Starship Asterisk*

Hubble s Lagoon

Explanation: Like brush strokes on a canvas, ridges of color seem to flow across this scene. But here, the canvas is nearly 3 light-years wide and the colors map emission from ionized gas in the Lagoon Nebula, recorded by the Hubble Space Telescope's Advanced Camera for Surveys. Also known as M8, the nebula is a star forming region about 5,000 light-years distant in the constellation Sagittarius. Hubble's remarkably sharp, close-up view reveals undulating shapes sculpted by the energetic light and winds from the region's new born stars. Of course, the Lagoon nebula is a popular target for earthbound skygazers, too. It features a prominent dust lane and bright hourglass shape in small telescopes with wider fields of view.

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This is lovely! Lovely write-up, too.

Beautiful. Are the blue stars closer than the swirling nebula, or are they shining through it?

Steve Randall wrote:Beautiful. Are the blue stars closer than the swirling nebula, or are they shining through it?

They should be seen if front of it. Likely the nebula is thick enough to be mostly opaque in many places, and the stars that are seen through rather thick dust should be highly reddened.

I found a picture of the Lagoon Nabula that I like. I will only post a link to it, so as not to slow down the loading of this particular thread:

http://www.fromearthtotheuniverse.org/G ... nebula.jpg

Here you can see that the nebula is dominated by reddish-pink light due to hydrogen alpha emission. Most emission nebulae are very pink to red in color due to hydrogen emission.

In the brightest part of the nebula, near the so called Hourglass nebula (which can't be seen here because it is overexposed), the color of the nebula becomes white to yellow-white. The yellowish color is caused by a combination of red hydrogen alpha emission and blue-green emission from ionized oxygen.

You can see that many of the stars in the picture are blue, but not all. The blue stars here are all massive blue stars that are mostly in front of the nebula, though there may be a bit of gas and dust in front of them, too.

Ann

Waves breaking in the stellar lagoon
http://asterisk.apod.com/vie ... 29&t=21226

Second "ripple" from the right looks like a BOB HOPE caricature in profile.
First ripple looks like the top of an alligator's head.
The whole thing reminds me of the Fox Fur Nebula.
Awesome Pic.

Ann wrote:

Steve Randall wrote:Beautiful. Are the blue stars closer than the swirling nebula, or are they shining through it?

They should be seen if front of it. Likely the nebula is thick enough to be mostly opaque in many places, and the stars that are seen through rather thick dust should be highly reddened.

I found a picture of the Lagoon Nabula that I like. I will only post a link to it, so as not to slow down the loading of this particular thread:

http://www.fromearthtotheuniverse.org/G ... nebula.jpg

Here you can see that the nebula is dominated by reddish-pink light due to hydrogen alpha emission. Most emission nebulae are very pink to red in color due to hydrogen emission.

In the brightest part of the nebula, near the so called Hourglass nebula (which can't be seen here because it is overexposed), the color of the nebula becomes white to yellow-white. The yellowish color is caused by a combination of red hydrogen alpha emission and blue-green emission from ionized oxygen.

You can see that many of the stars in the picture are blue, but not all. The blue stars here are all massive blue stars that are mostly in front of the nebula, though there may be a bit of gas and dust in front of them, too.

Ann

Thanks. With those stars in the foreground, the nebula must be awesomely huge!

I enjoyead the zoom link.http://www.spacetelescope.org/videos/heic1015a/

Ann wrote:
I found a picture of the Lagoon Nebula that I like:
http://www.fromearthtotheuniverse.org/G ... nebula.jpg

Here you can see that the nebula is dominated by reddish-pink light due to hydrogen alpha emission. Most emission nebulae are very pink to red in color due to hydrogen emission. In the brightest part of the nebula, near the so called Hourglass nebula (which can't be seen here because it is overexposed), the color of the nebula becomes white to yellow-white. The yellowish color is caused by a combination of red hydrogen alpha emission and blue-green emission from ionized oxygen. You can see that many of the stars in the picture are blue, but not all. The blue stars here are all massive blue stars that are mostly in front of the nebula, though there may be a bit of gas and dust in front of them, too.

Thanks for the laugh, Art!

Ann

the most striking details about many nebula photographs are the structure shapes that strongly resemble media mixture -- smoke tendrils in air, dye diffusing in water, or bok globules that seem to be the innards of a lava lamp.

these complex shapes often have sharply defined boundaries, strong visual (light transmitting/absorbing) contrasts with the surround, coherent dynamic form, and edge turbulence that suggests the interface between two different densities. today's photo, for example, looks almost exactly like the turbulence you would see if you dissolved sculptor's clay in a tank of water, let the clay settle to the bottom of the tank, then shook or stirred the tank to throw the sediment back into solution.

the paradox is: these can't be gravitational structures, because the structure is not averaged or "blurred" by the effects one would expect from stellar radiation acting on gas in a vacuum, diffusive heat within the gas cloud, and the large scale clumping of a single gravitational field. but then what is the surrounding medium that provides the shaping effect? william keel explained to me that this is an active area of current astronomical research. i hope apod can provide some good visual examples and explain how these complex and highly organized structures arise.

What is the estimated distance between grains of dust or individual gas molecules in a cloud like this?

Absolutely magnificent view - could be an immense sand storm in a vast desert.

Can photons actually push dust around? What is energetic light? Or is the "wind" made up of something else?

How can the dust coalesce into new stars or planets when this "wind" is pushing it outward?

biddie67 wrote:Absolutely magnificent view - could be an immense sand storm in a vast desert.

Can photons actually push dust around? What is energetic light? Or is the "wind" made up of something else?

How can the dust coalesce into new stars or planets when this "wind" is pushing it outward?

Energetic light is photons of ultraviolet light. Even more energetic light is photons of X-ray radiation and rare photons of super-energetic gamma rays. Extremely few gamma ray photons are expected to be generated in the Lagoon Nebula. X-rays may be generated by high-mass binaries, when their stellar winds collide. Stellar winds contain a lot of energetic particles, electrons and protons. Energetic photons can indeed push dust around, and of course high-speed electrons and protons can push dust around, too.

Dust that is being pushed outward isn't going to coalesce into new stars and planets. You need dark, cold dust cores for that. See APOD, September 30, 2010.

http://antwrp.gsfc.nasa.gov/apod/ap100930.html

Ann

Say, maybe Ann would like a baboon for a pet since her cat was run over by the Mars rover... Baboons are more brightly colored.

Don't joke about dead cats, Ed!!!

Ann

tim wrote:What is the estimated distance between grains of dust or individual gas molecules in a cloud like this?

If it was all gas then about a millimeter.

If it was all micron sized grains of dust then about ten meters.

Ann wrote:
Don't joke about dead cats, Ed!!!

I'm afraid it's true, Ann:

http://asterisk.apod.com/vie ... 86#p132986

Hmmm... I'm wondering about the identity of that cat's owner. Would Ann have a black-and-white cat?! I think not! That poor pussy cat surely belonged to someone else!

Ann wrote:Don't joke about dead cats, Ed!!!

Ann

Sorry Ann, Guess I’m a little too use to cats… my wife is the Adoption Supervisor at our county Animal Shelter… ergo we have lots of cats… which I love ‘em all… and they have to take a joke now and then. I give them funny names… my wife puts up with me.

Am I seeing something here that is my terrestrial vision putting images into my head?

http://i1013.photobucket.com/albums/af2 ... hst_c0.jpg

Btw just registered today...

Welcome aboard the Starship Asterisk*, greyhawk, but you will need
to confirm your account and login, otherwise you are just a guest.

Ah I thought I was logged in. I am now anyway.

Yay! Congrats and welcome! I'm always glad to see another raptor on the board!

Stuck in the Lagoon’s quagmire
Bad Astronomy | 16 Oct 2010