question about type 1a supernovae

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izzywizzy

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My question is how far away generally speaking do you have to be from a 1a supernova to be considered a safe distance.<p>&nbsp;so i read this on wikipedia...<br /> </p><p>"One theory suggests that a Type&nbsp;Ia supernova would have to be closer than a thousand parsecs (3300&nbsp;light-years) to affect the Earth."</p><p>&nbsp;</p><p>Some of the answers i've gotten are ..</p><p>-100 light years away to not have any noticable effects</p><p>- around 30 ly away</p><p>-500 light years (read that on another page in wikipedia)</p><p>&nbsp;</p><p>So I'm just wondering if anyone knows the real answer lol. </p>
 
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weeman

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>My question is how far away generally speaking do you have to be from a 1a supernova to be considered a safe distance.&nbsp;so i read this on wikipedia... "One theory suggests that a Type&nbsp;Ia supernova would have to be closer than a thousand parsecs (3300&nbsp;light-years) to affect the Earth."&nbsp;Some of the answers i've gotten are ..-100 light years away to not have any noticable effects- around 30 ly away-500 light years (read that on another page in wikipedia)&nbsp;So I'm just wondering if anyone knows the real answer lol. <br />Posted by izzywizzy</DIV><br /><br />I'm no expert. All I know is one of the best supernova candidates on our side of the galaxy right now is Eta Carinae, which sits about 8,000 LY from Earth. Eta suffered a massive erruption some 150 years ago, but the star survived this burst, and has not actually gone supernova. Yet it will go violently when it does, considering it's about 100 solar masses and&nbsp;is one of the most massive stars discovered in our galaxy!&nbsp;It's pressumed that it will go supernova sometime within the next million years. From what I've gathered, if Eta went supernova within our lifetimes, it would&nbsp;pose no&nbsp;major threat to life on Earth. Of course, with other supernovae, it depends greatly on the size of the event, and the amount of gamma radiation that is released. </p><p>The largest number you found was 500 LY away. I'd say type 1a's could affect as from a much farther distance than 500 LY. A distance of 500 LY is just a stone's throw away on a galactic scale! </p><p>Again, I'm not an astrophysicist, just an astronomy enthusiast. I'd wait for a response from one of the scientists on this board <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" />&nbsp;</p><p>This is a shout out to MeteorWayne, where ever he's at! </p> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>
 
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eburacum45

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<p>The best source I have seen so far is this one: &nbsp;Will a Nearby Supernova Endanger Life on Earth? by&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Michael Richmond<br />http://www.tass-survey.org/richmond/answers/snrisks.txt</p><p>and from ther you will find this&nbsp;quote</p><p>&nbsp; Neil Gehrels et al. calculate the effect of gamma rays from <br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; a nearby supernova on the ozone layer of the Earth.&nbsp; The preprint<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; is http://xxx.lanl.gov/abs/astro-ph/0211361, and the paper<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; is published in vol 585 of Astrophysical Journal.&nbsp; They<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; conclude that a Type Ia SN would have to be within about <br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 8 parcsecs of the Earth to destroy half the ozone layer,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; and therefore have a significant effect on the biosphere.<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; You can read a press release at <br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; http://www.sciencedaily.com//releases/2003/01/030122072843.htm</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p>---------------------------------------------------------------</p><p>http://orionsarm.com  http://thestarlark.blogspot.com/</p> </div>
 
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derekmcd

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<p>&nbsp;</p><p>I've read that paper through arxiv and it is about supernova 1987a which was a type II supernova.&nbsp; Why the statement is reading a type Ia at being 8 pc (about 26 light years) is beyond me.&nbsp; Maybe a typo?&nbsp; Hard to say... i've seen many articles that attribute data from type II supernova to all supernova in general.</p><p>I don't think you are going to find an adequate answer about type Ia supernovae.&nbsp; They are just to rare to have been able to adequately study.&nbsp; Most of what you will find is speculation as seen in that tass-survey paper which seems to be quoted often due to its placement in Wiki.&nbsp; I doubt you will find a single peer reviewed paper to back up the 3300 ly number.&nbsp; Just not enough known about them except through computer simulations.</p><p>I've seen both numbers applies to both types of supernova.&nbsp; I wish I had a better answer for you.&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>
 
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eburacum45

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<p>From Richmond's essay, Type 1a supernovae are about a hundred times as powerful in gamma+X-rays as type&nbsp;II supernovae; because of the inverse square law that works out as a dangerous distance of ten times as far, or maybe around 260 light years.</p><p>&nbsp;But I have introduced too many approximations into the mix, so the dangerous distance for a Class 1a might be as much as 500 light years, or much less.</p> <div class="Discussion_UserSignature"> <p>---------------------------------------------------------------</p><p>http://orionsarm.com  http://thestarlark.blogspot.com/</p> </div>
 
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