are there any supernova candidates near earth that could harm us?

[izzywizzy]

<p>Are there any supernova candidates near earth that could harm us in our lifetimes?&nbsp; </p><p>(such as a type II or a white dwarf exploding from taking matter from another star...etc)</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p>

 

[neilsox]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Are there any supernova candidates near earth that could harm us?&nbsp; (such as a type II or a white dwarf exploding from taking matter from another star...etc)&nbsp;&nbsp;&nbsp; <br />Posted by izzywizzy</DIV><br />Several could dangerously increase radiation exposure for the astronaughts in the ISS = international space station or the space shuttle, but the radiation dose on Earth's surface would be negligible due to the protection by Earth's atmosphere and magnetic field. Millions of years from now, some of the near by stars will be different, so we could have a disaster in the far future.&nbsp; Neil

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Are there any supernova candidates near earth that could harm us in our lifetimes?&nbsp; (such as a type II or a white dwarf exploding from taking matter from another star...etc)&nbsp;&nbsp;&nbsp; <br /> Posted by izzywizzy</DIV></p><p>Our biggest concern with supernova would be from gamma ray bursts.&nbsp; This would require that the poles of the star be pointed directly at us.&nbsp; The only 2 that I can think of off the top of my head are Eta Carinae and Betelguese (sp?).&nbsp; Eta C's poles are definitely not pointed at us as you can see by the lobes it has ejected.&nbsp; If I recall correctly, neither is Betelguese's poles.</p><p>Type 1a supernova (white dwarfs exploding) don't produce gamma ray bursts (none that I can recall reading about anyway) and would need to be very close to us to affect us.&nbsp; Probably within a few 10's of light years and I don't believe there are any potentials that close.</p><p>As for gamma ray bursts happening?&nbsp; No need to really worry about them... by the time we see them, it will be too late to do anything about it.&nbsp; Not much, if anything, we can do to pre-emptively protect ourselves either.</p><p>I wouldn't fear.&nbsp; Definitely nothing in our lifetimes.&nbsp; It would, indeed, be a rare event for a supermassive star to be perfectly aligned with us and be close enough to do any damage.&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>

 

[izzywizzy]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Several could dangerously increase radiation exposure for the astronaughts in the ISS = international space station or the space shuttle, but the radiation dose on Earth's surface would be negligible due to the protection by Earth's atmosphere and magnetic field. Millions of years from now, some of the near by stars will be different, so we could have a disaster in the far future.&nbsp; Neil <br /> Posted by neilsox</DIV></p><p>what do you mean by "some of the near by stars will be different" &nbsp;&nbsp;</p><p>&nbsp;</p><p>how will they be different? </p>

 

[izzywizzy]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Our biggest concern with supernova would be from gamma ray bursts.&nbsp; This would require that the poles of the star be pointed directly at us.&nbsp; The only 2 that I can think of off the top of my head are Eta Carinae and Betelguese (sp?).&nbsp; Eta C's poles are definitely not pointed at us as you can see by the lobes it has ejected.&nbsp; If I recall correctly, neither is Betelguese's poles.Type 1a supernova (white dwarfs exploding) don't produce gamma ray bursts (none that I can recall reading about anyway) and would need to be very close to us to affect us.&nbsp; Probably within a few 10's of light years and I don't believe there are any potentials that close.As for gamma ray bursts happening?&nbsp; No need to really worry about them... by the time we see them, it will be too late to do anything about it.&nbsp; Not much, if anything, we can do to pre-emptively protect ourselves either.I wouldn't fear.&nbsp; Definitely nothing in our lifetimes.&nbsp; It would, indeed, be a rare event for a supermassive star to be perfectly aligned with us and be close enough to do any damage.&nbsp; <br /> Posted by derekmcd</DIV></p><p>i see,</p><p>thanks </p><p>&nbsp;</p>

 

[vincentm]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>what do you mean by "some of the near by stars will be different" &nbsp;&nbsp;&nbsp;how will they be different? <br /> Posted by izzywizzy</DIV></p><p>Stars within a 10lyr radius might have a fate that can affect earth.&nbsp; </p> <div class="Discussion_UserSignature"> <p>----------------------------------</p><p><br /><img id="2645f485-13bb-45be-ba60-5bfc5dfaa2a0" src="http://sitelife.space.com/ver1.0/Content/images/store/6/10/2645f485-13bb-45be-ba60-5bfc5dfaa2a0.Large.png" alt="blog post photo" width="237" height="95" /><br /> </p> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Stars within a 10lyr radius might have a fate that can affect earth.&nbsp; <br />Posted by vincentm</DIV><br /><br />Like which ones? There are only a handful within 10 LY and AFAIK, none of them can ever be a threat <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>

 

[silylene old]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Like which ones? There are only a handful within 10 LY and AFAIK, none of them can ever be a threat <br />Posted by MeteorWayne</DIV><br /><br />GRB's (gamma ray bursters) are probably a bigger threat than supernovas to earth anyways.</p><p>Vega is perhaps(?) the scariest candidate.&nbsp; Its pole points directly at earth, and it is hyper-rotating, and has an accretion disc.&nbsp; I first pointed out this potential danger to earth in a post in 2006, after reading a journal article in <em>Nature</em>.</p><p>If the pole is pointing directly at us, a beam of focussed radiation would be emitted in these directions in certain scenarios.&nbsp; We&nbsp;had a great&nbsp;thread on this subject in the good ole Pre-Pluck SDC forums: http://uplink.space.com/showflat.php?Cat=&Board=sciastro&Number=716233&page=27&view=collapsed&sb=5&o=0&fpart=1&vc=1&nbsp; .</p><p>&nbsp;</p><p>Here is my post from that forum, since most people can't access it anymore:</p><p>DISCLAIMER: I have no knowledge that Vega would every become a GRB or a nova. Please don't get overexcited, and let me indulge in some speculation. <br /><br />What we know, and my speculation..... <br />Vega is a type A01 star 25 light years away with a mass 2.3x the sun, and about 500M years old. It is very rapidly rotating, so its shape is an oblate spheroid. In fact, it rotates so fast it is very close (93%) to the rotation speed which would cause disruption due to centrifugal effects. Vega is known to be surrounded by a disc of dust, presumed rocks, and perhaps planets which are slowly infalling. <br /><br />OK, so what makes Vega interesting? <font color="#ff0000">Vega's polar rotational axis is coincidently<em> aimed directly at the earth</em></font>. I read about this last month in an interesting article in the journal <em>Nature</em>, and immediately thought...what if some inflalling planet or planettoid broke apart and fell into Vega? Couldn't that cause a huge jet of plasma to be ejected right at the Earth? <br /><br />The <em>Nature</em> article doesn't claim this happened, it just describes recent research on this very interesting and close star. It is entirely my speculation that Vega could be the smoking gun. I am curious what others think. If this is absurd, my apologies, I do not have deep knowledge of the mechanisms which can cause huge polar jet emissions and bursts from stars. </p><p>&nbsp;</p><p>http://en.wikipedia.org/wiki/Vega</p> <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Like which ones? There are only a handful within 10 LY and AFAIK, none of them can ever be a threat <br /> Posted by MeteorWayne</DIV></p><p>Here's a list of the top 10 closest stars.&nbsp; Only 9 of them are within 10 ly and none of them are remotely massive enough for a type II supernova.&nbsp; The only one that might concern me is the Centauri system, but I don't believe the binary system would be capable of producing a type 1A supernova.&nbsp; The combination of the two simply don't have enough mass to feed a white dwarf beyond the required mass needed to start collapsing which heats it up to sufficient temps which reignite the fusion process.</p><p>http://space.about.com/od/stars/tp/closeststars.htm</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]

I can't think of any mechanism for Vega to produce enough energy to threaten us.<br /> <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>

 

[silylene old]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I can't think of any mechanism for Vega to produce enough energy to threaten us. <br />Posted by derekmcd</DIV><br /><br />Please read the pre-Pluck thread for information.&nbsp; Link was in my post above. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Please read the pre-Pluck thread for information.&nbsp; Link was in my post above. <br /> Posted by silylene</DIV></p><p>I reread that thread to make sure I didn't miss anything.&nbsp; I also participated a bit in that thread.&nbsp; Not quite sure what I'm supposed to be looking for.</p><p>Vega, although impressive with its rotation, simply can't produce an accretion disk with enough energy to create x-ray jets, much less gamma-ray jets.&nbsp; Any infalling matter wouldn't get hot enough to produce electromagnetic radiation strong enough to affect us.&nbsp; The matter in the accretion disk is literally converted to energy.&nbsp; It's how they shed the angular momentum. </p><p>With black holes and neutron stars, the accretion disks are accelerated to relativistics speed in order to produce x-ray jets.&nbsp; As far as I know, gamma ray bursts are only seen in type II supernovae and colliding black holes and neutron stars.&nbsp; Anything less isn't a matter of concern to us (afaik).&nbsp; </p><p>You would also need a copious amount of infalling matter to have any real effect.&nbsp; I'm guessing here, but If you took all the matter in Vega's system and turned it into an accretion disk, It would likely be fairly diffuse and produce jets in the infrared spectrum.</p><p>Even as a proto-star or T Tauri star when Vega was forming, I doubt any outflows from the poles would have been energetic enough to produce anything beyond infrared raditation.&nbsp;</p><p>It's all probably a moot point anyway as the axis may not be quite directly pointed at us.&nbsp;</p><p><strong>http://arxiv.org/abs/astro-ph/0603327v1</strong></p><p>Clip from abstract:</p><p><strong><em>Our best fitting model indicates that Vega is rotating at ~91% of its angular break-up rate with an equatorial velocity of 275 km/s. Together with the measured vsin(i), this velocity yields an inclination for the rotation axis of 5 degrees.</em></strong></p><p>I'm not sure if 5 degrees is enough to miss us or not, or if Vega's precession crosses our path.&nbsp;</p><p>&nbsp;</p><p>&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>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>... Together with the measured vsin(i), this velocity yields an inclination for the rotation axis of 5 degrees.I'm not sure if 5 degrees is enough to miss us or not, or if Vega's precession crosses our path.&nbsp;&nbsp;&nbsp; <br />Posted by derekmcd</DIV></p><p>That is my question.&nbsp; If one assume that Vega burps something, then how directionally tight is the burp ?&nbsp; If it were a rifle being fired at 100 yds., a 5 degree pointing error would result in a miss of about 26 feet.&nbsp; I would feel pretty comfortable with that (not comfortable enough to stand in front of the target though).&nbsp; But when a star throws out stuff from the pole, how tight is the "beam"?<br /></p> <div class="Discussion_UserSignature"> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That is my question.&nbsp; If one assume that Vega burps something, then how directionally tight is the burp ?&nbsp; If it were a rifle being fired at 100 yds., a 5 degree pointing error would result in a miss of about 26 feet.&nbsp; I would feel pretty comfortable with that (not comfortable enough to stand in front of the target though).&nbsp; But when a star throws out stuff from the pole, how tight is the "beam"? <br /> Posted by DrRocket</DIV></p><p>Good question.&nbsp; I'm sure there's quite a few factors when considering the energy, focus and divergence of the jet.&nbsp; In the case of a star like Vega, the energies will be low, but I wouldn't know where to begin on figuring out how it would be focused and how extreme the divergence would be.&nbsp; Considering the outflow of matter would be quite slow (compared to x-ray jets), I would guess the the focus would be weak and the divergence be large enough for us to not to worry.&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]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Good question.&nbsp; I'm sure there's quite a few factors when considering the energy, focus and divergence of the jet.&nbsp; In the case of a star like Vega, the energies will be low, but I wouldn't know where to begin on figuring out how it would be focused and how extreme the divergence would be.&nbsp; Considering the outflow of matter would be quite slow (compared to x-ray jets), I would guess the the focus would be weak and the divergence be large enough for us to not to worry.&nbsp; <br />Posted by derekmcd</DIV></p><p>I'll keep a close eye on Vega tonight when I'm out playing with meteors. It's hard not to, it's almost straight overhead!</p> <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'>I'll keep a close eye on Vega tonight when I'm out playing with meteors. It's hard not to, it's almost straight overhead! <br />Posted by MeteorWayne</DIV></p><p>Wear safety glasses. so you don't get something in your eye. <br /></p> <div class="Discussion_UserSignature"> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Good question.&nbsp; I'm sure there's quite a few factors when considering the energy, focus and divergence of the jet.&nbsp; In the case of a star like Vega, the energies will be low, but I wouldn't know where to begin on figuring out how it would be focused and how extreme the divergence would be.&nbsp; Considering the outflow of matter would be quite slow (compared to x-ray jets), I would guess the the focus would be weak and the divergence be large enough for us to not to worry.&nbsp; <br />Posted by derekmcd</DIV></p><p>This (Eta Carinae)is probably not a good model for Vega.&nbsp;&nbsp;The ejecta does not appear to be very precisely collimated -- I'd eyeball it at maybe a 45 degree spread.&nbsp; <br /><br /><img src="http://imgsrc.hubblesite.org/hu/db/1996/23/images/a/formats/small_web.jpg" alt="" /></p><p>But this one seems more laser-like</p><p><img src="http://imgsrc.hubblesite.org/hu/db/1999/05/images/k/formats/small_web.jpg" alt="DG Tauri B: A Star With a Thick Dust Lane and Bright Gas Jet" width="200" height="200" /></p> <div class="Discussion_UserSignature"> </div>

 

[vincentm]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Like which ones? There are only a handful within 10 LY and AFAIK, none of them can ever be a threat <br /> Posted by MeteorWayne</DIV></p><p>I didn't clarify (my apologies), i meant to stay Stars within10-30lyr radius MIGHT, Although i don't we'll be experiencing any of this in our lifetimes.&nbsp; </p> <div class="Discussion_UserSignature"> <p>----------------------------------</p><p><br /><img id="2645f485-13bb-45be-ba60-5bfc5dfaa2a0" src="http://sitelife.space.com/ver1.0/Content/images/store/6/10/2645f485-13bb-45be-ba60-5bfc5dfaa2a0.Large.png" alt="blog post photo" width="237" height="95" /><br /> </p> </div>

 

[izzywizzy]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I didn't clarify (my apologies), i meant to stay Stars within10-30lyr radius MIGHT, Although i don't we'll be experiencing any of this in our lifetimes.&nbsp; <br /> Posted by vincentm</DIV></p><p>&nbsp;i know we won't be experiencing any in our lifetimes, but im wondering which stars specifically would move that close to us in a few million years that also could explode? </p>

 

[izzywizzy]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>GRB's (gamma ray bursters) are probably a bigger threat than supernovas to earth anyways.Vega is perhaps(?) the scariest candidate.&nbsp; Its pole points directly at earth, and it is hyper-rotating, and has an accretion disc.&nbsp; I first pointed out this potential danger to earth in a post in 2006, after reading a journal article in Nature.If the pole is pointing directly at us, a beam of focussed radiation would be emitted in these directions in certain scenarios.&nbsp; We&nbsp;had a great&nbsp;thread on this subject in the good ole Pre-Pluck SDC forums: http://uplink.space.com/showflat.php?Cat=&Board=sciastro&Number=716233&page=27&view=collapsed&sb=5&o=0&fpart=1&vc=1 .&nbsp;Here is my post from that forum, since most people can't access it anymoreISCLAIMER: I have no knowledge that Vega would every become a GRB or a nova. Please don't get overexcited, and let me indulge in some speculation. What we know, and my speculation..... Vega is a type A01 star 25 light years away with a mass 2.3x the sun, and about 500M years old. It is very rapidly rotating, so its shape is an oblate spheroid. In fact, it rotates so fast it is very close (93%) to the rotation speed which would cause disruption due to centrifugal effects. Vega is known to be surrounded by a disc of dust, presumed rocks, and perhaps planets which are slowly infalling. OK, so what makes Vega interesting? Vega's polar rotational axis is coincidently aimed directly at the earth. I read about this last month in an interesting article in the journal Nature, and immediately thought...what if some inflalling planet or planettoid broke apart and fell into Vega? Couldn't that cause a huge jet of plasma to be ejected right at the Earth? The Nature article doesn't claim this happened, it just describes recent research on this very interesting and close star. It is entirely my speculation that Vega could be the smoking gun. I am curious what others think. If this is absurd, my apologies, I do not have deep knowledge of the mechanisms which can cause huge polar jet emissions and bursts from stars. &nbsp;http://en.wikipedia.org/wiki/Vega <br /> Posted by silylene</DIV></p><p>&nbsp;</p><p>I thought vega is going to turn into&nbsp; white dwarf. And i thought GRB's are uncommon in metal rich galaxies like ours.</p><p>And its not pointed directly at us, it's 5 degrees off. </p>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>This (Eta Carinae)is probably not a good model for Vega.&nbsp;&nbsp;The ejecta does not appear to be very precisely collimated -- I'd eyeball it at maybe a 45 degree spread.&nbsp; But this one seems more laser-like <br /> Posted by DrRocket</DIV></p><p>The lower image you provided is of DG Tau B, a T-Tauri star, imaged by Hubble using its wide field planetary camera.&nbsp; This camera takes images in the range of near infrared to near ultraviolet.</p><p>http://www.astro.caltech.edu/~sed/star_formation.html</p><p>I have take back my statement earlier about t-tauri stars and the types of outflows they produce.&nbsp; Apparently they can produce x-ray jets, but it would appear that they are quite weak and don't extend very far.</p><p>Here's an image of DG Tau as seen by the chandra x-ray observatory:</p><p>http://chandra.harvard.edu/photo/2008/dgtau/index.html&nbsp;</p><p><br /> <img src="http://sitelife.space.com/ver1.0/Content/images/store/10/5/da5435b8-c3f9-4a3f-858e-1fae71f2b080.Medium.jpg" alt="" /><br />(The left is obviously the real image and the right is an illustration)</p><p>This arxiv paper concerns such stars and their jets (including DG Tau B)</p><p>http://arxiv.org/pdf/astro-ph/0404016</p><p>In it, they offer distances of up to ~1.4 parsecs (about 4.5 ly).</p><p>Obvously, that distance still isn't nearly enough for Vega to have affected us when it was pre-main sequence.&nbsp; Given the uniqueness of Vega with it's rapid rotation, it might be logical to conclude that it may have had more mass when it was forming throwing off a lot of material.&nbsp; This rotation might have been enough to accelerate material in it's accretion disk to high enough speeds to create an x-ray jet to have possibly affected Earth.&nbsp; I highly doubt it, but I'm no expert and my doubts equal precisely jack. </p><p>&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>

 

[eburacum45]

Stars like Vega are&nbsp;quite common. None have been observed to emit collimated beams- so I won't be losing any sleep about it. <div class="Discussion_UserSignature"> <p>---------------------------------------------------------------</p><p>http://orionsarm.com  http://thestarlark.blogspot.com/</p> </div>