Supernova poised to go off near Earth

New Scientist ^ | Eugenie Samuel

[vannrox]

Supernova poised to go off near Earth

10:30 23 May 02

Eugenie Samuel

A student at Harvard University has stumbled across the terrifying spectacle of a star in our galactic backyard that is on the brink of exploding in a supernova. It is so close that if it were to blow up before moving away from us, it could wipe out life on Earth.

(Photo: SPL)

Most supernovae occur when large stars run out of fuel and then collapse under their own weight. As atoms in the star are squeezed together, they rebound outwards, blowing off energy in a dazzling and dangerous display lasting several weeks.

But this one is different. Called HR 8210, it is a humble white dwarf, a star that has run out of fuel and should be too small to produce a supernova. But it may not stay that way. First, it is not alone, but is orbiting a companion star in a typical binary system. And it is 1.15 times the mass of our Sun, which for a white dwarf is a whopper.

The system was first logged in 1993 but little attention was paid to it. Then when Harvard student Karin Sandstrom investigated HR 8210 for a college paper this year, she discovered that it is only just shy of the Chandrasekar limit - the mass at which it would be big enough to go supernova. That makes it the best and by far the closest supernova candidate discovered so far.

The crunch will come when HR 8210's companion begins to run out of fuel. As it expands to form a red giant star, its outer layers will be dumped onto HR 8210, pushing it over the Chandrasekar limit. "Our initial idea was that this might happen very soon," says Sandstrom's supervisor Dave Latham.

Too close for comfort

But do not panic yet. "Very soon" could mean hundreds of millions of years in the future. And that is just as well, because we are only 150 light years away from HR 8210 at present - well short of the 160 to 200 light years thought to be the minimum safe distance from a supernova. If it did let fly, the high-energy electromagnetic radiation and cosmic rays it released would destroy Earth's ozone layer within minutes, giving life little chance of survival.

This would not be the first time a supernova has changed the course of life on Earth. In 2001, Jesus Maiz-Apellaniz and colleagues from the Space Telescope Science Institute in Baltimore, Maryland, found a "smoking gun" supernova remnant, in the group of stars known as the Scorpius- Centaurus association.

The timing of the supernova corresponds to an otherwise mysterious deposit of heavy isotopes in deep Earth cores and to a mass marine extinction two million years ago. At the time, Scorpius-Centaurus was around twice as far away from Earth as HR 8210 is now.

Fortunately, it will take time for HR 8210 to accumulate the mass it needs. Preliminary calculations by Rosanne di Stefano at the Harvard-Smithsonian Center suggest this may take hundreds of millions of years. By that time it will be much further away, she says, though she still needs to confirm exactly how far. "I want to be sure I'm right."

But will similar stars threaten us before then? "The fact that there's such a system so close to us suggests maybe these objects are not so rare," says Latham.

10:30 23 May 02

[Poohbah]

1. I'm sure Osama bin Laden is behind this somehow.

2. How come Tom Ridge hasn't raised the alert condition to Orange?

[gitmo]

Does Bush know about this and when did he know it? We need an investigation. Someone hasn't been connecting the dots.

[lexington minuteman 1775]

Uh...what level of Sun protection do we need if a super nova goes off that close?Guess I better see if I have insurance coverage as well.

[michigander]

Fortunately, it will take time for HR 8210 to accumulate the mass it needs. Preliminary calculations by Rosanne di Stefano at the Harvard-Smithsonian Center suggest this may take hundreds of millions of years. By that time it will be much further away, she says, though she still needs to confirm exactly how far. "I want to be sure I'm right."

Whew! Thanks Rosanne!! Wouldn't want you to jump the gun here or anything.

[Poohbah]

Daschle was briefed, but he was too busy figuring out how to spin his wife's lobbying on behalf of Boeing.

[SnuffaBolshevik]

My lawyer needs to be kept apprised of these types of situations. Do supernovas generate asbestos? :).

[Fish out of Water]

*Index Bump

[callisto]

Below was posted on SlashDot and Rense.com. It appears to be written by Karin Sandstrom.

Update On 'Threatening' Supernova
New Scientist Story
From Karin Sandstrom
Re: The New Scientist Article
5-25-2
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

[TADSLOS]

Just show where the snooze button is with the Supernova alarm. Might as well get a few extra winks in...

[Thud]

This is the usual idiocy by science reporters, and the New Scientist in particular (New Scientist = Junk Scientist). Here's the real thing from Jerry Pournelle's Current mail (May 27) - http://www.jerrypournelle.com/mail/currentmail.html:

"First to set your minds at rest we may have more than a few million years:

Hello, Regarding the supernova article...

This was posted to Slashdot (yes, yes, I know, it's just Slashdot) in response to this story:

-------------------------

>> 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

-------------------------

Best regards,

Lee Plaisted Skeptical Maine-iac ---

"...religions are a democracy of beliefs while science is a dictatorship of facts." --Ludwig Krippahl

Which relieves our minds something wonderful and reassures us that the usual state of reporting is where it has been for a while."

[michigander]

According to the Kyoto Protocol, since the student was located at Harvard University, the United States will be held reponsible for any and all effects to global warming that the super nova may produce.

[Salgak]

The problem with being within a couple of hundred light years of a Supernova, is that you're in range of a VERY significant initial gamma radiation pulse. Sufficient to sterilize a planet. And following the initial pulse, high-speed gases, moving at significant fractions of the speed of light. Just the thing to rip the atmosphere off of a seared planet.

[The Raven]

>>But do not panic yet. "Very soon" could mean hundreds of millions of years in the future.

There's always a catch on these things.

[jimtorr]

Oh, please........This sounds more like a publicity stunt by an aspiring astonomy student, to me. Did I miss something, or was there no corraboration from anybody else in the article? Besides Sandstroms supervisor, I mean?

The Chandra

[El Gato]

But do not panic yet. "Very soon" could mean hundreds of millions of years in the future.

Yep, or it could have happened 149 years ago, but the light and radiation just hasn't gotten here yet.

Fortunately, it will take time for HR 8210 to accumulate the mass it needs. Preliminary calculations by Rosanne di Stefano at the Harvard-Smithsonian Center suggest this may take hundreds of millions of years

Doesn't sound to me like it should. When the companion goes red giant, the "dwarf" could grab up the necessary matter essentially instaneously, on the scale of such things, which might mean years, but surely not hundreds of million of years. Of course we don't know when the companion will go red giant, assuming that that didn't happen a 149 years ago of course. Well, it sound like it will be quite a show when it happens, something to look forward to, other than the possibily of getting thourghly fried that is. :)

[The Raven]

>>...the United States will be held reponsible for any and all effects to global warming that the super nova may produce.

I'm happy to say I've solved the global warming problem. Just throw a handful of Kudzu seeds over your shoulder and run like h*ll.

[montag813]

It is so close that if it were to blow up before moving away from us, it could wipe out life on Earth.

Let's hope so. Mankind has outlived its usefulness.

[jimtorr]

Oh, please........This sounds more like a publicity stunt by an aspiring astonomy student, to me. Did I miss something, or was there no corraboration from anybody else in the article? Sandstroms supervisor doesn't count, unless he's a lot more respected than Latham.

I believe that the Chandrasekar limit applies to a star before it collapses. It's the act of compression that generates the energy to cause a star to blow. Adding more mass to a white dwarf would do nothing to cause a nova, super or otherwise.

Who is the New Scientist? The article is written for a popular audience, not for the astronomy student's peers. Has anybody seen this info published in a peer review journal? "Science" comes to mind, or even Scientific American, at least S.A. is written for a better educated popular audience.

[oust the louse]

How uncharacteristic for a reporter to not give all the facts.Most reporters do their homework and get all information correctly before going to print(sarcasm).We'll have to give this fellow a pass for being so excited about something happening in about a gazzillion years.Total bonehead...he'll get a good job with L.A Times or maybe the N.Y Times soon.I hear this type of reporting is the training for the big job....