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Space Science

Supernova May Wipe Out Earth... Someday 40

Posted by michael from the spf-15000 dept.
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.
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Supernova May Wipe Out Earth... Someday More

Supernova May Wipe Out Earth... Someday

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  • I'm not a rocket scientist, but one would think that if we dont actually go outside we would be unaffected by the lack of an ozone layer.
    Or if we do need to go outside, we would be unaffected if we wore protective clothing.
    If this really happened to us, I can see the vast majority of wildlife being bombarded by radiation.
    But what if we grew all our plants in greenhouses with high-tech sun filters, or even grow them indoors under artificial lighting?
    Then we could feed them to cows, chicken, etc.
    We could very well extend the subway system and travel exclusively underground, board up all the windows (grin), and coat our buildings with some sort of shielding.
    It would be hard to do this for absolutely everyone, but hey even if it blew up today it would take over a century for anything to get here.We have millions of years. Should we really worry?
    • NASA and other agencies we rely on for future
      space travel have lost control.

      They use the same propellant rocket, cosmic ray
      sails, tethered earth elevators, 100 billion watt
      stationary laser for light propulsion.

      One inventor who is serious about science
      was totally insulted by NASA saying let our
      scientist throw HOLY WATER on it, What they ment
      to say is "we hope to steal your idea and make it
      our own if we like it".

      Well he doesnt propose using gravitational fields using magnetic plasma, warp fields, folding time machines, matter transfer units, space time continum warp holes, but has found a solid physics application to space propulsion.

      Unfortunately this technologist has been ripped
      off many times and his ideas stolen and claimed by others that he will now not disclose this technology which he says makes present space
      technology obsolete.


  • Astronomer (giving a lecture in a planetarium): "And in about 2 billion years, the sun will exhaust its fuel supply and explode, consuming the earth and all the planets."
    Woman in audience: "Excuse me, did you say 2 billion years?"
    Astronomer: "Yes, 2 billion years."
    Woman: "Oh, what a relief! For a moment I thought you said '2 million years.'"

  • If the thing is 150 l-yrs away from us, that means everything we see about it is 150 years late, right ? So if it ever does explode, by the time we see it coming it will be too late already. Even if we were to launch some sort of defensive weapon or shield or whatnot, it would inevitably miss the target because it would be another 150 years late. Think long-distance phone lag, measured in years, not seconds.
    • Yeah, but we would see it as it happens, as the radiation/matter that would bombard can't possibly travel faster than light.
      Really, it would take 150 light years to reach us regardless. We would see as it made progress towards us.
      • A lot of that "radiation" is gamma rays (speed of light) and neutrinos (.9999999999 speed of light). The rest would be going only a paltry .99999 speed of light or so. So you might theoretically get a day or so of warning before the heavy particles hit. But even that is wrong, because you can't see alpha particles, protons and the like speeding towards you, they are too small to reflect enough light for that.
      • Unless the explosion actually happened 149 years ago ... Remember, we're seeing the star as it was 150 years ago, not as it is today. [1/2 g]
      • X-rays, gamma rays, microwaves, and plain old-fashioned heat all travel at the speed of light. This star, as has already been established, poses zero threat to earth. But if it did, we'd see the light from the supernova the same time the x-rays were frying us. We'd be dead, probably, before the actual matter from the star reached us.
      • what part of the "speed of light" dosen't fit there..
      • Do you understand what "see" means? Seeing is when light reaches your eyes. You cannot "see" light before it reaches your eyes. Where were you educated?
      • Like this.

        Matter/radiation/particles/etc. (traveling as fast as it can on it's best day)
        -----------> (EARTH)

        Light (The stuff we can see.)
        -----------> (EARTH)

        We would see it after it happened at the stars location, but we would see it as it happens from our relative point of view. Physical manifestation of the event would not arrive before we saw the thing. So if it already happened, we are not screwed until we actually see it happen. Then we all die.

        Perhaps I was foolish to use we to refer to Earth, rather than people. But, it's not like the star would just start spitting matter our way if it already happened, we would see symptoms of a supernova first, before damaging effects would hit us, as it doesn't start getting dangerous until later in its life cycle.

        And that's what I'm talking about. It's not like it will wipe us out and then an alien lands on the planet looks out and says "Hey there's a supernova forming 150 light years away!"

  • yes.. (Score:2, Insightful)

    by josepha48 ( 13953 )
    and I may go to the bathroom someday.. and an earthquake may make SF an island someday.. and an asteroid may hit the earth someday and wipe out all of humanity.. and .. and.. a black hole may swallow us up ... this is really nothing new.. I guess it is better than listening to the religion right tell us all that we are going to hell and that Jesus is coming to save only them...

    So many Christians so few lions...

  • As i remember from astronomy course, supernova is exploding star. Speed of that explosion frontier is near speed of light... Acvtually, it should be nuclear chain reaction, as stars are powered by nuclear power.

    And that means you can't kill explosion of supernova with nuclear weapons, and you can't make a shield strong enought as earth will be vaporized...

  • "Earth" != "our planet" ??? (Score:4, Funny)

    by Goronguer ( 223202 ) on Thursday May 23, 2002 @02:16PM (#3574067)

    Supernova May Wipe Out Earth... Someday

    And it could take our planet with it.

    Err... am I missing some key distinction here? Last I checked, "Earth" and "our planet" were one and the same.

  • New Scientist Article (Score:5, Informative)

    by Karinms ( 581210 ) on Thursday May 23, 2002 @03:33PM (#3574598)
    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

    • Thanks for the clarification! I scoured the web for the real journal article but didn't find it. I did find an abstract for one of the 1993 papers you mentioned, so I wondered about the mass discrepancy. Better luck helping reporters get it straight in the future. Take their presence as a sign that your work is interesting to lay people.

      Since I'm a little rusty, I dug up some articles about type I and II supernovae [ohio-state.edu], and white dwarves and the Chandrasekhar limit [gsu.edu]. I also found a stellar who's who [mpa-garching.mpg.de] which says HR 8210 is IK Pegasi, at RA 21h26m Dec +19.3. My Sky Atlas 2000.0 shows a 6th-magnitude star there, but it's not marked.

    • Just let me know when to duck.
    • It is a shame that Karin is unhappy about the coverage she received. New Scientist always tries hard to make its stories accurate and I thought the article itself dealt with the criticisms she has now raised. For example, I do not say that Karin discovered the system but that the system was discovered in 1993 and that Karin stumbled over it while studying for a college paper. My understanding from talking to her, her supervisor Dave Latham and a third supernova researcher is that it is a very good supernovae candidate. We were not able to include further information about the evolution of this system because the third researcher wished to do more work before granting an interview. As to whether or not 0.3 solar masses is "just shy" of the Chandrasekhar limit, make up your own mind. This was certainly the reason the researchers themselves were excited by this system, and surely the job of a science reporter is to capture the excitement in an article. Karin's final point is that the star will probably be well away from the Earth when it explodes. This too is made clear in my article.
  • Here's some quick calculations that might put some things in perspective:

    1. Volume of the galaxy, assuming a disc 50,000 ly in radius and 2000 ly in thickness is about 8e12 cubic ly.
    2. Volume of space within 200 ly of Earth is about 3e7 cubic ly.
    3. Assuming the distribution of supernova events is fairly even throughout the galactic disc, that means one out of every 300,000 supernova events is within 200 ly of Earth.
    4. Based on an estimated frequency of once every 100 years, a supernova should occur within 200 ly of Earth on average once every 30 million years.

    Now, I'm ignoring the galactic halo, which has a low stellar density, and the fact that supernovae will tend to be more common towards the center of the galaxy, but that shouldn't change this estimation by more than an order of magnitude. If my calculations are correct, then this means that Earth must have been near supernovae several times in the past 4.5 billion years. Therefore, if all this is true, then life on Earth must be pretty resilient if we're here talking about it today.
    • Based on an estimated frequency of once every 100 years, a supernova should occur within 200 ly of Earth on average once every 30 million years.

      Which almost happens to coincide with the biggest extintions of life here on Earth. If I remember correctly, they've been happening every 33 million years or so.

      ...life on Earth must be pretty resilient if we're here talking about it today. Unlike those puny, non-resilient dinosaurs of our past. Sucks to be them, I say.

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