IRA FLATOW, host:
You're listening to Talk Of The Nation Science Friday. I'm Ira Flatow. As I said before the break, sometimes it's good to be in the right place at the right time. And that's what happened earlier this year to a team of astronomers watching a supernova. They got an unexpected treat. Their instruments happened to be pointed in just the right direction to witness the earliest stages of a second supernova occurring nearby, and they caught the event quickly enough to alert astronomers around the world to join in the observations. They observed and recorded something no one had ever seen before, the spectacular early stages of the supernova explosion.
Joining me now to talk about it is Alicia Soderberg. She is a Hubble Postdoctoral Fellow and a Carnegie-Princeton Fellow in the Department of Astrophysics at Princeton University in Princeton, New Jersey. And she was the one that caught the initial glimpse of the supernova through instruments on NASA Swift satellite, and you can see photos of that on our website at sciencefriday.com of that explosion. Welcome to Science Friday.
Dr. ALICIA SODERBERG (Postdoctoral Fellow, Astrophysics, Princeton University, New Jersey): Thank you.
FLATOW: That was sort of lucky, huh?
Dr. SODERBERG: It was extremely lucky, yes.
FLATOW: But you were prepared to see it.
Dr. SODERBERG: I was prepared. Yes. I have to say it's a great way to start off my career.
(Soundbite of laughter)
FLATOW: Well, let's back up a bit, and talk about what a supernova is.
Dr. SODERBERG: Sure, supernovae actually represent the explosive death of massive stars. We've actually observed them through the centuries. They're pretty extraordinary and spectacular. They actually put out as much light as a hundred million times the light of our own sun.
FLATOW: And how do they get there?
Dr. SODERBERG: So supernovae, as I said, are the result of the death of these very massive stars, and we know that they're actually quite rare. They only happen about once every hundred years per typical galaxy.
FLATOW: Hmm. And so, the star then has a finite lifetime, and it's - when it stars, the fires, the nuclear fires within the core start going out, the star collapses.
Dr. SODERBERG: Yes, it's very much like humans or animals. Basically, the stars grow older, and they try to adjust to that, but eventually at the end of the day they run out of fuel. And they have to succumb to their own gravity, and at that point, a shock wave is born, and the star erupts, explodes in spectacular fireworks.
FLATOW: And you were able to just be in the right place at the right time to see the beginning of these fireworks.
Dr. SODERBERG: Yes. The probability is very small. But I actually was the one that got to see it first hand.
FLATOW: Did you know what you were seeing at the time?
Dr. SODERBERG: No. That's what actually made it so exciting. That I didn't know what I was seeing, the first time. And of course, again, I was studying another supernova. So, I'm very trained in supernovae, but I thought this might actually be something else, something more exotic. So, it was pretty exciting to just react to thinking that this is something unknown.
FLATOW: What do you - can you describe to us what you actually see? What does it look like? A smudge, a dot or - when you first saw it, and say, oh, there's something interesting happening here?
Dr. SODERBERG: So again I want to applaud the Swift satellite because it's really extraordinary, and they actually beamed down to earth the images that they take, both in x-rays and gamma rays, and also invisible light. They do this several times a day. So actually I just got to look at images, the same kind of images that you would look at with your digital camera. And I saw this extraordinarily bright source. It was sort of like pointing your digital camera at the sun. It just swamped the whole image.
FLATOW: And that was in the x-ray, right?
Dr. SODERBERG. That was in the x-rays, yes.
FLATOW: Wow. And so you got excited and started emailing people.
Dr. SODERBERG: Exactly. Yes.
FLATOW: Text messaging them, something.
Dr. SODERBERG: I've been in this field long enough to know, you just have to react quickly, and know that the next few months of you life are probably going to be forever much changed.
FLATOW: And you say the next few months. Why the next few months?
Dr. SODERBERG: Of course it takes a long time to, sort of, put together all the pieces of this puzzle, and try to understand exactly what happened that day, January 9th, when this star decided to explode. And so it's really great to put together the best collaboration of people, to put the pieces of that puzzle together, and figure out all of those details out.
FLATOW: So you needed other astronomers to confirm what you were doing, to back you up, to help collect the data? To what?
Dr. SODERBERG: Certainly, a lot of clues came from using other telescopes. So the first thing I had to do is call many of my friends, and again, some of the best people in this field, and get them to turn the biggest telescopes in the whole world on this point in the sky at that very time, to try to understand better at other wavelengths besides x-rays what actually had happened.
FLATOW: So you had all this different telescopes that are looking at different colors in the universe there.
Dr. SODERBERG: Exactly.
FLATOW: And they all were just as awestruck as you were.
Dr. SODERBERG: Yes. Yes.
FLATOW: How - what are the odds of actually seeing this, something like this, do you think?
Dr. SODERBERG: Incredibly, incredibly small. In fact, the chance that a particular galaxy such as this very ordinary galaxy of having two supernovae within just a few weeks of each other, is about one in 10,000. And then the chance that I would actually be observing that galaxy at the time that other star exploded is just unfathomable.
FLATOW: Now what do you learn from being able to see it so early?
Dr. SODERBERG: So, a careful study of these x-rays, this pulse of light that signaled the death of the star actually encodes a lot of the physics about how massive stars die. And in this particular case we can show that this star was actually not so big. It was about the size of our own sun but it was very, very massive. So this was a very massive star that lived a great life but died very young.
FLATOW: And so a teaspoon full of the star would weigh how much?
Dr. SODERBERG: So the star was actually not that much heavier than this - than our particular sun. What actually makes this star so exciting is that it, sort of, went on a big diet before it exploded. It lost a lot of weight, and that's how it came to its eventual demise, that it was just really trying to keep up with the fact that it was really heavy. And it knew it was going to die soon if it didn't get rid of this weigh.
FLATOW: And where is this star?
Dr. SODERBERG: So this is in a pretty typical galaxy. It's located in the constellation links. And it's a hundred million light years away.
FLATOW: Pretty close then.
Dr. SODERBERG: Yes. Yes, it is close. It sounds far away, but it's actually not that far.
FLATOW: Can we see this with our backyard telescope?
Dr. SODERBERG: So, with a backyard telescope you might have actually been able to pick up on some of the very early visual light that we say from the supernova itself. What's so exciting is that in the x-rays which is invisible to the human eye, unfortunately, the supernova was a thousand times brighter.
FLATOW: Wow. So we don't have our own x-ray telescopes.
Dr. SODERBERG: No, unfortunately.
FLATOW: To see that. So, well, you were actually looking back in time then, right?
Dr. SODERBERG: Exactly.
FLATOW: A hundred million years ago.
Dr. SODERBERG: Yes.
FLATOW: And how many more do you think there are out there like this one waiting to be discovered?
Dr. SODERBERG: So that's what the most fantastic part of this discovery is, is that we've shown that this particular supernova was very ordinary. It looked just like all the other supernovae that we had seen, only after we had seen the visual light, which takes about a month to actually get very bright and glow strongly. So since this is such an ordinary star and ordinary explosion, we think that all supernovae produce such a bright x-ray pulse. And that's pretty exciting that they all do this spectacular fireworks.
FLATOW: And what happens to this stuff that gets thrown out of the fireworks itself? What happens to all that material?
Dr. SODERBERG: That's also very exciting. So all of that material of course goes out to enrich or sort of fertilize the universe. And it's through this fertilization that new stars are formed, and in turn new planets, and hopefully new life on those planets.
FLATOW: Let's go to the phone. Sam Dippen(ph), Detroit. Hi, welcome to Science Friday.
SAM (Caller): Yes. Thanks for having me. My question is, you said that scientists were lucky to be watching that portion of the sky when this event happened. Now my question is, if your guess can estimate how much portion of the sky is continuously being watched by some telescope or the other at any given moment? One percent, two percent, five percent? And I'll take the answer off the air. Thanks so much.
FLATOW: You're welcome. Good question.
Dr. SODERBERG: Yes, so right now, with our current x-ray telescopes, which of course are doing a fantastic job, but unfortunately they don't see much of the universe at any one time. We only see a very small postage stamp, a very small percent. So that's what really makes this discovery so extraordinary, and we look forward to future x-ray satellites being built now that see the whole sky at any one moment all the time. All the sky, all the time.
FLATOW: Why are x-rays so important?
Dr. SODERBERG: So as we now know, this is the best way to actually discover supernovae. The x-ray light actually marks the time of explosion. It's very short-lived, it only lasts a few seconds to minutes, but it actually marks the explosion of the star, and this is the best way to actually get the best data, because you know exactly when the star started, the explosion started, rather than having to wait for the visual light to build up in strength over the next month.
FLATOW: So the - it will get brighter visually, you know.
Dr. SODERBERG: Visually, yes.
FLATOW: It will.
Dr. SODERBERG: It takes about a month though which is - usually the time that most supernovae are found today is a month after the explosion when all the fireworks have already ended.
FLATOW: All right. And will we be able to see it ourselves then or it's never going to get big enough for our - my little binoculars?
Dr. SODERBERG: No. You know what? What's really phenomenal, what I love about the field supernova studies is still a very significant portion of all supernovae are actually found by amateur astronomers. They're very dedicated to this field, and they provide scientists with very important clues.
FLATOW: So we might be able to see it after all, on a good night. Where should we look again?
Dr. SODERBERG: Ah, so this is on the Princeton website.
Dr. SODERBERG: The media press kit, that you can see actually the star in the act of exploding.
FLATOW: Can we - where in the sky should we watch for this?
Dr. SODERBERG: So this particular object is in the constellation Links, so it's in the northern hemisphere. It's only accessible through northern telescopes, unfortunately. But as I said, we now know that through these early warning beacons we should see more of these all the time.
FLATOW: Or are - would you expect more astronomers are going to want to become famous overnight like you have, and start looking for more of these?
Dr. SODERBERG: Of course. I mean, it's actually become a very important discovery not just, you know, for the general public but the astronomical community has really reacted. This is a very important discovery that's really going to change forever the way that we discover and study exploding stars.
FLATOW: Well, congratulations to you and...
Dr. SODERBERG: Thank you very much.
FLATOW: Good luck to you and thank you for taking time to be with us.
Dr. SODERBERG: Great. Thank you.
FLATOW: Alicia Soderberg is a Hubble Postdoctoral Fellow and a Carnegie-Princeton Fellow in the Department of Astrophysics of Princeton. And she's the one that caught the initial glimpse of the supernova through instruments on NASA's Swift Satellite.