Supernova in the air?

[alokmohan]

http://news.bbc.co.uk/2/hi/science/nature/5204676.stm.ARE WE GOING TO SEE SUPERNOVA SOON?

 

[tom_hobbes]

Corrected URL:<br /><br /><br />http://news.bbc.co.uk/1/hi/sci/tech/5204676.stm <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[nova_explored]

that would be remarkable, if so. <div class="Discussion_UserSignature"> </div>

 

[docm]

Maybe tomorrow, maybe much longer;<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>But soon, RS Oph could pass the tipping point - the nuclear flame will detonate from deep inside the star and blow it apart. How soon is not clear.<br /><br />"It could be tomorrow, but most likely it'll be 1,000, 10,000, 100,000 years from now," says Jeno Sokoloski.<br /><br />Whenever it happens, it will be, she says, a spectacular event, outshining the planets, so that its final glory will be visible against the day time sky.<br /><br />In the meantime, astronomers will be studying the star closely, to watch its every step towards destruction, and hoping to understand the full details of one of the heaven's great mysteries. <p><hr /></p></p></blockquote> <div class="Discussion_UserSignature"> </div>

 

[leopold]

From http://www.cnn.com/2006/TECH/space/07/20/explosive.star/:<br /><br />"The white dwarf in RS Ophiuchi is near this critical limit now, but it will still probably need hundreds of thousands of years to accumulate the final bit of mass[...]"<br /><br />No Ophiuchi light show within our lifetimes, unfortunately... <img src="/images/icons/frown.gif" /> A better bet for that would be Betelgeuse. From Wikipedia and http://www.sunshinedna.com/?p=4 , it'll go supernova sometime within the next thousand years.

 

[doubletruncation]

If you're interested you can see the paper on RS Oph at:<br />http://xxx.lanl.gov/abs/astro-ph/0605326<br /><br />as best I can tell, they determine the mass of the white dwarf by measuring the mass of the ejecta shell (about 1E-7 solar masses), they compare this to a theoretical model of white dwarf novae that was calculated for a 1.25 solar mass white dwarf and a 1.4 solar mass white dwarf. The 1.25 solar mass white dwarf would eject about 1E-6 solar masses whereas the 1.4 solar mass white dwarf would eject about 2E-7 solar masses. So they conclude that the white dwarf is very close to 1.4 solar masses which is the magic number for which it would explode. But it's not clear exactly how close it is to that mass (for one thing, it's never clear how good theoretical models like this are) so it's not clear exactly what the mass of the white dwarf is (I also have no idea how good an estimate there is for the mass accretion, though I would guess that it isn't incredibly precise beyond at least one significant digit). I think the point is that for all we know this star could go Type Ia supernova tomorrow, the hundreds of thousands of years may be an upper limit on the time when it will happen.<br /><br />For Betelgeuse, I think again we don't necessarily understand the atmospheres and evolution of stars that massive well enough to say exactly when the thing is going to go off (I would think a 1000 years is probably too precise an estimate). For one thing it was recently discovered that these stars are actually much cooler than we previously thought, mass-loss rates etc and how these affect the star's evolution are not very well determined either, and we don't even know Betelgeuse's mass that precisely (see for example: http://www.solstation.com/x-objects/betelgeuse.htm ).<br /><br />Also note that until last year the only supernov <div class="Discussion_UserSignature"> </div>

 

[qso1]

docm:<br />Maybe tomorrow, maybe much longer;<br /><br />Me:<br />This is also the case with Betelgeuse and Eta Carinae. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>