Evidence for Supernovas Near Earth

[james_davis_nicoll]

It seems obvious that you wouldn't want a supernova exploding near Earth. Yet there is growing evidence that one did—actually, more than one. About 10 million years ago, a nearby cluster of supernovas went off like popcorn. We know because the explosions blew an enormous bubble in the interstellar medium, and we're inside it.

Comments

[w. dow rieder (from livejournal.com)]

Given the timescale involved, I wonder whether the solar system was actually near the supernova cluster when it went off. My (very rough) estimate of how far the sun would have moved with respect to other stars not part of a kinematic group, is larger than the size of the bubble.

[nelc.livejournal.com]

Would the bubble move with the originating stars' vectors, or would it be dragged along with the interstellar medium? As I recall, Sol follows a fairly non-eccentric orbit in the galaxy, so it would probably track the average rotation of interstellar gas closely, I think.

[kjn]

I'm not an astrophysicist, but my layman's guess would be that the bubble would have three different vectors interacting:

First the vector of the originating stars, then the vector that the novas imparted on the bubble (ie what caused it to expand), and last the interstellar medium interacting with the bubble. I imagine the last one first one would affect the shape of the bubble, before imparting any momentum to it, though.

[(Anonymous)]

The Earth has even encountered the blast wave of a relatively nearby (around 100 light years) supernova around three million years ago. This is known because some of the radioactive iron-60 produced in the supernova was incorporated into ferromanganese crusts found in the deep ocean. With a very sensitive mass spectrometer, this can be measured. More here: http://www.gams.ph.tum.de/index.php?id=36

-- Karsten Kretschmer

[bruce munro (from livejournal.com)]

Well, that's actually fairly reassuring: if the australopithecines made it through a fairly nearby supernova, I'd say our odds of surviving a comparable event are good.

[agharta75.livejournal.com]

And when the Earth leaves the bubble, the intelligence of every living creature increases tenfold (as Poul Anderson predicted).

[sean o'hara (from livejournal.com)]

Considering humanity evolved after the supernova, the logical conclusion is that Anderson got things backwards and we'll become idiots if we leave.

[keithmm.livejournal.com]

So what you're saying is that if they just hang in there, the Libertarian Party has a real shot.

[montedavis.livejournal.com]

:-) ^22

[david wilford (from livejournal.com)]

Here's a nice footnote on the Local Bubble and Local Fluff, from the BBC:

http://www.bbc.co.uk/dna/place-london/plain/A755994#footnote3

[tamar-lindsay.livejournal.com]

"Every year in December, Earth passes through the "helium focusing cone," a region where this neutral helium is concentrated by the gravitational influence of the sun....the strongest source of charge exchange x-rays in the solar system."

So...the X in Xmas really stands for X-rays?

[roseembolism.livejournal.com]

And damn it, if it wasn't for that bubble, we could totally have ramjets now! THANKS OBAMA

[fridgepunk.livejournal.com]

We're oddly enough unique among our immediate stellar neighbours in that Sol is travelling through an especially dense region of gas (apod.nasa.gov/apod/ap000411.html) produced by a string of coreward supernovas (http://apod.nasa.gov/apod/ap000412.html).

Altair is just about to enter the stream we're in while all the other nearest stars don't go near it, meaning that if we launched a ramjet within the brief span of 10,000 years we have until we leave this stream of gas we'd be able to shuttle ramjets back and forth from here to there for a while (if ramjets worked, of course).

(of course in 10,000 years the music would stop and everyone would have to stay where they are or follow the cloud out of the galaxy, but that's only the span of human civilisation to date so...)

[nebogipfel.livejournal.com]

Now this would be an interesting setting for interstellar stuff.
Although the cut-off civilizations still could coummunicate

[(Anonymous)]

Now this would be an interesting setting for interstellar stuff.
Although the cut-off civilizations still could coummunicate