Nearby Galaxy M82 Hosts a New Supernova(slate.com)
slate.com
Nearby Galaxy M82 Hosts a New Supernova
http://www.slate.com/blogs/bad_astronomy/2014/01/22/kaboom_nearby_galaxy_m82_hosts_a_new_supernova.html
44 comments
My understanding is that there are three competing theories which have the strongest claim on explaining Type Ia supernovae. The classic theory is that a non-white dwarf companion star feeds material onto a white dwarf, which increases its mass. This kicks off a complicated chain of events, some of which may occur over timescales of a thousand years, ultimately culminating in the initiation of fusion reactions (initially Carbon, then Oxygen) in the core of the white dwarf. The fusion reactions release heat, but because the white dwarf is already under electron degeneracy conditions it is unable to increase pressure and expand to moderate the fusion reactions, so instead they are caught in a very strong positive feedback loop. In a matter of seconds the fusion reactions consume all of the Carbon in the star and then begin consuming the Oxygen in the inner core, this process releases more than enough energy to completely unbind the star gravitationally, the star explodes in a supernova. Alternately, it's also possible that a white dwarf star could have more than enough mass to undergo a Type Ia explosion but is kept in check by rapid spinning. As the star ages and the spinning slows down it crosses a boundary where the above events occur. Or, two white dwarfs could instead merge with each other.
It's actually likely, in my opinion, that all three models contribute to Type Ia events in nature, but it's currently unknown which variety is the most common cause of such supernovae.
It's actually likely, in my opinion, that all three models contribute to Type Ia events in nature, but it's currently unknown which variety is the most common cause of such supernovae.
[deleted]
"Given the fact that it’s nearby, up high for so many observers, and caught so early, this may become one of the best-observed supernovae in modern times."
"[...] But the good news is it appears to have been discovered about two weeks before it hits peak brightness. Supernovae get brighter over time before fading away, and this one may get as bright as 8th magnitude, which is within range of binoculars."
"[...] But the good news is it appears to have been discovered about two weeks before it hits peak brightness. Supernovae get brighter over time before fading away, and this one may get as bright as 8th magnitude, which is within range of binoculars."
Its very sad to think about all the aliens living in or around the M82 galaxy. I hope they managed to invent inter-galactic space travel in time to escape to another solar system safely. God bless them.
It may be sad for any aliens living around the star itself and nearby solar systems. The rest of the galaxy won't feel a thing.
This is not the 'Star Trek' movie where, for some weird reason I'll never understand, a supernova was a catastrophic event, for civilizations with FTL travel.
If our own sun turned into a supernova (not possible btw), the nearby star wouldn't even see that for about 4 years, best case. And that would be just the radiation, matter would take hundreds, if not thousands of years to get there. So it is not like they wouldn't have any warning.
And that's for the closest star.
This is not the 'Star Trek' movie where, for some weird reason I'll never understand, a supernova was a catastrophic event, for civilizations with FTL travel.
If our own sun turned into a supernova (not possible btw), the nearby star wouldn't even see that for about 4 years, best case. And that would be just the radiation, matter would take hundreds, if not thousands of years to get there. So it is not like they wouldn't have any warning.
And that's for the closest star.
On the contrary, if you consider that supernovae make our version of life possible, maybe life will happen someday at M82 because of this explosion.
We are all supernova dust, after all.
We are all supernova dust, after all.
You mean another galaxy, assuming the supernova would create inhospitable conditions throughout all of M82.
I'm pretty sure that 99% of that galaxy didn't feel a thing. The size of m82 is 40000ly and a largest supernovae will affect( not necessarily destroy stuff ), 3000ly around itself.
Relevant: http://en.wikipedia.org/wiki/Near-Earth_supernova
Relevant: http://en.wikipedia.org/wiki/Near-Earth_supernova
A supernova is a big explosion, but I don't think it's quite 'galaxy sanitizing' big.
An appellation reserved for gamma ray bursts (and only within the emission cones).
http://what-if.xkcd.com/73/
A nearby supernova would definitely be sterilizing to the kind of life found on Earth, and to a lot of other imaginable forms. Of course, "nearby" in astronomical terms is sometimes unintuitive. :-)
A nearby supernova would definitely be sterilizing to the kind of life found on Earth, and to a lot of other imaginable forms. Of course, "nearby" in astronomical terms is sometimes unintuitive. :-)
Old news. that happend 12,000,000 years ago...
People always say this sort of thing when talking about distant events, it's not actually true.
When we're talking about long distances then the relativity of simultaneity comes into play strongly. There is no universal ordering of events, there is a substantial degree of relativity to ordering of events that are separated by great distances. And, in fact, the only hard boundaries on this ordering are the "light cones" connecting events. In one reference frame the M82 supernova could have happened 12 million years ago, in another reference frame it could have happened a year ago, or two years ago, or even 20 million years ago. In the reference frame of any neutrinos that happened to have been created in the supernova it would have occurred mere seconds or hours before the first light reached Earth.
When we're talking about long distances then the relativity of simultaneity comes into play strongly. There is no universal ordering of events, there is a substantial degree of relativity to ordering of events that are separated by great distances. And, in fact, the only hard boundaries on this ordering are the "light cones" connecting events. In one reference frame the M82 supernova could have happened 12 million years ago, in another reference frame it could have happened a year ago, or two years ago, or even 20 million years ago. In the reference frame of any neutrinos that happened to have been created in the supernova it would have occurred mere seconds or hours before the first light reached Earth.
It doesn't really make sense to talk about points in time in reference frames other than ours.
Heh. It depends on how you interpret relativity I think.
Man these Samsung phones just keep getting bigger and bigger.
[deleted]
“And just to get this out of the way, we’re in no danger from this explosion. It’s far too far away.”
Also, it happened 12 million years ago, so I think we are pretty safe.
Also, it happened 12 million years ago, so I think we are pretty safe.
Unfortunately there is no inverse square law for time, only for distance. So if it is large enough, regardless of how long it takes to get to us, we'd be just as toasted. You get sun burns when you are out too long, even though that was so like 8 minutes ago. :-)
That said, it also means we can probably skip that half of galaxy M82 in our search of extraterrestrial intelligence. For the planets that were within a few light years of the supernova, they probably lost anything that wasn't bolted down in terms of atmospheric gases :-).
That said, it also means we can probably skip that half of galaxy M82 in our search of extraterrestrial intelligence. For the planets that were within a few light years of the supernova, they probably lost anything that wasn't bolted down in terms of atmospheric gases :-).
How is this an argument? If I shoot a bullet from a very distant planet and it will reach Earth after 12M years, will you be safe if it came directly towards you?
An explosion is no way similar to a bullet, like comparing laser to a light bulb. The energy or rays gets dispersed over distance.
I think you misunderstand the point of gabipurcaru's analogy. nmc's confusion was about time, not energy dispersion. That is, nmc indicated that we would somehow be safe because the explosion happened 12 million years ago. But gabipurcaru pointed out how long ago something happened is irrelevant if the energy that reaches you is high enough.
You are correct that we are safe because of energy dispersion - or, put another way, because it is 12 million light-years away. But nmc thought we were safe because it was 12 millions years ago, and gabipurcaru tried to show by analogy why that is not true.
You are correct that we are safe because of energy dispersion - or, put another way, because it is 12 million light-years away. But nmc thought we were safe because it was 12 millions years ago, and gabipurcaru tried to show by analogy why that is not true.
Lasers or light bulbs, photon density (flux) follows the inverse square law.
EDIT: For the follow-up questioning the correctness of my comment:
https://en.wikipedia.org/wiki/Inverse_square_law#Light_and_o... https://en.wikipedia.org/wiki/Radiative_flux
EDIT: For the follow-up questioning the correctness of my comment:
https://en.wikipedia.org/wiki/Inverse_square_law#Light_and_o... https://en.wikipedia.org/wiki/Radiative_flux
I believe this is incorrect, anyone can confirm?
Surely after 12M years, the bullet will have rusted to dust in-flight? :)
No, it would have been perfectly preserved, hanging motionless in a dry vacuum. Archivists would be envious.
Speaking of archivists:
http://sci.esa.int/rosetta/31242-rosetta-disk-goes-back-to-t...
http://blog.longnow.org/02009/05/21/what-13500-pages-micro-e...
(this is the object of yesterday's HN story https://news.ycombinator.com/item?id=7092313)
Speaking of archivists:
http://sci.esa.int/rosetta/31242-rosetta-disk-goes-back-to-t...
http://blog.longnow.org/02009/05/21/what-13500-pages-micro-e...
(this is the object of yesterday's HN story https://news.ycombinator.com/item?id=7092313)
Oh I know, just kidding :)
Not enough oxygen for it to rust. And even if it were, a collection of dust traveling at bullet speeds would still probably kill you.
But worry not! A bullet fired from 12 million light years away would probably be ablated into nothing by the interstellar dust.
But worry not! A bullet fired from 12 million light years away would probably be ablated into nothing by the interstellar dust.
Nope.
Stop and think about the fact that starlight can travel that distance. Therefore the accumulated dust along that path is not enough to block light. That little dust won't stop a bullet either.
Stop and think about the fact that starlight can travel that distance. Therefore the accumulated dust along that path is not enough to block light. That little dust won't stop a bullet either.
But it's not just starlight - it's the light of a whole nova (and the collective light of a whole galaxy.)
I can see starlight from the bottom of a pool, but the water in the pool will still stop a bullet.
(I am not a scientist, I could be entirely wrong, but it seems like the collective dust of 12 million light years would surely ground down a bullet, while being intermittent enough to let starlight pass through in aggregate.)
I can see starlight from the bottom of a pool, but the water in the pool will still stop a bullet.
(I am not a scientist, I could be entirely wrong, but it seems like the collective dust of 12 million light years would surely ground down a bullet, while being intermittent enough to let starlight pass through in aggregate.)
Well let's calculate it. According to http://www.universetoday.com/30280/intergalactic-space/ there is about 1 hydrogen atom per cubic meter. According to https://www.google.com/search?q=light+year+in+meters&ie=utf-... there are about 10^16 meters in a light year. So 12 million light years is about 10^23 meters. Avagadro's number is about 6 * 10^23. So a tube a square meter across is a bit under 0.2 moles of hydrogen. According to http://answers.yahoo.com/question/index?qid=20080619205711AA... at standard air pressure a mole of hydrogen would be about 22 liters, so we're talking about 4 liters of gas at standard pressure. Which would be about 1 square meter across, and 4 millimeters tall.
The collective dust of 12 million light years of intergalactic space does not seem likely to grind down a bullet very much.
That said, the whole calculation is flawed because first you have to get out of our galaxy, which is much higher density. Though that also wouldn't stop a bullet. But then you have our atmosphere, and that most definitely would destroy a bullet that tried to pass through it!
But the moral remains. Space is empty. Really empty. Unimaginably so.
The collective dust of 12 million light years of intergalactic space does not seem likely to grind down a bullet very much.
That said, the whole calculation is flawed because first you have to get out of our galaxy, which is much higher density. Though that also wouldn't stop a bullet. But then you have our atmosphere, and that most definitely would destroy a bullet that tried to pass through it!
But the moral remains. Space is empty. Really empty. Unimaginably so.
What affect would expansion of the universe have on the bullet? Would it just be a little longer and pointier?
More likely, it will have reached its apoapsis and fallen back on your planet, unless you have one hell of a gun...
How long ago it happened is irrelevant. It really is just the distance that is keeping us safe.
Awesome! How often do astronomers catch supernovae like this?
Fairly often. There are a couple ways that supernovae get spotted. Sometimes an amateur astronomer will find a supernova, there are lots of folks who actually do this as a hobby and surprisingly it's something that such folks can actually be fairly productive about, but it requires a lot of work. Also, there are various ongoing sky surveys of various sorts including asteroid detection programs which typically pick up supernova at a fairly regular rate merely due to being able to observe a huge number of galaxies in any given night (since supernovae are typically bright for periods of many days to weeks). Additionally, we've deployed a variety of satellites that have "transient detectors" designed to look for the signs of gamma ray bursts but also capable of detecting ordinary supernovae, sometimes.
For example, in 2013 over 230 supernovae were discovered. And currently there are about 3 dozen active supernovae that can be viewed with a telescope, but most of them are fairly dim in very distant galaxies and would require a fairly sizable telescope to be able to see (~300mm aperture or so). The M82 supernova is the only one that is currently visible with an ordinary backyard telescope or binoculars.
For example, in 2013 over 230 supernovae were discovered. And currently there are about 3 dozen active supernovae that can be viewed with a telescope, but most of them are fairly dim in very distant galaxies and would require a fairly sizable telescope to be able to see (~300mm aperture or so). The M82 supernova is the only one that is currently visible with an ordinary backyard telescope or binoculars.
How often do they catch supernovae in general? Really often apparently: http://www.cbat.eps.harvard.edu/lists/Supernovae.html
If you mean like the 8th magnitude that this article says it could reach, then the last one to come close (and surpass it by far) was 1987A (http://en.wikipedia.org/wiki/SN_1987A) at 4.5 magnitude (I remember hearing about that when I was a kid). 1972E was 8.5. 1954A was 9.8. 1937C was 8.4. 1895B is listed as 8.0. 1885A at 5.8. There are some negative magnitude ones listed at the end of the list (1006, 1054, 1572, 1604) which were within the Milky Way. (There are wikipedia articles about those supernovae and older ones as well.)
If you mean like the 8th magnitude that this article says it could reach, then the last one to come close (and surpass it by far) was 1987A (http://en.wikipedia.org/wiki/SN_1987A) at 4.5 magnitude (I remember hearing about that when I was a kid). 1972E was 8.5. 1954A was 9.8. 1937C was 8.4. 1895B is listed as 8.0. 1885A at 5.8. There are some negative magnitude ones listed at the end of the list (1006, 1054, 1572, 1604) which were within the Milky Way. (There are wikipedia articles about those supernovae and older ones as well.)
This is important because the so-called single-degenerate model in which a red giant dumps material onto the white dwarf is expected to produce very faint hydrogen lines. Observing these hydrogen lines in the spectrum would be a smoking gun for the single degenerate model. On the other hand, if they are not observed, it would put very tight constraints on how the single degenerate model could work.
Another reason these observations will be useful is that head-on collisions between white dwarfs are expected to produce two separate explosions with different velocities -- this then produces double peaks in the spectral lines [1]. Sometimes these are hard to observe because the SNe are so far away, however. They will be most easily observable in this SN. If they're found it would be a smoking gun for a head-on collision between two white dwarfs.
[1] http://arxiv.org/abs/1401.3347