Most. Powerful. Supernova. Evah.

By Phil Plait | October 10, 2007 1:30 pm

OK, dumb title. But look at this:

On the left is a field of random galaxies (labeled a through d). On the right is the same field, showing a new blip of light.

Not much to look at, is it? It’s a supernova, an exploding star; it went off after the first image was taken. It doesn’t look like much, but that’s because it’s 4.7 billion freaking light years away.

When a star explodes, it’s a titanic event of mind-numbing violence. It can emit as much light in a few days as the Sun does over its entire lifetime. Octillions of tons of gas explode outward at thousands of miles per second, and the radiation emitted can fry planets from trillions of miles away.

And this was no ordinary supernova. It’s the most powerful ever detected, twice as powerful as the most luminous ever seen before. It was found by astronomer Robert Quimby at the McDonald Observatory using a monster 10-meter telescope. a relatively modest 18″ telescope, then followed up with a monster 10-meter.

In general, by taking a spectrum of the object you can find its distance. Supernovae tend to emit light at specific wavelengths (colors) just like a neon bulb does. Since the Universe is expanding, the lines redshift, getting longer wavelengths the farther away the object is. If you can identify a few lines (some from oxygen, some from hydrogen, etc.) you can get the distance of the object fairly accurately. Initially, Quimby only saw one line, and wasn’t sure which one it was, so the distance wasn’t well-determined. He knew that if it were [OIII] (a green line emitted by oxygen) the supernova was the way the heck far away. It wasn’t until followup observations identified a magnesium line with the same redshift that the distance was nailed: 4.7 billion light years.

When that’s taken into account, Supernova 2005ap (or just SN2005ap) is the most powerful ever, dwarfing the previous record holder (SN2006gy, also found by Quimby).

The star that blew up was a bruiser, probably several dozen times the mass of the Sun. When it ran out of fuel in its core, the core collapsed. This sent out countless neutrinos (subatomic particles) like a bomb, which blew up the outer layers of the star.

Bang! Supernova.

What’s interesting is that it was thought just a few years ago that a supernova couldn’t get this strong. But SN2006gy last year and now SN2005ap make it clear that they do happen. It means there are some things about supernovae we still don’t fully understand. The idea now is that the core of the impending supernova gets so hot that it creates antimatter, and this adds energy to the explosion. I know it sounds weird, but in fact we see this production of antimatter (in the form of anti-electrons called positrons) all the time. Conditions in the cores of some stars are ripe for this kind of production, so it’s a likely suspect behind these monster explosions.

Supernovae are incredibly complicated, and even though many go off each year that we can study, the details of the explosion mechanism remain elusive. We love it when ones in the extreme go off like this, because it tests the ideas at their limits, and sometimes that makes it easier to figure out what’s going on. And sometimes it makes it worse! But this instance of incredibly high temperatures, pressures, and energies will be eagerly inserted into new models of supernovae, and we’ll be one step closer to understanding them.

Bang! Science.

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (40)

  1. Ian

    I can see Jesus’ face in the supernova!

  2. Gnat

    So, in order to wrap my brain around the sizes here – if this had gone off in the Andromeda Galaxy, what would it have looked like here? When terms like “Octillions” and “4.7 Billion LY” get used, I have a hard time visualizing it.

  3. Just Al

    BA: “It doesn’t look like much, but that’s because it’s 4.7 billion freaking light years away.”

    Meh. That’s so yesterday. Got anything that’s happening now?

    Actually, I find it interesting that this occurred, in a non-relativistic timeline, about 150 million years before this planet was a planet (or 4.69994 billion years before, depending on whether you’re as dumb as a box of rocks or not). So as the planet coalesced out of the dust around our sun, then firmed up, then got bombarded by lots of stuff, then got water, and an atmosphere, then lots of critters crawled out of the slime and bought new iPods, those little photons have been on their way here. They may have even been on their way somewhere else and we got in the path. Can you imagine the stories they could tell?

    Actually, it probably wouldn’t be all that interesting, since they’re not very bright. [I’ll stop now]

    It does give a small inking of the unimaginable amount of energy, though. Those photons aren’t just traveling towards us; they’re going in every direction. Shift a few hundred miles to the side and you’ll still see the supernova, intersecting a completely different line of light. And anywhere else on a sphere that’s 9.4 billion light years across.

    And in one little tiny, eentsy spot, a handful of photons register on a charge-coupled device and tell us something new about our universe. And then we can make stupid jokes about it! Is that cool or what?

  4. Xenu

    That’s not a supernova, a mate of mine in that vicinity of space had a party. Jeez, leave it to humans to complicate things…

  5. alfaniner

    Yes, my first thought was — That actually occured about the time our planet was born, and we’re just seeing it now. Cooooool!

  6. Lurchgs

    I *knew* I shouldn’t have had those beans!

  7. I’ll have ago at Gnat’s question, though the *real* astronomers may want to check my math and conversion.

    If SN2005ap had gone off in the Andromeda galaxy I get an apparent visual magnitude of about 2. Which means it would look like a fairly bright star. Actually as bright as the current brightest star in the constellation (Alpheratz, visual magnitude=2.1). It would outshine the Andromeda galaxy itself by a factor of 100+ (visual magnitude=4.4).

    Remember magnitude is ‘funny’, lower numbers are brighter and it’s a logarithmic scale so 2 is ten times brighter than 3.

    If it were at a distance of 10 parsec (~33 ly) this supernova would be close to turning night into day being over a billion times brighter than the full moon.


    Distance to SN2005ap = 4.7bly = 1.442 bpc.
    Apparent magnitude (from = 18.5
    Absolute magnitude = 18.5 – 5 x log10( 1.422 x 10^9/ 10 ) ~ -22

    Distance to M31 = 2.5 mly = 766,518 pc
    Apparent magnitude = 5 x log10( 766518/10 ) – 22 ~ 2

  8. So in terms of radiation, how close do you think it could have been to us without wiping out human life here on Earth? A few hundred light years?

  9. “When a star explodes, it’s a titanic event of mind-numbing violence. It can emit as much light in a few days as the Sun does over its entire lifetime. Octillions of tons of gas explode outward at thousands of miles per second, and the radiation emitted can fry planets from trillions of miles away.”

    I love this stuff. The insane numbers way beyond anything our puny brains were intended to deal with. I feel like I have to grab people by the collar and shake them when explaining this. “OCTILLIONS! DO YOU UNDERSTAND ME?!?”

    No offense Phil, but ‘Bang! Science.’ would have been about an octillion times cooler as a title :).

  10. I know very little about the physics involved in an event like this, but I do have a question: is it possible that the distance calculation could be thrown off by the incredibly high level of energy associated with this kind of event? In other words, the distance calculations are based on the redshift; is it possible that the physics involved can distort things so much that things seem to be closer or farther away than they really are?

  11. tacitus

    Now we need one to go off in our neighborhood — just not too close (not that there is much chance of that since there aren’t any good candidates close enough to be cause for concern).

    By the law of averages, we’re long overdue, I’m told.

  12. DrFlimmer

    @ James Snell:
    The good thing is that most of the energy is converted into radiation. And radiation has the big advantage of travelling with only one precise speed – light speed. Red shift would only get into trouble if the speed of light changes over time, but there is (so far as I know) no evidence that it does. So it is quite a good way determining the distance between a shiny object and us.
    But the high amount of energy does have an effect: We can see it. With more energy and hence more radiation the object becomes brighter, so it is easier to detect for us. This is about the “apparent and absolute magnitude” NoAstronomer explained above.

  13. Ok, thank you. I’ll have to digest that for a minute or two but at first glance it makes sense ;-).

  14. Barbara

    Redshift may not be an indicator of distance.

    Low mass electrons, when jumping energy levels would emit or absorb correspondingly longer wavelengths….

  15. Why is it that the galaxies appear dimmer in the second picture? Are they underexposed on purpose so that the supernova wouldn’t appear overexposed (not sure how a source of light can be overexposed, but anyway)? If this is the case, whoa, an explosion that can outshine galaxies!

  16. That’s not a supernova, it’s a very small portion of the “missing mass” from that kilogram reference that I told you I have.

    I’m serious, I stole the mass, and sent a very small amount of it back in time, far, far away, and detonated it with my superhuman powers as a demonstration of my seriousness in all things… um… serious.

    A signed copy of your book will get me to stop. Otherwise, uh, well, I won’t.

  17. Grand Lunar

    So this supernova outdoes the one last year that is thought to have produced antimatter? Too cool!

    A rant:
    Let’s see astrologers, creationists, and other quacks try to match something like this for coolness.

    Only with science have we been able to spot this sample of the universe’s power. That’s right, science. Science! SCIENCE!

    End of rant

  18. Actually NoAstronomer, the magnitude scale is funnier than that. The difference between magnitudes is 2.512 times–not 10. (That’s because magnitude 1 is defined to be 100 times brighter than magnitude 6.)

  19. Simon Coude

    I did not even know such stars could exist! 100+ Solar Mass? I read there are even some with 250. The size of these gigantic stars is mind blowing by itself.

  20. Matt Haffner

    Minor quibble: This discovery was actually first found using an 18-inch (that’s 0.45 m) telescope that does the hard work of the searching. The follow-up (and better) images and spectroscopy are done using the 10-meter HET–and Keck, now that I’ve read the paper–telescopes. The big guns give us great results, but the little guys, used creatively, are still pounding out great discoveries too.

  21. BlondeReb3

    The happy thing is I understood most of that thanks to my undergraduate Astronomy course (where we used Dr. BA’s “Bad Astronomy” as one of our many texts).

    I hear rumors of Supernovas that have been so bright you can see them in the daylight. Now THAT I want to see?

    Predictions anyone? When will Betelgeuse join the ranks of the supernovas?

  22. BlondeReb, where did you take that class? I’ll have to thank your prof. :-)

    NoAstronomer, a normal SN would be about mag 4, and this one was very powerful. SN2006gy had an absolute mag of -22, so this one would have been about -23. Andromeda has a distance modulus of 24.4, so this SN would have been at mag 1.4 or so. Close enough, I guess! Bright enough to see easily, even if it were close to the nucleus.

  23. Matt, oops! You’re right; that got messed up when I was finalizing this post. :( I fixed it; thanks!

  24. tacitus

    I hear rumors of Supernovas that have been so bright you can see them in the daylight. Now THAT I want to see?

    The supernova that formed the Crab Nebula was visible in daylight for 23 days in 1054. Kepler’s Star, which exploded in 1604 was also seen during the daytime.

    I guess that any supernova on our side of the galaxy has a chance of being a daylight object for a short while, but it would depend on exactly where it was. We’re overdue — on average, a galaxy the size of the Milky Way is has one every 50 odd years or so. We haven’t seen one in 400 years.

    Question: now that we have detectors for all sorts of particles and waves, would we be able to detect a supernova if it happens at the other side of the Milky Way, out of sight of Earth?

  25. nate

    I’m confused. How do neutrinos blow off the gas? Are there really so many neutrinos or the gas so dense that a lot of gas gets pushed (i.e. the small reaction cross section of neutrinos reacting with nuclei is overwhelmed by the sheer number of interactions)? Or something else?

  26. TAMU Student


    The mass of the electron is a constant.

  27. Nigel Depledge

    “When it ran out of fuel in its core, the core collapsed. This sent out countless neutrinos (subatomic particles) like a bomb, which blew up the outer layers of the star. ”

    I don’t think this is right, BA.

    IIUC, neutrinos hardly interact with matter at all. I cannot envisage even octillions of them blowing off the outer layers of a star.

    Again IIUC, when the star’s core collapses (due to the cessation of nulcear fusion and hence the absence of radiation pressure to support the rest of the star), the intermediate layers of the star also collapse towards the core, but slower. Once the core stops its catastrophic collapse (due to a new set of fusion reactions starting, or due to electron degeneracy pressure, or neutron degeneracy pressure, or whatever), the collapsing intermediate layers smash into this, creating a shock wave that is then propagated throughout the rest of the star. It is this shock wave that blows off the outer layers of the star.

  28. Given that we seem to be finding “odd” supernovae recently, how does this affect their use as standard candles? Particularly, I am interested in their use as evidence for the accelerating expansion of the universe.

  29. Irishman

    I’m still confused as to how you can identify a spectrum line to a specific element. Isn’t the way you identify the element by the wavelength of the band? But redshift moves the wavelength? So how do you ensure you’re identifying oxygen III at a redshift of 4 and not, say, hydrogen at a redshift of 2.5? (Numbers made up and have no expectation of conforming to reality.) This has bothered me for a long time.

  30. Sergeant Zim

    Tacitus, whenever I see anybody mention the SN of 1054 I am reminded of this (Paraphrased from James Michner):

    “In 1054 a star exploded. it’s remnants are what we know today as the Crab Nebula, and the supernova was so bright it was visible in daylight over the entire Northern Hemisphere for over 3 weeks. Chinese astronomers duitifully recorded this unusual occurance, as did Arabic and Greek. European histories of the time, however, make no reference to this amazing sight, even though it was just as visible from Europe.
    In Europe, in 1054, the Dark ages were in full swing, with the Church in absolute control over the lives of everyone, from the king to the lowest serf.

    An age is not called “Dark” because the light does not shine, but because we refuse to see it”…

  31. Austin Armadillo

    There are a couple of ways that astronomers can make sure their redshift measurement is correct. First, look at the elements involved. A Type II supernova throws out lots of hydrogen. So, you’d expect the strongest lines in the spectrum to be from hydrogen. If you identify the strongest line as H-alpha and the second-strongest as H-beta, then calculate the redshift for each line and get the same number for both, that’s pretty good confirmation that you’ve identified the lines (and the redshift) correctly.
    Also, astronomers will use the pattern of lines. They might expect certain lines of hydrogen, oxygen, sulfur, etc to be present in the spectrum. So they look for that pattern of lines at longer wavelengths. If the pattern shows up as expected, but with a redshift of e.g. 1, then the presence of all the various lines shows the redshift calculation is correct.
    I wish I could come up with a good analogy, but the closest I could think of was installing wallpaper with stripes and making sure the stripes line up, which isn’t really the point I was trying to make. Maybe one of the cleverer readers can think of something!

  32. Might someone help by explaining to me the relationship between antimatter and the Weak Force? I understand they are related, but I do not know how. Thank you

  33. Roy Batty

    ‘it’s a titanic event of mind-numbing violence.’

    ‘Octillions of tons of gas explode outward at thousands of miles per second, and the radiation emitted can fry planets from trillions of miles away.’

    Ok, now I know the BA must have read too much E.E.Doc.Smith – but where are the ‘coruscating, ravening beams of unstoppable force?’ 😉

  34. Nigel Depledge

    Roy Batty said:
    “Ok, now I know the BA must have read too much E.E.Doc.Smith – but where are the ‘coruscating, ravening beams of unstoppable force?’”

    They must have met an immovable object . . .

  35. There is no such thing as too much Doc Smith.

  36. I’m curious about the reason why the analysis of SN2006gy was finished earlier than SN2005ap — was the further distance the main cause, perhaps? i.e. the magnesium line was much harder to find.

  37. Buzz Parsec

    Sean, there are several types of supernovae. The type 1a’s used as standard candles all look very similar to each other. Other types look quite different and are much more variable in intrinsic brightness. This one isn’t a type 1a, and is much brighter than a type 1a. See the Wikipedia article about Supernovas for a summary of the types and what causes type 1a’s and how that makes them useful as standard candles.

    The types differ from each other in the shape of their light curves (how they brighten and then dim as time passes), how long they stay at maximum brightness, what spectral lines are visible (which changes with time differently in the various types), etc. Almost all supernovae fall into a handful of types using this classification scheme, and only the type 1a’s are sufficiently similar to each other to be used as standard candles. Neither the distance nor red shift nor intrinsic magnitude are used as criteria for determining the type, so this is not a circular classification scheme (though once you determine this other information, you can tell a lot more about the particular supernova and about the galaxy it originated in.)


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