reviewed journal. In the meantime, they have further refined the measurements, and have recently detailed their findings in the September 2008 issue of the journal <em>Monthly Notices of the Royal Astronomical Society</em>.</p><p class="MsoNormal">http://www.space.com/scienceastronomy/080919-massive-star.html</p></div></font></font>&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[UFmbutler]

<p>That's a really cool story.&nbsp; Massive stars are very strange.&nbsp; I don't study them directly, but a lot of my work deals with looking at the initial conditions under which most massive stars and star clusters form.&nbsp; They are believed to form in clouds such as these</p><p>

</p><p>This is a cloud about 5 kpc away, toward the galactic center.&nbsp; There are tons of these things in the galaxy and are the dense cores of GMCs.&nbsp; This one has a mass of about 50,000 solar masses, and many protostars have been identified from molecular data in clouds like this.&nbsp; As you can see from the image it is a fairly turbulent process...we hope to be able to say something about huge stars like this by studying the more turbulent clouds. &nbsp;</p><p>This doesn't really have anything to do with these particular stars but I thought it might be interesting to see where these form. </p> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That's a really cool story.&nbsp; Massive stars are very strange.&nbsp; I don't study them directly, but a lot of my work deals with looking at the initial conditions under which most massive stars and star clusters form.&nbsp; They are believed to form in clouds such as these

This is a cloud about 5 kpc away, toward the galactic center.&nbsp; There are tons of these things in the galaxy and are the dense cores of GMCs.&nbsp; This one has a mass of about 50,000 solar masses, and many protostars have been identified from molecular data in clouds like this.&nbsp; As you can see from the image it is a fairly turbulent process...we hope to be able to say something about huge stars like this by studying the more turbulent clouds. &nbsp;This doesn't really have anything to do with these particular stars but I thought it might be interesting to see where these form. <br />Posted by UFmbutler</DIV><br /><br />Sorry to be dense (haha) but GMC's? It's not on my secret decoder ring. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Sorry to be dense (haha) but GMC's? It's not on my secret decoder ring. <br /> Posted by MeteorWayne</DIV></p><p>Giant molecular clouds.</p><p>&nbsp;</p><p>(nice pun <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" />) </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That's a really cool story.&nbsp; Massive stars are very strange.&nbsp; I don't study them directly, but a lot of my work deals with looking at the initial conditions under which most massive stars and star clusters form.&nbsp; They are believed to form in clouds such as these

This is a cloud about 5 kpc away, toward the galactic center.&nbsp; There are tons of these things in the galaxy and are the dense cores of GMCs.&nbsp; This one has a mass of about 50,000 solar masses, and many protostars have been identified from molecular data in clouds like this.&nbsp; As you can see from the image it is a fairly turbulent process...we hope to be able to say something about huge stars like this by studying the more turbulent clouds. &nbsp;This doesn't really have anything to do with these particular stars but I thought it might be interesting to see where these form. <br /> Posted by UFmbutler</DIV></p><p>I always find it amazing how massive these structures are, yet (in most cases) you can see right through them (especially the closer you get).&nbsp; Gives perspective on how spatially large they are.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Giant molecular clouds.&nbsp;(nice pun ) <br />Posted by derekmcd</DIV><br /><br />I should've known that. Tnx <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Giant molecular clouds.&nbsp;(nice pun ) <br />Posted by derekmcd</DIV></p><p><br />&nbsp;I thought they were high-end Chevrolets. </p> <div class="Discussion_UserSignature"> </div>

 

[Philotas]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>[...]<br />Posted by derekmcd</DIV></p><p>The massive one burns out first, blows up as a hypernova, becomes a black hole and gets a nice accretion disc consisting of&nbsp;gas sucked of its massive companion star, no?</p> <div class="Discussion_UserSignature"> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The massive one burns out first, blows up as a hypernova, becomes a black hole and gets a nice accretion disc consisting of&nbsp;gas sucked of its massive companion star, no? <br /> Posted by Philotas</DIV></p><p>Here's the relevant paper, thought it doesn't discuss the evolution of the binary.<br /><br />http://arxiv.org/pdf/0806.2815<br /><br />I notice that they have a rotation period of 3.77 days.&nbsp; That's mighty close (close enough... I don't know).&nbsp; With them both being Wolf-Rayet stars shedding large amount of mass, I imagine they are already exchanging some material (assuming the material can get past the stellar winds and into the Roche Lobe limit of the more massive star). <br /><br />It would seem logical that the more massive of the two would go supernova first, but that's with the assumption they both formed at nearly the same time.&nbsp; No real guarantees there, though gravitational capture doesn't seem very likely as young and massive as they are.&nbsp; It's also possible (but in this case, probably not likely) they could merge first.&nbsp; <br /><br />What an event that would turn out to be!!!<br /><br />Most likely, the more massive of the two will result in a type II supernova that theoretically ends up as a black hole.&nbsp; What happens to its companion star?&nbsp; I don't know.&nbsp; The supernova from the primary star could blow away enough material from its companion, that it no longer has enough gravitational pressure to hold itself together.&nbsp; In other words, the first supernova simply destroys the companion star.<br /><br />If it doesn't blow away enough material from it's companion, we could potentially end up with a 2nd type II supernova that, depending on the remaining mass of the progenitor, would result in a black hole or neutron star.&nbsp; Then we end up with binary stellar remnants that may merge or kick each other out of orbit.<br /><br />If neither happens, it would do as you say.&nbsp; A black hole with a mighty accretion disk and spectacular relativistic polar jets would occur.<br /><br />Pretty interesting stuff... </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[Philotas]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Here's the relevant paper, thought it doesn't discuss the evolution of the binary.http://arxiv.org/pdf/0806.2815I notice that they have a rotation period of 3.77 days.&nbsp; That's mighty close (close enough... I don't know).&nbsp; With them both being Wolf-Rayet stars shedding large amount of mass, I imagine they are already exchanging some material (assuming the material can get past the stellar winds and into the Roche Lobe limit of the more massive star). It would seem logical that the more massive of the two would go supernova first, but that's with the assumption they both formed at nearly the same time.&nbsp; No real guarantees there, though gravitational capture doesn't seem very likely as young and massive as they are.&nbsp; It's also possible (but in this case, probably not likely) they could merge first.&nbsp; What an event that would turn out to be!!!Most likely, the more massive of the two will result in a type II supernova that theoretically ends up as a black hole.&nbsp; What happens to its companion star?&nbsp; I don't know.&nbsp; The supernova from the primary star could blow away enough material from its companion, that it no longer has enough gravitational pressure to hold itself together.&nbsp; In other words, the first supernova simply destroys the companion star.If it doesn't blow away enough material from it's companion, we could potentially end up with a 2nd type II supernova that, depending on the remaining mass of the progenitor, would result in a black hole or neutron star.&nbsp; Then we end up with binary stellar remnants that may merge or kick each other out of orbit.If neither happens, it would do as you say.&nbsp; A black hole with a mighty accretion disk and spectacular relativistic polar jets would occur.Pretty interesting stuff... <br />Posted by derekmcd</DIV></p><p>&nbsp;Good post. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /><br /></p> <div class="Discussion_UserSignature"> </div>