Sharpless 171 (2009 Oct 18)

[orin stepanek]

http://apod.nasa.gov/apod/ap091018.html

The Star Pillars of Sharpless 171
Credit & Copyright: Nicolas Outters (Observatoire d'Orange)
Explanation: Towering pillars of cold gas and dark dust adorn the center star forming region of Sharpless 171. An open cluster of stars is forming there from the gas in cold molecular clouds. As energetic light emitted by young massive stars boils away the opaque dust, the region fragments and picturesque pillars of the remnant gas and dust form and slowly evaporate. The energetic light also illuminates the surrounding hydrogen gas, causing it to glow as a red emission nebula. Pictured above is the active central region of the Sharpless 171 greater emission nebula. Sharpless 171 incorporates NGC 7822 and the active region Cederblad 214, much of which is imaged above. The area above spans about 20 light years, lies about 3,000 light years away, and can be seen with a telescope toward the northern constellation of the King of Ethiopia (Cepheus).

Beautiful Photo! Stars keep forming. Makes one wonder that all that dust doesn't get used up! 8)

Orin

[orin stepanek]

I was intrigued by all the dust inside the Milky way and wondered where all that dust came from. I got to wondering about dust between galaxies and found some things on google. http://www.universetoday.com/2009/02/26 ... ervations/

Dust grains block blue light more effectively than red light. "We see this when the sun sets: light rays pass through a thicker layer of the atmosphere," said Scranton, "absorbing more and more blue light, causing the sun to appear reddened. We find similar reddening of quasars from intergalactic dust, and this reddening extends up to ten times beyond the apparent edges of the galaxies themselves."

If intergalactic dust causes reddening; could that cause objects to look like they may be red shifted?

Orin

[bystander]

If intergalactic dust causes reddening; could that cause objects to look like they may be red shifted?

I don't think so. Redshift cause the spectral lines to shift to longer wavelengths (lower frequency, lower energy), but they maintain their general appearance. Absorption causes part of the spectrum to be lost or attenuated, but the wavelengths and frequencies of the remaining spectrum remain the same.

Amazing, this was also the subject of APOD: 2008 Oct 18: Sharpless 171.
Is Oct 18 Sharpless 171 Day? (But 2009 is a repeat of 2005 Sept 27.)

[Chris Peterson]

Beautiful Photo! Stars keep forming. Makes one wonder that all that dust doesn't get used up!

It does, and quite quickly. These star forming regions usually only last a few millions or maybe tens of millions of years before the raw materials are consumed.

[orin stepanek]

Beautiful Photo! Stars keep forming. Makes one wonder that all that dust doesn't get used up!

It does, and quite quickly. These star forming regions usually only last a few millions or maybe tens of millions of years before the raw materials are consumed.

Thanks Chris! I was thinking the whole galaxy. So stars don't form throughout all the dust clouds because the galaxy is a few billion years old. I guess that's true as something has to trigger the star formation. I found this. http://www.space.com/scienceastronomy/p ... 50301.html I'm not sure that that's all of it though.

Orin

[Chris Peterson]

Thanks Chris! I was thinking the whole galaxy. So stars don't form throughout all the dust clouds because the galaxy is a few billion years old. I guess that's true as something has to trigger the star formation.

Dust and gas keeps getting recreated in a galaxy, due to supernovas. Then gravity starts pulling this together, it gets dense enough to support even denser shock fronts from other supernovas or very active stars, and then you get star formation, and the process starts over. Any one area only supports star formation for a short while- which is a good thing. It doesn't seem like a region of active star creation would be the best place for life to develop.