APOD: Sharpless 308: Star Bubble (2013 Dec 24)

[APOD Robot]

Sharpless 308: Star Bubble

Explanation: Blown by fast winds from a hot, massive star, this cosmic bubble is huge. Cataloged as Sharpless 2-308 it lies some 5,200 light-years away toward the constellation of the Big Dog (Canis Major) and covers slightly more of the sky than a Full Moon. That corresponds to a diameter of 60 light-years at its estimated distance. The massive star that created the bubble, a Wolf-Rayet star, is the bright 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 violet hues.

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[Boomer12k]

Awesome!!! I love bubble nebula....and ring nebula, etc...

I used to fiddle with 3d graphics on my Amiga Computer. One would be a faceted glass ball....then you have some light sources, then you put a "ray" of yellow, through the sphere, and you would get reflections, and it was really neat. And it looks a bit like this photo.

This is just a quick illustration. And this Bubble Nebula reminded me of this....
You can see the reflections off the inside of the glass, and I used to get some interesting reflections, and effects.

It amazing that a star can blow a bubble 60 light years big!!!!!! The Universe is a truly amazing place....
At 20 times the mass of the Sun, should it not also reduce into a Black Hole???


Wishing you all a Happy "Whatever you are into", this week.....

:---[===] *

[firstnagnitude]

Look familiar?

[just curious]

If the bubble is only 70k years old, how is it some 30 light-years in radius?

[Ann]

That's a fine picture of a cosmic Christmas bauble-bubble!

The Wolf-Rayet star in the middle is quite interesting. It is apparently very far away - the Hipparcos parallax is 0.72 ± 0.62 milliarcseconds - and yet, and in spite of being inside a bubble of its own making, it still has a negative (blue) B-V index, -0.056 (Johnson) or -0.066 (Tycho). And its tiny parallax, coupled with its 6.279 V magnitude, might make it as bright in V light as 3,500 solar luminosities. I'm impressed.

Bright Star catalog wrote this about the Wolf-Rayet star:

One of only four WR stars bright enough to have been observed spectroscopically in UV by COPERNICUS. Reminiscent of spectra of nova-like variables during an outburst, which is typical of close binaries. Circumstellar matter. Helium rich. HII ring. Shell surrounding the star is estimated be three solar masses.

The red star nearby, Omicron 1 Canis Majoris, is also very interesting. It has an even tinier (but very uncertain) parallax than the WR star, but it has basically the same proper motion as the Wolf Rayet star. Clearly the two are related and born from the same region of star formation. Omicron 1 Canis Majoris is very red (its Johnson B-V index is 1.740, its Tycho index is 2.103) and it is spectral classification is K3Iab.

I was a bit surprised at one thing that APOD Robot wrote:

Relatively faint emission captured in the expansive image is dominated by the glow of ionized oxygen atoms mapped to violet hues.

Well, I think that you normally map OIII emission as blue, not violet. I googled violet and got this and this. (And this.)

Ann

[Beyond]

Why, Ann... that's just incredible

[neufer]

If the bubble is only 70k years old, how is it some 30 light-years in radius?

Fast (~130 km/s) winds from the Wolf-Rayet star?

http://apod.nasa.gov/apod/ap090423.html

[Ron-Astro Pharmacist]

Why, Ann... that's just incredible

I agree with Beyond.

I think what I see as a "Celestial Dolphin surfacing from a Sea of Stars" might also agree…

Dolphin.jpg (8.12 KiB) Viewed 5047 times

…but I have little chance understanding fish-talk and your knowledge of the beauty of color. It’s great to know some do.

[NickHerlick]

It looks like the star field surrounding Sharpless 308 includes many "rings" of stars. Is that a real phenomenon (not projecting patterns that aren't there)? And if they are real what are the physical events that cause stars to group in ring shapes?

[geckzilla]

It looks like the star field surrounding Sharpless 308 includes many "rings" of stars. Is that a real phenomenon (not projecting patterns that aren't there)? And if they are real what are the physical events that cause stars to group in ring shapes?

Just your brain's natural tendency to see patterns. http://en.wikipedia.org/wiki/Asterism_%28astronomy%29

[neufer]

It looks like the star field surrounding Sharpless 308 includes many "rings" of stars. Is that a real phenomenon (not projecting patterns that aren't there)? And if they are real what are the physical events that cause stars to group in ring shapes?

Just your brain's natural tendency to see patterns. http://en.wikipedia.org/wiki/Asterism_%28astronomy%29

---

<<Here are two patterns, from Steven Pinker’s book, The Better Angels of our Nature. One of the patterns is randomly generated. The other imitates a pattern from nature. Can you tell which is which?

Here is Pinker’s explanation: "The one on the left, with the clumps, strands, voids, and filaments (and perhaps, depending on your obsessions, animals, nudes, or Virgin Marys) is the array that was plotted at random, like stars. The one on the right, which seems to be haphazard, is the array whose positions were nudged apart, like glowworms.">>

[Beyond]

According to the poiple woids, they've both been fooled with, so there is no 'natural' pattern and the question of which is which, is a moot point.

[Prospero]

My first thought was - why is the central star not dead-centre(center) ?
Then, perhaps the gas bubble is running into (slowing down in) more dense interstellar medium one side cf. the other ???

Ann, very interesting, thank you.

I googled violet and got this and this. (And this(**)

Some decades ago, (even in another century!), I was required to read up on man-made dyes and Ann's post rang a bell,
so I gooogled as well,

and from this :- http://en.wikipedia.org/wiki/Mauve
"Mauve is also sometimes described as pale violet."

Mauve, or mauveine was the first man-made (aniline) dye,
70,000 years ago 'windblown !' humans were using woad to similar effect.

PS (**) could'av done without the disturbing last one Ann, looks like a demented grandchild of Sir John Major (one time PM), that's one in-joke for the English amongst us

PPS
Hesitates to ask : who remembers "one-eyed, one-horned, flying, purple people eater" ?

[rstevenson]

Hesitates to ask : who remembers "one-eyed, one-horned, flying, purple people eater" ?

Ackkk!! Now I've got that going through my head instead of Have Yourself a Merry Little Christmas.

Rob

[Prospero]

instead of Have Yourself a Merry Little Christmas.

Arghhh ! Sorry !
Merry Crimble everyone