Astronomy Picture of the Day -- M82: Starburst Galaxy with a Superwind

NASA ^ | October 06, 2011 | (see photo credit)

[SunkenCiv]

Explanation: Also known as the Cigar Galaxy for its elongated visual appearance, M82 is a starburst galaxy with a superwind. In fact, through ensuing supernova explosions and powerful winds from massive stars, the burst of star formation in M82 is driving the prodigous outflow of material. Evidence for the superwind from the galaxy's central regions is clear in this sharp composite image, based on data from small telescopes on planet Earth. The composite highlights emission from filaments of atomic hydrogen gas in reddish hues. The filaments extend for over 10,000 light-years. Some of the gas in the superwind, enriched in heavy elements forged in the massive stars, will eventually escape into intergalactic space. Triggered by a close encounter with nearby large galaxy M81, the furious burst of star formation in M82 should last about 100 million years or so. M82 is 12 million light-years distant, near the northern boundary of Ursa Major.

[SunkenCiv]

[Credit & Copyright: Dietmar Hager, Torsten Grossmann]

[aruanan]

Good thing that's happening way out there.

[SunkenCiv]

Another "Michigan's Highways" ping. ;')

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[spetznaz]

Absolutely beautiful.

[Louis Foxwell]

And deadly to small living creatures. If this occured in our own galaxy what would be the effect of life on earth?

[spetznaz]

I was watching some documentary on various types of extinction level events that can destroy life on Earth (e.g. say a major asteroid strike etc). One of the more interesting ones was a gamma-ray burst from some collapsing star within our galaxy. As it collapses, two bursts come out of opposite ends, and any thing in its path that is an organic lifeform is done (apparently even the most radiation resistant organism on Earth, some bacteria, would not be able to escape the effects). According to the program, one of the largest mass extinctions on Earth (there have been 5 of them ...some interesting reading there) called the Ordovician Extinction that killed the second largest number of lifeforms of the 5 mass extinctions was probably caused by a gamma-ray burst.

The good news? Most people exposed to it would go quickly. It is only those not directly affected who would die slowly.

Which is why I always say that one shouldn't worry too much, because if something bad ever happens it will probably be like the end of the Sopranos ...the screen will simply go black.

[left that other site]

And SOMETIMES...

A cigar is just a cigar.

[gargoyle]

...M82 should last about 100 million years or so...

...Awwww, damn! Guess I'd better save this...

[SunkenCiv]

I’d like to read more about that hypothesis.

The Ordovician extinction was due to massive and worldwide glaciation that came on kinda sudden-like. I don’t find gradualist models for ice ages compelling.

There’s an iridium abundance in the terminal Ordovician stratum, but this is regarded as inconclusive (it sez here). Iridium abundance (as well as chromium) is attested at the K-T boundary, pretty much everywhere it’s been studied since Walter and Luis Alvarez articulated their theory. Iridium is also associated with the Eltanin impact which happened circa 2 million years ago.

A supernova more or less in proximity would generate (among other things) Plutonium 244 (it sez here), which is sufficiently long-lived (half-life is 80 million years) to be possibly diagnostic of a supernova explosion.

[SunkenCiv]

Pretty — from a safe distance. :’)

[spetznaz]

The documentary (actually a series) that I had watched was Mega Disasters (after a quick search - episode 15 from season 2) titled Gamma Ray Burst. That series was a little over the top (65% hyperbole/ 35% hard science), but entertaining nonetheless.

[SunkenCiv]

Oh, I may have that on disk then... around here... somewhere...