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Visible Supernova in M82
January 22, 2014 10:08 AM   Subscribe

There's a new light in the night sky. Around 12 million years ago, a star exploded in the galaxy M82. The light reached earth today.

Even better, astronomers suspect this may have been a Type Ia supernova, a so-called "standard candle" by which vast cosmic distances may be measured along with the age of the universe itself.

M82 is visible near the Big Dipper, and the supernova itself should be observable tonight with binoculars.
posted by R. Schlock (80 comments total) 35 users marked this as a favorite

 
Bad Astronomy link.
posted by Pendragon at 10:14 AM on January 22 [3 favorites]


I think we saw this and will look for it tonight if this storm clears. Thanks!
posted by vrakatar at 10:15 AM on January 22


. x billions x billions
posted by save alive nothing that breatheth at 10:19 AM on January 22 [3 favorites]


I'll believe it when I see it for myself.
posted by mazola at 10:20 AM on January 22 [1 favorite]


Around 12 million years ago, a star exploded in the galaxy M82. The light reached earth today.

"I knew I shouldn't have taken that left turn at Albuquerque!"
posted by Atom Eyes at 10:22 AM on January 22 [1 favorite]


Oh, and this is really cool!
posted by Atom Eyes at 10:24 AM on January 22 [1 favorite]


But Alderaan is a peaceful planet!
posted by Curious Artificer at 10:25 AM on January 22 [17 favorites]


...in all seriousness, I do always wonder if any life got exterminated. I realize it's pointless, and probably childish, but I still wonder.
posted by aramaic at 10:28 AM on January 22 [5 favorites]


Good thing it's so far away!
posted by Blazecock Pileon at 10:29 AM on January 22


Just looking at my week-long cloudy forecast - how long can we expect this puppy to keep glowing? I see nothing in the links.
posted by Brodiggitty at 10:31 AM on January 22


The odds of something arriving on one day out of 12 million years seems insane.. but I guess it makes more sense when you think of the sheer number of stars out there.
posted by starman at 10:40 AM on January 22 [2 favorites]


Just looking at my week-long cloudy forecast - how long can we expect this puppy to keep glowing? I see nothing in the links.

Bad Astronomy link states that it looks like it was discovered two weeks before peak brightness.
posted by rocketpup at 10:43 AM on January 22 [1 favorite]


THE SIGN IS GIVEN.

PROCEED TO YOUR DESIGNATED LOCATIONS FOR PHASE 2.
posted by blue_beetle at 10:44 AM on January 22 [20 favorites]


...in all seriousness, I do always wonder if any life got exterminated. I realize it's pointless, and probably childish, but I still wonder.

That got me wondering too, so I poked around at wikipedia a bit. Apparently folks think a supernova within a couple thousand light years of earth could potentially affect us. So maybe a million+ systems could have been affected by this.

Of course, nobody knows how common life is, or when there is life, how often it evolves into something cute and fuzzy that just wants to cuddle.
posted by aubilenon at 11:00 AM on January 22 [2 favorites]


I do always wonder if any life got exterminated. I realize it's pointless, and probably childish, but I still wonder.

Many planets, including two gangster planets and a cowboy world.
posted by mrgoat at 11:03 AM on January 22 [8 favorites]


PROCEED TO YOUR DESIGNATED LOCATIONS FOR PHASE 2.

REQUEST RE-TRANSMISSION OF PHASE 2 RALLY POINT INSTRUCTIONS. ARRIVED AT ABANDONED TOLEDO BURGER CHEF WITH 40 VACUUM CLEANERS, 163 GLAZED DONUTS, A BOX OF 12 3-PRONG POWER OUTLET ADAPTERS, AND THE REANIMATED HEAD OF SOUPY SALES. NO SIGN OF OUR ASSIGNED CONTACT AGENT "THAT GUY STEVE FROM UTAH" OR THE CACHE OF BOILED PEANUTS. PLEASE ADVISE. SUSPECT POSSIBLE ERROR IN DECODE OF ORIGINAL ORDERS.
posted by chambers at 11:03 AM on January 22 [10 favorites]


M82, huh. On an unrelated note, is the band M83 named after the galaxy?
posted by resurrexit at 11:07 AM on January 22


I do always wonder if any life got exterminated.

In a perverse way, you should hope some life was exterminated, because if it wasn't, then life is very rare indeed and we may never find any out there.
posted by dhartung at 11:07 AM on January 22 [5 favorites]


Chambers, did you forget to run it through the transplanar fourier transform then ROT-13 it? I had the same thing happen, and doing the above fixed it for me.
posted by symbioid at 11:09 AM on January 22


Wow, what I doing 12 million years ago. Come on brain, think...
posted by From Bklyn at 11:10 AM on January 22 [1 favorite]


On an unrelated note, is the band M83 named after the galaxy?

According to Wikipedia, it is.
posted by Blazecock Pileon at 11:12 AM on January 22


I thought I felt a disturbance in the Force, last night...
posted by littlejohnnyjewel at 11:15 AM on January 22 [1 favorite]


Amazing!
posted by LobsterMitten at 11:22 AM on January 22


Could someone please make a better animated gif with the before and after shots equalized? The one in the first link makes it look like about 7 different stars all went supernova at the same time.
posted by straight at 11:28 AM on January 22 [2 favorites]


The light took 12 million years to get here? How many light years away was the star?
posted by dances_with_sneetches at 11:28 AM on January 22 [1 favorite]


That's a joke, right?
But it's more interesting to contemplate that distance as light zooming at 300,000 kilometers per second traveling for 12 million years.
It's also fascinating to contemplate that what we see when we look at the stars is not accurate. Over those vast distances, stars have moved, died out, and others have been born, and we're looking at them, but we can't see them yet.
posted by weapons-grade pandemonium at 11:38 AM on January 22 [1 favorite]


exploding cigar...Douglas Adams is probably right about a lot.
posted by j_curiouser at 11:47 AM on January 22


Well - I think one of the questions that's interesting is... not where it was (I mean, we're seeing it where it WAS) but where is it now? Not only that. The time it takes light to reach us is not the same as the actual distance an object is away, due to the fact that space-time itself is continually expanding, which means that if the light took 12 million light years to get here, the star is more than 12 million light years away. Conversely, if the star is 12 million light years away, it actually took less than 12 million light years to get here. Wait - is my logic right on that?

Physics is really damn freaky and I get confused :\
posted by symbioid at 11:52 AM on January 22


The light took 12 million years to get here? How many light years away was the star?

But it's more interesting to contemplate that distance as light zooming at 300,000 kilometers per second traveling for 12 million years.

Even more interesting to consider where the remains of the star and surrounding system are now, and what the current distance we are from that. We are seeing the position of the supernova from 12 million years ago. Whatever solid matter in the area that survived the supernova has been moving for 12 million years, and is a long way from where we see it now, and unless something massively changes in how we understand physics, we'll never be able to observe from here what's happening with it "right now" ('now' being used in the everyday kind of way here). We'll always have that 12 million year gap.
posted by chambers at 11:53 AM on January 22 [1 favorite]


I do always wonder if any life got exterminated.

I think it's less likely for a Type 1a, since that's a binary star (white dwarf plus another more-or-less ordinary star), and while that doesn't exclude planetary systems, (and the planets might orbit the dual-star or orbit only one of the stars), it seems like the continual pull of material from the one sun into the white dwarf would make for some really unpleasant conditions with respect to solar radiation.
posted by CheeseDigestsAll at 12:02 PM on January 22


Be on the lookout for any virgin births today!
posted by charred husk at 12:03 PM on January 22


For a bit of supernova related physics wankery, I thought this what if was really good.
posted by Ned G at 12:07 PM on January 22 [1 favorite]


If the clouds break as predicted here I will be grabbing a shot. I need to sleep now especially if I will be up late, but briefly:
This is a 1a. 1a's are cosmologically awesome as already stated.

Supernovae last typically for weeks, and we are before the peak. You have a couple of weeks at least to try to see this with binoculars and if you can find a telescope even better - although it may not look much different than a star.

Anyway, 1a (more typically Ia, but 1a gets across the type-1ness more) really are amazingly important and famously 2011-Nobel-worthy.
posted by edd at 12:25 PM on January 22 [1 favorite]


It's also fascinating to contemplate that what we see when we look at the stars is not accurate. Over those vast distances, stars have moved, died out, and others have been born, and we're looking at them, but we can't see them yet.

In Sandman, Neil Gaiman had a character say, "I like the stars. It's the illusion of permanence, I think. I mean, they are always flaring up and caving in and going out. But from here I can pretend... I can pretend that things last. I can pretend that lives last longer than moments. Gods come, and gods go. Mortals flicker and flash and fade. Worlds don't last; and stars and galaxies are fleeting, transient things that twinkle like fireflies and vanish into cold and dust. But I can pretend... "
posted by ricochet biscuit at 12:27 PM on January 22 [3 favorites]


Conversely, if the star is 12 million light years away, it actually took less than 12 million light years to get here.

Yeah, well, the difference in positions is like 10,000 ly. The "12 million lightyear" figure is +/- 800K. So, everything is moving, but not enough that it's a big part of this story.
posted by aubilenon at 12:31 PM on January 22 [2 favorites]


chambers: "Even more interesting to consider where the remains of the star and surrounding system are now"

That would require a cohesive defition of now, which doesn't really exist. Universal simultaneity is impossible in special relativity.

On these kind of scales, time... doesn't really work the way we think it does. "Now" is meaningless when 'past', 'present', or 'future' depends on where you are and how fast you're going.
posted by danny the boy at 12:37 PM on January 22 [10 favorites]


...in all seriousness, I do always wonder if any life got exterminated. I realize it's pointless, and probably childish, but I still wonder.

Probably not. There are core collapse supernovas and these, which are white dwarf overload-and-explode. The first only happens to very large stars, which have very short lifespans, so life evolving around them is unlikely. The amount of energy they emit doesn't help either.

The second happens to a white dwarf in a binary system, where the first star has already gone through the red giant phase and become a white dwarf, and the second is entering into the giant phase. While these stars can have multiple billion year long lifetimes -- indeed, a white dwarf is the fate of the Sun -- any life in the neighborhood was probably already driven to extinction in the red giant phase.

It's possible a star faring society could have colonized, but if you have the tech to colonize, you have the tech to detect an incipient Type Ia supernova, and would be smart enough to stay away from stars likely to undergo core collapse supernova.
posted by eriko at 12:39 PM on January 22 [1 favorite]


Yeah, from a working standpoint this galaxy is so so so close that the light travel time/cosmological effects aren't really too much of a concern, although all the dust and gas that the light runs into on the way to is much more of one.
posted by McSwaggers at 12:43 PM on January 22 [1 favorite]


Very sad. Somewhere, a symphony is debuting.
posted by runincircles at 12:59 PM on January 22 [1 favorite]


In the heart of a supernova.
posted by symbioid at 1:07 PM on January 22


Exterminated life wouldn't have to have been orbiting the star that went nova; supernovas are pretty lethal to life in star systems in the local neighborhood.
posted by Mitheral at 1:17 PM on January 22 [1 favorite]


I think it's less likely for a Type 1a, since that's a binary star (white dwarf plus another more-or-less ordinary star), and while that doesn't exclude planetary systems, (and the planets might orbit the dual-star or orbit only one of the stars), it seems like the continual pull of material from the one sun into the white dwarf would make for some really unpleasant conditions with respect to solar radiation.

You don't have to be in the same solar system to get wiped out by a supernova.

Near-Earth supernova

It's not the same type of nova, but a hypernova in a different spiral arm of our galaxy may have wiped half the ozone layer and caused the Ordovician extinction event. Kind of a sobering thought.
posted by Foosnark at 1:17 PM on January 22 [1 favorite]


...and that's what I get for taking too long to write my post.
posted by Foosnark at 1:17 PM on January 22


Also, while its perhaps not probable that every supernovae kills an alien kitten somewhere it is possible that some do. We would really need to understand the habitable planet/how long kife lasts probability much better than we do to say for sure because in some ways thats much more uncertain than the possibility of a supernovae having *potentially* life-altering effects on a planet (specifically, what stars and for what timeframes, and whats the duty cycle of life on a planet).

The danger comes essentially with the blast radius of the supernovae to the stars around it, not the system itself - IE how far away the ejecta will impact and the radiation will ionize, which could conceivably hurt other systems around them. Low mass core-collapse events and Ia's are around lower mass possible life supporting systems because stars move relative to each other, and into and out of spiral arms (where most but not all star formation happens, and many large supernovae), and some high mass stars get shot at high velocities in multi-star interactions, etc, etc.

For humans nothing nearby is a a real concern, but the nearest SN is actually a Ia candidate at ~150 light years, and theres another ~6ish Type II SN in the local area within ~1k light years, but nothing will probably explode in the 'near' (lets be generous and say a million or two years minimum probably) future, and those supernovae nearby aren't especially dangerous at their current distance. But, The earth is 4.5 billion years old, and assuming that the earth remains habitable-ish for a another few billion (its already been three!) the nearby stellar environment can change a lot during that time (thats like 15-ish Milky way traversal!). It's all a numbers game basically, with betting-odds that we're still trying to understand.
posted by McSwaggers at 1:18 PM on January 22 [1 favorite]


So the Bad Astronomy link already mentions this, but it's worth emphasizing: this is a tiny bit fishy.

M83 is a star-forming galaxy, where there are new stars being born. Some of these should be massive, burning hard and hot, and dying in supernova explosions (live fast, die young). This is not one of those ("core collapse" or Type II) supernovae.

Now, after one of those young stars has burnt out, what's left behind is frequently a compact object like a white dwarf. These can last for a long time - billions of years - and some of them can undergo a very different kind of supernova driven by accretion of matter on to their surface until gravity overcomes the quantum mechanical forces supporting the white dwarf. (How amazing is that? A titanic struggle between gravity and quantum mechanics, and sometimes, gravity wins with a bang...) And that's what this looks like: tentatively a Type Ia supernova caught 14 days before peak brightness.

So what's fishy is this: a Type Ia could happen in any old galaxy, but a Type II is much more likely to happen in a galaxy with recent star formation. Here's a supernova - a rare event - in a galaxy with recent star formation. How come it isn't a Type II?

Of course, it could be that the observers are wrong in their classification - if so, there will be a correction in the next few days. Or it could be statistical trickery: a Type II is more likely to happen in a star forming galaxy, but is a star forming galaxy may not be more likely to produce a Type II? Or maybe it's just luck: it's not that unlikely, I guess? But ... huh.
posted by RedOrGreen at 1:23 PM on January 22 [2 favorites]


Hey Foosnark, can I join your too-late-to-the-party club? I'll bring beer, and the images of PSN J09554214+6940260 (our temporary, but sadly less than poetic name for this supernova) that I've been helping with.
posted by McSwaggers at 1:25 PM on January 22


RedOrGreen: So what's fishy is this: a Type Ia could happen in any old galaxy, but a Type II is much more likely to happen in a galaxy with recent star formation. Here's a supernova - a rare event - in a galaxy with recent star formation. How come it isn't a Type II?

So, it's actually not all that fishy. M82 is really old, so it's had a lot of time to create stars, and which it is still doing. Now, those high mass ones explode very quickly and so we see lot's of them. Some of which do look kinda like Type Ia supernovae (these are type Ib/c supernova, where massive stars have lost most of their outer hydrogen/helium 'layer').

BUT, since this galaxy is very old it has been creating stars long enough that the lower mass and longer living binary systems that make Type Ia supernovae can start exploding also. And, it's so nearby that we can take much, much more precise measurements of it than other supernovae which is really helpful.

So it's a numbers game, and this is far from the only nearby spiral galaxy that we've seen these supernovae from, SN 2011fe is another good example. But, Type Ia are still pretty common from a supernovae rate perspective so it isn't a huge shock.

Now, what is much MORE hinkey are type Ia in supernovae in very young galaxies, or Core-Collapse supernovae in galaxies with very little star formation.
posted by McSwaggers at 1:35 PM on January 22 [2 favorites]


(For a supernova explosion any day now, take a look at Eta Carina. Maybe someone did a post once with some of these links?)
posted by RedOrGreen at 1:35 PM on January 22


I think it's less likely for a Type 1a, since that's a binary star (white dwarf plus another more-or-less ordinary star), and while that doesn't exclude planetary systems, (and the planets might orbit the dual-star or orbit only one of the stars), it seems like the continual pull of material from the one sun into the white dwarf would make for some really unpleasant conditions with respect to solar radiation.

I think the question regarding exterminating life was in reference to the effects on planets orbiting stars more suited to the development of life (as we know it) that are within a few light-years of the supernova.

By some estimates, the gamma rays from a type Ia supernova 100 light-years from Earth could strip most of the ozone layer away in addition to creating a whole ton of NO2.

Given how common exoplanets now appear to be, I don't think it's that much of a stretch to speculate about how much life could be wiped out. The speculation will really take off if we start finding O2 or other reactive components of exoplanet atmospheres.
posted by [expletive deleted] at 1:35 PM on January 22 [1 favorite]


I think the question regarding exterminating life was in reference to the effects on planets orbiting stars more suited to the development of life (as we know it) that are within a few light-years of the supernova.

But remember that supernovae are also the birth of life, since all the heavier elements fused from hydrogen in the original star are blasted into space, and eventually become planets, diamonds, dinosaurs, camelias, capybaras, people, and god knows what else. Every element in your body was born in a supernova.
posted by weapons-grade pandemonium at 2:03 PM on January 22 [1 favorite]


The odds of something arriving on one day out of 12 million years seems insane.. but I guess it makes more sense when you think of the sheer number of stars out there.

This is one of those awesome things that actually results in a deeper understanding of the real world by just thinking about it, like the thing where you know the universe is limited in either space or time because otherwise the entire night sky would be filled with starlight in every point.
posted by odinsdream at 2:08 PM on January 22 [2 favorites]


Unto us a sun is given:
and his name shall be called
PSN J09554214+6940260,
a Type Ia supernova,
a superdense white dwarf that has pulled hydrogen from a nearby companion until it collapses upon itself due to mass.

Hallelujah!
Hallelujah!
Halleh-eh-eh-eh-eh-eh-lu-jaaaaah!
posted by IAmBroom at 2:25 PM on January 22 [1 favorite]


12 million years, huh? When the three of our ancestors strolled across some damp sands at Laetoli, the light was 70% of the way here. When Alexander died at Babylon, it was 99.98% of the way here. The only thing I can compare it to is a Windows progress bar.
posted by ricochet biscuit at 2:29 PM on January 22 [11 favorites]


Wouldn't a star that is in the process of going supernova have probably already killed off any life on nearby planets many, many years prior to going supernova? When our star finally dies out it'll have been millions of years after it totally wrecked our planet and we'd either be dead long before it or we'd have fled the planet.
posted by gucci mane at 2:38 PM on January 22


My favorite image of this supernova so far is this series going back 7 days where, in retrospect, the Japanese astronomer Itagaki realized he'd captured images showing the thing brightening since January 15. It's mentioned in the last article linked in this post; I found it myself over in a Cloudy Nights discussion along with several other amateur astronomers saying "hey, I bet I accidentally took a picture of that!". Astronomy is one of the few sciences remaining where an amateur with relatively accessible equipment can still make important contributions to the field.
posted by Nelson at 3:18 PM on January 22 [1 favorite]


OK, so are the stars right now? How about now?
posted by Joe in Australia at 3:29 PM on January 22


OK, so are the stars right now? How about now?

Couldn't tell you. I'm not even writing this now.
posted by chambers at 3:31 PM on January 22 [1 favorite]


The odds of something arriving on one day out of 12 million years seems insane.

The odds are certain. The probability is 1. How about if you were to move the star closer, so it only took eight minutes? Would that be more sane?
posted by weapons-grade pandemonium at 3:50 PM on January 22 [1 favorite]


Crap. Clear skies here, but it's because the wind chill is below 0. Hopefully it'll last until going out with my telescope isn't so horribly cold. I'll do some observing in honor of John Dobson, who died a few days ago.
posted by jiawen at 3:50 PM on January 22


This is pretty exciting. It's a little too cloudy and light polluted here to see anything tonight, but fingers crossed I'll be able to train my shaky little telescope on it another evening.

It's amazing to me that something so huge could happen over a human scale like weeks.
posted by lucidium at 5:53 PM on January 22 [1 favorite]


The odds of something arriving on one day out of 12 million years seems insane.
As others have said, it's not that surprising. Plus a supernova like this last weeks, not a day. There's a reasonable number of galaxies closer than M82 - it's in the next group along from the local group if I recall correctly - and a supernova happens in a decent sized galaxy about once every hundred years, so you'll see things this close on vaguely decadal timescales.

And you've probably not experienced as I have the frustration of trying to pick up photons that have travelled for 8 billion years and have been stopped in the last thirty feet by cloud on the day you're at the other end of the telescope. That's when the odds aren't terribly unusual but the result definitely drives you insane.
posted by edd at 6:52 PM on January 22 [3 favorites]


Our First Glimpse of the Web that Connects All Galaxies
posted by homunculus at 7:17 PM on January 22 [1 favorite]


"It's amazing to me that something so huge could happen over a human scale like weeks."

That is amazing. Stellar evolution occurs over millions or billions of years, but the end stages that result in a supernova happen very quickly.

For example, consider a different kind of supernova, the Type II supernova, a product of a star between 8 and 50 times more massive than the Sun and which was still burning hydrogen.

This star, over its lifetime, will progressively burn up in fusion all its hydrogen and then heavier elements, until it reaches nickel and iron, both of which cannot be ordinarily fused. Each element it burns corresponds to a stage in the star's lifetime.

So, for example, let's look at a 25 solar mass star, which will have a lifetime of about 7.7 million years.

It will take it about 7 million years to burn up its hydrogen. When there's not enough hydrogen being fused to generate enough energy to balance the pressure of gravitational contraction, the star begins to shrink, raising the temperature by 5x, the density by 14x, and causing the helium (most of which was produced by the hydrogen fusion) to begin fusing into carbon, balancing against the gravitational pressure and returning the star to equilibrium.

It will take it about 700,000 years to burn up its helium. Again, when there's not enough helium being fused to generate enough energy to balance the pressure of gravitational contraction, the star begins to shrink, tripling the temperature, the density by 285x, and causing the carbon (which was produced by the helium fusion) to begin fusing into neon, balancing against the gravitational pressure and returning the star to equilibrium.

It will take it about 600 years to burn up its carbon. Again, when there's not enough carbon being fused to generate enough energy to balance the pressure of gravitational contraction, the star begins to shrink, doubling the temperature, the density by 20x, and causing the neon (which was produced by the carbon fusion) to begin fusing into oxygen, balancing against the gravitational pressure and returning the star to equilibrium.

It will take it just 1 year to burn up its neon. Again, when there's not enough neon being fused to generate enough energy to balance the pressure of gravitational contraction, the star begins to shrink, slightly increasing the temperature (by about 25%), the density by 5x, and causing the oxygen (which was produced by the neon fusion) to begin fusing into silicon, balancing against the gravitational pressure and returning the star to equilibrium.

It will take it just 6 months to burn up its oxygen. Again, when there's not enough oxygen being fused to generate energy to balance the pressure of gravitational contraction, the star begins to shrink, almost doubling the temperature, tripling the density, and causing the silicon (which was produced by the oxygen fusion) to begin fusing, in its own complicated sequence involving the alpha process, with the end result of nickel-56 (which radioactively decays into cobalt-56 and iron-56). This, as before, balances against the gravitational pressure and returns the star to equilibrium.

And now it will take merely 1 day to burn up its silicon. Finally, when there's not enough silicon being fused to generate energy to balance the pressure of gravitational contraction, the star begins to shrink.

This time, however, the core of the star is mostly nickel and iron, and they cannot ordinarily be fused into heavier elements, so as the star shrinks and the temperature and density increase, there is no nuclear fusion ignition of the nickel and iron to counteract the contraction. Here the limit of pressure and density is the electron degeneracy pressure, which is the resistance of electrons being forced to occupy the same energy states, which they can't.

But at solar masses this great, the gravitational binding energy is much greater than this, the contraction pushes past the electron degeneracy pressure, and then things happen very, very quickly — within milliseconds — and very, very violently. The outer core collapses inward at a substantial fraction of the speed of light and the incredibly increasing temperature creates extremely energetic gamma rays (light at extremely high frequencies) which hit the iron nuclei and energizing them so much that they spontaneously decay into alpha particles (a pair of bound protons, which is a bare helium nucleus) and neutrons. This is basically undoing the whole fusion process that led up to this.

But also, where there are still some of the lighter elements in the outer core, some of these can absorb these high energy alpha particles and neutrons, creating some of the elements which are heavier than iron.

All elements heavier than iron are necessarily the product of a supernova. There are no primordial heavy elements from the big bang, there are no other processes known which will produce these elements. That's everything above iron, including copper, silver, iodine, gold, mercury, lead, uranium, and plutonium, among others. Some of those are produced by radioactive decay from heavier elements which were produced in a supernova, but a supernova is the ultimate origin.

As the collapse continues, a density is reached where all atoms are dissociated into nuclei and electrons, then forcing the "elementary particles" electrons and protons to combine, which produces a neutron and a neutrino. The nuclear strong force prevents neutrons from being compressed into each other, and the core reaches its maximum density, which is basically the density of atomic nucleus. The core of the star is all neutrons and one big nucleus.

However, this density can be thought of as a barrier which all of the core had been rushing toward at great speed, a fraction of the speed of light. That's a bunch of kinetic energy, and it hits this "wall" and rebounds. This produces an enormous shock wave of material. (Any atoms which haven't been dissociated will be dissociated by the shock wave, which absorbs some of its energy. In some cases, the shock wave can stall because of this.)

Recall that neutrons and neutrinos are being produced. Neutrinos are famously elusive particles. They have extremely low mass, and they have no electric charge. Because of this, the have almost no interaction with other matter. Neutrinos whiz right through the entire Earth as if it weren't there. It is extremely rare for them to actually hit something.

Amazingly, none of what's happened prior to this point is visible outside of the surface of the star. The core collapse involves primarily the core, and the core's density is so great that none of the energy released has been escaping outside the core. (Indeed, in a normal star as it normally shines, photons produced in the interior will take many years to reach the surface of the star, because they bounce around in the dense environment.)

Now, those neutrinos represent a huge release of energy, and most of them will be absorbed by the outer core because, remember, this has been approaching a density equal to the nucleus of an atom. If the earlier shock wave had stalled, this will re-energize it. If not, it will add to it. The outer layers of the core, and the outer layers of the star, will be blown away by the force of this shockwave.

A small portion of those neutrinos, which nevertheless is still an enormous number of neutrinos, will pass through the outer core and the outer layers and will sail out into the void ahead of both the light of the supernova, and the shock wave. This neutrino burst will be the first evidence of the supernova, if you have the equipment to detect it. It will last about ten seconds.

For a 25 solar mass star, what will remain will be a neutron core, what's called a neutron star. It will be a tiny star in size, but still very large in mass, still more massive than the Sun, though having had a fair amount of its original mass converted to energy or blown into space. However, it will occupy a sphere only miles in diameter, maybe 15 miles, or so.

This neutron star will retain the magnetic field of its progenitor and, importantly, also its angular velocity. Like an ice skater who pulls her arms inward, because much of the mass of the star is retained in the neutron core, and the core has shrunk down to a very small size, a relatively stately rotation of the progenitor star becomes an extremely rapid rotation of the neutron star, with rotation rates measured in milliseconds. And because it's retained its magnetic field, and it, too, has been compacted but without losing its strength, and because the magnetic field need not be oriented the same as the rotation, particles accelerating into the gravity well of the neutron star can produce a rotating beam of radio waves aimed away from the poles of the magnetic field. A listener on Earth will hear a pulse equal to the rotation rate. These are known as pulsars.

If a neutron star isn't a pulsar, or isn't a companion of another star, it's not likely that we'll be able to see it, because they mostly don't "shine". They do emit energy, but not like a star which is burning nuclear fuel. However, if you were nearby, you might notice one because its intense gravitational field will bend light around it, and would act as a noticeable lens for viewing distant object. The x-rays would also be a clue.

Meanwhile, as a result of the supernova, a huge amount of energy has been spewed out into space in all directions. Gamma rays, and other light of all energies. Also, matter, the neutrinos that have been mentioned, neutrons and alpha particles and from the outermost layers and the corona, hydrogen and helium at an exceptionally high speeds. Both the electromagnetic radiation and the matter will speed outward in an expanding shell. For anything living nearby, this will be deadly.

However, if there are nebulae (clouds of light elements, some of which might themselves be the remnants of earlier supernovae) nearby, within a few dozen light years, this shock wave can cause densities and energies to increase, inciting star formation. This is one of the ways, possibly the primary way, that new stars are formed.

So against the background of these vast distances and vast expanses of time, we see that supernovas are events that happen within a matter of moments, in an unimaginably violent explosion of extravagant energy.

Yet so much of the universe we know, and which is most important to us, relies upon supernovas. All the heavier atoms, many of which make up the world around us and are necessary for life, originated in supernovas. Many stars, probably our own Sun, were kindled into life by a nearby supernova, the heavier elements they contain (everything heavier than helium) having originated in an earlier supernova. The universe began with hydrogen and helium, nothing more.

Life begins in the supernova.
posted by Ivan Fyodorovich at 9:20 PM on January 22 [68 favorites]


"A small portion of those neutrinos, which nevertheless is still an enormous number of neutrinos..." should be "A large portion of those neutrinos..." Also the corresponding "most" should be "some" in the previous paragraph. Whoops. I knew that, but I got confused by something and went against my own judgment. Er, and "angular velocity" should be "angular momentum". Dammit.
posted by Ivan Fyodorovich at 10:19 PM on January 22 [3 favorites]


aramaic: A lot of evidence is building up that many, and quite possibly all, Type Ia's come from white dwarf/white-dwarf collisions rather than the accretion-from-a-red-giant-companion picture typically taught in Astro 101 courses (and discussed above). One of many factors in this has been the development of models where supernovae can occur in collisions with total mass below the electron degeneracy pressure limit (also known as the Chandrasekhar limit) -- i.e., the Astro 101 picture is just wrong. Another example is that no one's found a red giant in pre-explosion images of where 2011fe (the supernova in M101 mentioned above) went off, and one should have been detected if it was there. In a double-white-dwarf system, there's even less possibility of there being any life when the supernova happened, as both stars have burnt out.

Plenty of Ia's occur in galaxies with recent star formation, so that wouldn't be a concern regardless of the particular history of M82 -- for some years now, the accepted picture has been that there is a 'prompt' set of Ia's that lag star formation by only a few hundred million years (long enough for some white dwarfs to form), as well as a 'delayed' population that trickles in over billions of years; this allows you to explain the SN Ia rates in both highly-star-forming and non-star-forming galaxies simultaneously (this has led to some speculation that one of these populations might correspond to the double-white-dwarf cases, and the other to the white dwarf + red giant cases). More recently, it's been argued that in fact you only need one population of supernovae, with an Ia rate that simply declines as a power law (i.e., a rate proportional to 1/(time since star formation) ) after a stellar population is formed.
posted by janewman at 11:53 PM on January 22 [3 favorites]


Here's the story of University of London Observatory undergraduates discovering the supernova. They happened to be photographing M82 as a learning exercise at the right time. "One minute we’re eating pizza then five minutes later we’ve helped to discover a supernova."

One thing that fascinates me about astronomy is how we know all this stuff. Take Ivan Fyodorovich's lovely poetic description of neutron. It's also all happening at distances, time scales, sizes, masses, and energies way, way beyond human access or comprehension. It's a triumph of the scientific method that we can talk with confidence about things like this, so far from our direct experience. And it is indeed magical that the final event is a bright dot you can see with just a little help, a candle burning for two weeks.

Me, I can't wait to hear if any neutrino detectors saw it.
posted by Nelson at 9:06 AM on January 23


Ivan Fyodorovich: That. Was. Awesome.
posted by odinsdream at 9:18 AM on January 23 [2 favorites]


A somewhat pedantic footnote to Ivan's explanation: only a portion of the heavy elements actually form in supernovae (massive stars generate many of them via neutron capture, commonly known as the s-process) . Supernovae help distribute them, though. (One other update -- astronomy progresses quickly! -- the picture of supernova-triggered star formation Ivan refers to has fallen out of favor over the last couple of decades, turbulence in cold gas clouds seems to be much more important).

Regardless, this underlies Carl Sagan's famous quote that "We're made of star-stuff". Without dying stars, we wouldn't be here.
posted by janewman at 9:59 AM on January 23 [5 favorites]


Nelson, I would be very very surprised (in a happy way!) if we saw any neutrinos from this for two reasons. Mostly because Type Ia's produce far fewer neutrinos than core core-collapse supernovae. The Iron/Nickel atom to degenerate neutron conversion produces something like one neutrino per proton converted at collapse while the Ia's really don't really have an equivalent process. Also, the ~4Mpc distance to the host galaxy is sort of in the weeds as far as detection thresholds go.
posted by McSwaggers at 10:04 AM on January 23 [1 favorite]


Wow, what a great article by Ivan Fyodorovich. Very informative, and in some strange way it's very romantic to think of the elements of our lives being born in the cataclysmic explosion of a distant supernova.

And just think, the shock wave from the M82 supernova could be reaching out to some vast, empty, dead nearby nebula of dust and gas, and lighting a spark that will, in millions of years, lead to the creation of a new star, a new system, and a new planet. And a billion years after that, what strange creature on that not-yet-created planet will lift her eyes to the sky and wonder at the bright supernova in a distant galaxy that heralds the end of our civilization, the very civilization that witnessed the conception of her own star?

The mind reels.
posted by math at 6:10 AM on January 24 [1 favorite]


Lots of observations for the next few weeks to follow. I'm not familiar with this field or its online communications, but I did a bit of searching around and found some interesting things, many of which should update over time: If any astronomy Mefites are looking for a post topic, I think the way new astronomical observations are communicated is fascinating but don't know enough to explain it. Particularly how priority of discovery is established and the interaction between amateurs and professionals. I found my way to telegrams of followup observations of SN 2014J but I couldn't find the official discovery communication that establishes Fossey at UCL as the formal discoverer.
posted by Nelson at 9:18 AM on January 24


Nelson, most of the action on transients happens via one of two sets of electronic notices these days, Astronomer's Telegrams (ATels) and GCNs. For historical reasons, most gamma ray burst discussion starts on GCNs (I had to look up what GCN stood for: Gamma-ray Coordination Network), while almost everything else goes on ATels. (IAU telegrams are not particularly common, probably because they are more official in nature?)

ATel 5786 is the first announcement that I know of for this supernova, and it mentions Fossey: At UT 2014 Jan 22.305, we obtained a spectrum of PSN_J09554214+6940260 (discoverer: S. J. Fossey) with the Dual Imaging Spectrograph on the ARC 3.5m telescope. We classify this as a Type Ia supernova [...] The best superfit match is SN2002bo at -14d.

What's more interesting is the amount of rapid response science that happened / is happening on the professional astronomers group on Facebook, of all places, and the rapid information flow via Twitter. Turns out X-ray astronomers tweet first, while optical experts turn to Facebook. I'm sure sociologists will have a wonderful time with science in the age of social media.
posted by RedOrGreen at 10:55 AM on January 24 [3 favorites]


Thanks for the answer, RedOrGreen! But ATel 5786 just raises a question; how did Fossey communicate and establish priority on his observation? The ATel is the spectograph that proves it's a supernova, why does Fossey's visual observation count as the "discovery"? I'm wondering if the clue is in CBET 003792 from this archive. But it requires a Harvard login.

It's unseemly to mention, but there's a sort of race to be the first to observe phenomena like this. Various folks looking back had images of SN 2014J well before Fossey's own observation. But Fossey's report is the one credited as discovery, I imagine because he was the first to have a good guess as to what he saw. I think I also read one early report crediting L. Elenin (Lyubertsy, Russia) and I. Molotov (Moscow, Russia) with the discovery.
posted by Nelson at 11:38 AM on January 24


Oh, I see what you're getting at. The norms of how things are "supposed" to work are rapidly changing, but as far as this event is concerned, it looks like Fossey went the official route, reporting the discovery to the IAU Central Bureau for Astronomical Telegrams.

The IAU gets to bless the official designation (SN2014J), so you're right, CBET 3792 establishes him as the discoverer.

But the reason so much work started on it so quickly (and certainly the reason I knew about it before Facebook) is ATel 5786 referenced above. That comes down to contacts - the article says, "[Fossey] also alerted a US-based supernova search team who have access to spectroscopic facilities."
posted by RedOrGreen at 12:28 PM on January 24 [2 favorites]


ATel and GCN have emerged over the last 10-15 years because IAU telegrams are slower to get out (the disadvantage of the vetting they go through). Informal networks can still be faster; I ended up being a coauthor on a couple of major gamma ray burst papers because I happened to be observing at Keck when they were discovered, and we got calls from people working on GRBs urgently asking us to collect data.

Nelson: people are looking for earlier images not to get credit for discovery -- that's based on who notices the event, not who collected the earliest photons. [I'm sure, though, that whoever ends up having seen it the earliest will end up putting out a press release, as press officers like superlatives of any sort (highest redshift, most luminous, etc.] Instead, we want early images for the information they provide. We have very little information on how quickly supernovae get brighter in the first day (as of course they're hard to discover before they've gotten bright) -- the denser time sampling we can get in that crucial period, the more we will learn.
posted by janewman at 12:38 PM on January 24 [3 favorites]


So, uh, as someone who has written a bunch of ATEL's, CBET's, and GCN's, heres how it generally works:

The first thing to remember is that this is all transient science. So, a lot of astronomy observations are in no particular hurry. Many stars, galaxies, and other objects change very slowly because of the mass and sizes involved, and so weeks, months, or years between objects may represent changes that are miniscule or undetectable. Phenomenon which change very rapidly we call transients, and the various groups involved in observing them have set up methods of dealing with these atypical astronomical observations.

The most important of which recently has been how the internet has enabled near instantaneous reporting of these kinds of objects, so that once such an object has been discovered other peoples telescopes can start looking at that object within minutes. This has essentially helped launch a revolution in transient science in the last twenty years, along with enabling factors such as robotic telescope surveys and cheaper computing power/data storage.

So, GCNs, ATELs, and CBETs are 3 different flavors of transient object reporting mechanisms.

GCN's are not really for supernovae - their for Gamma Ray Bursts (GRB) primarily, and occasionally other X-Ray transients are reported on these as well. Historically this network came about for the detection and reporting of GRBs with other wavelengths providing followup supporting observations (UV, Optical, IR, Radio). Now, this is a little murky because Gamma Ray Bursts also sometimes have a supernovae associated with them (like a dozen ever out of many hundreds) but this is always much later than the GRB (week(s)) and is usually just announced on their, and directs people to CBETs/ATELs. The way to think of GCN's is that they are mostly-GRB or X-ray transient specific versions of CBETs and ATELs which are more general. So, a GCN is issued when a GRB is discovered most often by the satellites Swift or Fermi, and then followup ones are issued when other teams observe and report these.

CBETs and ATELs. CBET= Central Bureau for Astronomical Telegrams, and ATEL=The Astronomer's Telegram. These are more general purpose purpose, and historically come from optical and IR astronomers. They cover a much larger variety of objects! Including nearby objects (comets, minor planetoids), near-ish galactic objects (novae, Cataclysmic variables, tons of others) and of course extra-galactic objects, including my favorite - supernovae.

The relative use of CBETS and ATELS have evolved dramatically over time, but today the way it typically works is this: ATELs are very quickly reported and distributed, so initial observations of a *probable* supernovae are reported here, as are a bunch of subsequent followup observations as people point their telescope at it. Once a probable supernovae is reported the International Astronomical Union (IAU) who runs the CBETs and assigns supernova names, gives the object a PSN J+a bunch of numbers name. Here, PSN = Possible Supernova, J=J2000=a coordinate system that we use for locating objects, and the bunch of numbers are its position (Right Assention, Declination) in that coodinate system. We sometimes colooquially refer to names like this that are essentially just positions as telephone numbers.

Ok, great, so we have a PSN object and people are taking a bunch of observations of it. Once enough observations have happened that we are confident that this object is really a supernovae, this is usually means initial photometric brightness observations (regular pictures, essentially) and a spectra, the IAU puts out a CBET with everybody who took the observations as coauthors and the CBET itself summarizes the observations and lists the name. The observations summarized in these are typically observations that have also been reported more quickly in ATELS, but it serves as serves as a more formal discovery record.

The way that the discoverer is listed is that it is *usually* whoever notices the new object and claims that its a supernovae, putting out the first ATEL. In the case of amateur astronomers discovering a supernovae, very often they will let other dedicated transient search teams know so that they can begin looking at it. These transient search teams will often write the ATEL itself, but acknowledge the amateur astronomer as discovery and report his observations/measurements. More dedicated supernovae searching amateur astronomers may write their own ATEL/IAUCs. Often times people will realize that they have fortuitous observations of the transient pre-'discovery' and they will be reported. These observations do not get to claim 'discovery' credit, rather they are published for a more generally complete picture of the object.

So, uh, CBET 3792 I am probably not allowed to post in general on the web, but individually is probably fair use for this sort of public outreach. Memail me if you want a copy to see how this one worked.
posted by McSwaggers at 12:46 PM on January 24 [7 favorites]


KAIT pre-discovery detection of SN 2014J in M82. Nice image sequence.

"The student checkers unfortunately didn't notice the new object in the prediscovery images. We have asked them to check more carefully in the future."

Oh, burn... (That's a really poor way to treat undergraduate volunteers.)
posted by RedOrGreen at 11:39 AM on January 28 [3 favorites]


Eyeballing that brightness graph, the supernova looks to have reached peak brightness a couple of days ago at about 10.5. Not quite bright enough for regular binoculars, but plenty for a small telescope. I'm hoping to finally get a chance to see it this weekend.
posted by Nelson at 1:43 PM on February 4


Ancient Star May Be Oldest in Known Universe
posted by homunculus at 6:45 PM on February 11


"Ancient Star May Be Oldest in Known Universe"

Such a bad way to present this. It's the oldest star we've observed. That it's only 6,000 light years away pretty much means that stars like this are common, we'll find more of them just in our neighborhood.

The significance is that we've found a very early-generation star and its composition gives us more information on what the stars which preceded it were like. Per my earlier comment, the heavier elements are generated in stars, there were (essentially) no elements other than hydrogen and helium produced in the Big Bang, so the heavier elements were produced by generations of stars with successive generations having larger proportions of the heavier elements. They're disbursed by supernovae and become part of new stars and (negligible in mass relative to the stars, but important to us) all the others stuff, like comets and planets and asteroids and nebulae and stuff just scattered (very sparsely) in the interstellar environment.

Some stars like this one, because of their mass and composition, can live very, very long and so they are effectively living fossils. Other stars, because of their mass and composition, have very short lives, and so they're recent. So the sky is full of stars which variously represent different eras of the evolution of the universe with regard to the composition and formation of stars. This provides astronomers with pretty good data to use in their models of stellar evolution, but things are pretty fuzzy about what happened in the early universe with star formation and evolution and so these oldest stars provide important data.
posted by Ivan Fyodorovich at 8:51 AM on February 12


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