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Supernova May Wipe Out Earth... Someday
Halster writes "And it could take our planet with it. Reported in the New Scientist. Harvard student Karin Sandstrom discovered the star while researching a paper. It's named HR 8210, and is a white dwarf about 150 light years from our planet, that's 10 light years short of the 160 to 200 theoretical light years thought to be a safe distance from a SuperNova. Left alone it won't turn SuperNova, but it's parked next to another Sun that will "Very soon" turn into a red giant star and expand lending mass to the HR 8210 which will then push HR 8210 over the edge and go SuperNova on us. Course "Very soon" to an astronomer is hundreds of millions of years. And by that time the two stars will likely have moved away from the earth. So don't jump into your escape pod yet." Update: 05/23 20:16 GMT by M : Heh. It seems New Scientist didn't get the story quite right. :) Read the correction below.
Hi,
I'm Karin, the one quoted in this article as having discovered the supernova progenitor. I just wanted to let you all know to pay very little attention to the article. The reporter has taken one fact: that this might be a good candidate for a Type Ia supernova, and constructed a big mess out of it. I am very embarassed by this so I just wanted to clear up a few things.
First, I did NOTHING in the discovery process. I was just writing my senior thesis on white dwarfs and happened to study this system. It was discovered in 1993 by two separate groups of scientists (Landsman et al 1993, and Wonnacott et al 1993) They found the mass to be 1.15 solar masses, which is relatively large for a white dwarf star, but not the "just shy" of the Chandrasekhar limit that the reporter says. It is 0.3 times the mass of the sun shy of the limit, and that is a lot of mass. Lots and lots of people have studied this system since then, and many have commented on its possibilities for a supernova. All that I did in this story is to mention the system to a scientist here at Harvard who happens to simulate the evolution of a binary system towards a supernova and then mention in in a public talk about my thesis when a New Scientist reporter happened to be in the audience. The reporter got very excited and wrote this article, and left out the actual work that is being done on the evolutionary scenarios to sensationalize the possibility of a near earth supernova.
Second, what we have found, if anything, is that by the time that the white dwarf star has accreted enough mass from its companion to exceed the Chandrasekhar limit of 1.4 solar masses, it will be at least 10 kiloparsecs from earth, which is well on its way to the other side of the galaxy. The star will not pose any threat at all to earth. This is also hundreds of millions to billions of years in the future.
I think the interesting part of this story is the terrible state of scientific news reporting in some popular journals. We discussed these problems extensively with the reporter and they were completely disregarded in the final version. Be on the lookout for our letter to the editor if you are interested.
If anyone would like to know more about this, I'd be happy to explain what we really think is going on...unless you are a reporter, in which case don't bother...I'm done with them.
Thanks,
Karin Sandstrom