Shapeless 308 (APOD 2009 April 23)

[neufer]

Explanation: Blown by fast winds from a hot, massive star, this cosmic bubble is huge. Cataloged as Sharpless 308 it lies some 5,200 light-years away in the constellation Canis Major and covers over 2/3 degree on the sky (compared with 1/2 degree for the Full Moon). That corresponds to a diameter of 60 light-years at its estimated distance. The massive star itself, a Wolf-Rayet star, is the bright blue one near the center of the nebula. Wolf-Rayet stars have over 20 times the mass of the Sun and are thought to be in a brief, pre-supernova phase of massive star evolution. Fast winds from this Wolf-Rayet star create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of evolution. The windblown nebula has an age of about 70,000 years. Relatively faint emission captured in the expansive image is dominated by the glow of ionized oxygen atoms mapped to bluish hues.

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Truly astronomical numbers:

<<The amoeba was first discovered by August Johann Rösel von Rosenhof in 1757. Early naturalists referred to Amoeba as the Proteus animalcule after the Greek god Proteus who could change his shape. The name "amibe" was given to it by Bory de Saint-Vincent, from the Greek amoibè (αμοιβή), meaning change. The amoeba is remarkable for its very large genome. The species Amoeba protea has 290 billion base pairs in its genome, and there are 670 billion base pairs in the genome of Amoeba dubia. The human genome is small by contrast, with its count of 2.9 billion base pairs.>>

[rstevenson]

This being roughly 80 LY wide, if it had happened anywhere near us, the nebula would have swept past us (or would be on its way to us). Would such an event have had any effect on life on Earth? Or is it just too tenuous, equivalent to, say, the effect of Fox News on life on Earth?

Rob

[neufer]

This being roughly 80 LY wide, if it had happened anywhere near us, the nebula would have swept past us (or would be on its way to us). Would such an event have had any effect on life on Earth? Or is it just too tenuous, equivalent to, say, the effect of Fox News on life on Earth?

Clarify what you mean by anywhere near us.

Amoeba dubious:

[rstevenson]

In context that should be clear -- anywhere <40 LYs. (Sorry I don't have a weird picture to post along with my reply.)

Rob

[Chris Peterson]

This being roughly 80 LY wide, if it had happened anywhere near us, the nebula would have swept past us (or would be on its way to us). Would such an event have had any effect on life on Earth? Or is it just too tenuous, equivalent to, say, the effect of Fox News on life on Earth?

It would have no effect- nebulas are very tenuous. If you bottled up a bit of it in a lab, you'd call it a hard vacuum. If you were inside the nebula, I'm pretty sure it wouldn't even be visible in the sky. We could only hope Fox News was so invisible as well!

[rstevenson]

Thanks Chris,

One of the things it's so hard to wrap my mind around is how violent much of what we see throughout the universe appears (and, I suppose, how violent much of it is, at least when it's beginning to happen) while at the same time it remains wispy and tenuous compared to solid things like planets.

Rob

[Chris Peterson]

One of the things it's so hard to wrap my mind around is how violent much of what we see throughout the universe appears (and, I suppose, how violent much of it is, at least when it's beginning to happen) while at the same time it remains wispy and tenuous compared to solid things like planets.

The relationship between energy and energy density can be fairly non-intuitive at times. The atmospheric temperature up at the height of the ISS (yes, there is atmosphere up there) is well over 1000°C. But you'd freeze if you were in the shade of the ISS, simply because there aren't enough atoms and molecules to transfer much of that energy to you. Same thing with these nebulas. The gases are heated to thousands of degrees, enough to ionize. But they are so thin that they qualify as a vacuum. Consider comets; we see these apparently dense, bright comas, but they are also pretty good vacuums. We only see them because they're a million miles thick. Nebulas are light years thick. On Earth, you only need to look through a few hundred miles of air until it become pretty opaque. Yet you can see stars through nebulas- just think how thin something has to be to let starlight through a few light years!

[rstevenson]

Excellent explanation Chris. Thank you.

Rob

[BMAONE23]

Another possible example would be the common sparkler (fireworks), The sparks burn at (i believe) 3000 deg or so but they dont hurt your hand as they bounce off it because of their density. If you were to hold a gram of the burning substance in your hand you would recieve a wicked burn but just a few molecules burning in your hand at any given point and you feel nothing of the 3000 deg heat.

[aristarchusinexile]

Another possible example would be the common sparkler (fireworks), The sparks burn at (i believe) 3000 deg or so but they dont hurt your hand as they bounce off it because of their density. If you were to hold a gram of the burning substance in your hand you would recieve a wicked burn but just a few molecules burning in your hand at any given point and you feel nothing of the 300 deg heat.

Yup .. this is good, mind edifying stuff. And that beautiful photo of nice, clean oxygen molecules .. I knew there had to be fresh air SOMEPLACE in the universe.

[vpetriew]

This morning while I was looking at yesterday's APOD of Sharpless 308, a canine popped out of the picture! I think it looks like a border collie or a cockerspaniel with large floppy ears. Everyone in my office had not problem seeing it and thought it was pretty cool.

I've attached a rough outline of this to give you an idea where to look in the picture. My scratches look more like a bird but use the outline to look again at the original image:
http://antwrp.gsfc.nasa.gov/apod/ap090423.html

Is there a nebula called the "Canine Nebula" or the "Puppy Nebula"? If not, I think this would make a great name for this nebula based on Dan Goldman's image! Can you see it?

Vance

Sh308_goldman_Canine_small.jpg (63.02 KiB) Viewed 2564 times

[aristarchusinexile]

Looks more like a Dolphinbird to me, V.

[BMAONE23]

The highlights remind me of a Dolphin rather than a Canine, of course I could just be saying that on Porpose

[aristarchusinexile]

The highlights remind me of a Dolphin rather than a Canine, of course I could just be saying that on Porpose

Riding the wave with BMA.

[vpetriew]

Sorry, but my artistic capabilities painting with a mouse are very rudimentary. The "porpoise" of the drawing is to take a look at the portrait of a canine in the original image )

Vance

[aristarchusinexile]

Sorry, but my artistic capabilities painting with a mouse are very rudimentary. The "porpoise" of the drawing is to take a look at the portrait of a canine in the original image )

Vance

Well Vance, your artwork at least didn't resemble a cat, so perhaps your mouse had a non-local effect.

[vpetriew]

LOL! Good one!