APOD: Supernovae in the Whirlpool (2011 Jun 11)

[APOD Robot]

Supernovae in the Whirlpool

Explanation: Where do spiral galaxies keep their supernovae? Near their massive star forming regions, of course, and those regions tend to lie along sweeping blue spiral arms. Because massive stars are very short-lived, they don't have a chance to wander far from their birth place. Remarkably, in the last 6 years two Type II supernovae, representing the death explosions of massive stars, have been detected in nearby spiral M51. Along with a third supernova seen in 1994, that amounts to a supernova bonanza for a single galaxy. As demonstrated in these comparison images, SN2005cs, the supernova discovered in 2005, and more recently SN2011dh, the exceptionally bright supernova first recorded just last month, both lie along M51's grand spiral arms. Perhaps the original spiral nebula, M51 is also known as the Whirlpool Galaxy.

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[mexhunter]

Few documents like this comparison between the two events, with six years between them.
Excellent!
Greetings
César

[Ann]

That's a fantastic APOD!

The two images of M51 gives a great insight into the kind of stellar environment that produced the two supernovae, both of type II (that is, they were produced by very massive stars that ran out of fuel in their cores). If you look at the image on the left, the one with the SN2005cs supernova, you can see the part of the galaxy that would produce the SN2011dh supernova six years later. This "pre-supernova" area looks like roundish patch which is bluer in color than its surroundings.

To the right of this patch, in the "inter-arm" region of the galaxy, the color of the stellar population is brownish, characterized by low-mass stars that can't produce Type II supernovae.

To the left of the patch, the color of the stars is generally blue, but a more muted blue than the blue patch, characterized by an intermediate population of stars, whose high-mass stars have already died, possibly by exploding as supernovae.

Above and, in particular, below this patch, there are pink star formation regions. Here there are very massive stars, but they are so young that they haven't had time to run out of fuel and explode as supernovae.

But in the blue patch, star formation has ceased, and the massive stars are just about to run out of fuel. Only six years after the image on the left was taken, one of the blue stars in that patch blew its top! (Note, by the way, that the supernova appears to sit smack in the middle of this blue patch, perhaps where the concentration of "supernova-ripe" massive stars is the highest.

What about the part of the galaxy where the 2005 supernova exploded? We can look at that part of the galaxy in the 2011 image of M51. The part of the galaxy that produced SN2005cs is not as blue as the blue patch that produced SN2011dh. My guess is that there are fewer "supernova-ripe" stars in the general area of SN2005cs than in the general area of SN2011dh. But that doesn't mean that there can't be a few massive oddball stars there that are just the right mass and age to explode.

Ann

[ddale51]

Kaboom! I can only imagine what such a massive explosion does to the surrounding galaxy neighbors. I know stars are really far apart even in dense spiral arms, but some of those local stars must have taken a beating when that nova blew up. Does it blow away some of the stars' mass? Does it affect the trajectory of these stars, jostling them into a different orbital path around the galaxy nucleus? I'm glad I don't live on a nearby planet!

[orin stepanek]

I thought! Didn't I just see this? http://apod.nasa.gov/apod/ap110611.html But it was a similar picture showing one of the super novas. http://apod.nasa.gov/apod/ap050719.html

[neufer]

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[rguyg]

So how away is the whirlpool? I guess that is a loaded question.

As we don't know how fast we are moving away from M51 or do we, how close we were at the time of the supernova, and the rate that we are accelerating.
What else am I missing? Is there an approximation?

[Joe]

Isn't it premature to say that that it's a bonanza in M51 because of 3 supernovae in 17 years? There are more scopes looking into the sky everyday so it stands to reason that we'll see more and more.

[neufer]

So how away is the whirlpool?

31 million light-years.

[Chris Peterson]

Kaboom! I can only imagine what such a massive explosion does to the surrounding galaxy neighbors. I know stars are really far apart even in dense spiral arms, but some of those local stars must have taken a beating when that nova blew up. Does it blow away some of the stars' mass? Does it affect the trajectory of these stars, jostling them into a different orbital path around the galaxy nucleus? I'm glad I don't live on a nearby planet!

Not even close. The only effect a nearby supernova might have would be to raise the radiation environment- potentially to dangerous levels if it is near enough, and the conditions are right.

[Chris Peterson]

Isn't it premature to say that that it's a bonanza in M51 because of 3 supernovae in 17 years? There are more scopes looking into the sky everyday so it stands to reason that we'll see more and more.

No. We've been watching galaxies for over 100 years, and many have been under near continual surveillance. Our knowledge of the statistics of supernovas in various kinds of galaxies is quite good. Three in that period in a single galaxy either means something odd is going on there, or more likely, we're just seeing a statistical outlier (which is itself statistically likely given the number of galaxies we observe).

[NoelC]

Lovely imagery, R. Jay Gabany!

Remarkably, in the last 6 years two Type II supernovae, representing the death explosions of massive stars, have been detected in nearby spiral M51. Along with a third supernova seen in 1994, that amounts to a supernova bonanza for a single galaxy.

One learns, in statistical analysis, that in the real world "things happen in clumps".

-Noel

[rstevenson]

... We've been watching galaxies for over 100 years, and many have been under near continual surveillance. Our knowledge of the statistics of supernovas in various kinds of galaxies is quite good. Three in that period in a single galaxy either means something odd is going on there, or more likely, we're just seeing a statistical outlier (which is itself statistically likely given the number of galaxies we observe).

Odd. I could swear that very recently someone here at the Asterisk* explained that there is no significance at all in the timing of these supernovae, that in fact they may have occurred hundreds of years apart, if not thousands, in their galaxy and that we're only coincidentally seeing them this close together in time from our particular point of view. So how could "something odd [be] going on there"?

Rob

[neufer]

... We've been watching galaxies for over 100 years, and many have been under near continual surveillance. Our knowledge of the statistics of supernovas in various kinds of galaxies is quite good. Three in that period in a single galaxy either means something odd is going on there, or more likely, we're just seeing a statistical outlier (which is itself statistically likely given the number of galaxies we observe).

Odd. I could swear that very recently someone here at the Asterisk* explained that there is no significance at all in the timing of these supernovae, that in fact they may have occurred hundreds of years apart, if not thousands, in their galaxy and that we're only coincidentally seeing them this close together in time from our particular point of view. So how could "something odd [be] going on there"?

Point taken, Rob.

If the supernovae in M51 were, in fact, induced by NGC 5195:
http://asterisk.apod.com/viewtopic.php? ... 33#p149933
http://asterisk.apod.com/viewtopic.php? ... 54#p124054

then the increased rate of supernovae production would have to occur over an extended period of many tens of millions of years;

which is (no doubt) why Chris strongly prefers the statistical outlier answer.

(But I will let him speak for himself.)

[J.Stteele]

I know the picture is Stuning And All But i wish they had zoomed in on the centre, because it looks quite rough in there.

[Chris Peterson]

Odd. I could swear that very recently someone here at the Asterisk* explained that there is no significance at all in the timing of these supernovae, that in fact they may have occurred hundreds of years apart, if not thousands, in their galaxy and that we're only coincidentally seeing them this close together in time from our particular point of view. So how could "something odd [be] going on there"?

I don't think anything unusual is going on... I was just suggesting the possibilities. Like I said, there is nothing statistically unreasonable about clustered events like this in a small percentage of the galaxies under observation.

[atalas]

Great work as always Jay! It's also good seeing the comparison of the 2005 and the recent 2011 SN...nice!


Cheers

Louie