Starship Asterisk*

[quote="deathfleer"]I wonder what the density of the gases are. Are they as dense as the gases in our atmosphere?[/quote]
No, these gases are less dense than the most perfect vacuum that could be created in an earthly laboratory. Here's a good article on emission nebulae that discusses their densities, temperatures, etc.

http://astronomy.swin.edu.au/cosmos/E/emission+nebula

I wonder what the density of the gases are. Are they as dense as the gases in our atmosphere?

[quote="geckzilla"]Meh, I just realized that in my previous post I had managed to paste the wrong URL for "try this image" ... fixed now, but quite a bit too late. Oh well.[/quote]

Ah, yes, that's very clear!

Meh, I just realized that in my previous post I had managed to paste the wrong URL for "try this image" ... fixed now, but quite a bit too late. Oh well.

[quote="Chris Peterson"]
Here's today's APOD in context.

[attachment=0]ic1805comp.jpg[/attachment][/quote]
So we're looking at the Heart nebula's interventricular septum, created by interstellar snowplows.

[quote="Chris Peterson"]Here's today's APOD in context.

[attachment=0]ic1805comp.jpg[/attachment][/quote]

Thanks. Geckzilla is right: the image is too small. I can match the dark nebula, but I can only match two of the stars.

[quote="Cousin Ricky"]No matter how much I stare and twist my head, I cannot reconcile the APOD and Atlas of the Universe images. :? Can someone give pointers as to how the former fits to the latter?[/quote]
Here's today's APOD in context.

[attachment=0]ic1805comp.jpg[/attachment]

If you scroll down the page, you see [url=http://www.atlasoftheuniverse.com/nebulae/ic1805map.gif]this image[/url] which circles IC 1805. That's where Melotte 15 is. It's too small to match it up, though. Try this image: http://apod.nasa.gov/apod/image/0902/IC1805_Daniel.jpg

No matter how much I stare and twist my head, I cannot reconcile the APOD and Atlas of the Universe images. :? Can someone give pointers as to how the former fits to the latter?

The Center of the Heart.

In the wider image, it looks like a similar thing is happening at the lower left of the heart.

:---[===] *

That's a lovely image, and I'm really happy to see this fascinating cluster and nebula in [b][color=#FF0000]R[/color][color=#008000]G[/color][color=#0040FF]B[/color][/b]! :D

Note the "wall" of ridge in the middle of the picture. That ridge has formed because hot OB stars have been born on both sides of it. It is like having two snowplows piling up snow from opposite directions.

Also note how the blue stars generally cluster close to the "wall". Very red stars are spread far more evenly across the picture. Note the number of very red stars at upper right.

This is a remarkable part of the sky. Close to the Heart Nebula and Melotte 15 massive stars are forming, but they have not yet emerged from their deep dark natal cocoons.

Ann

[url=http://apod.nasa.gov/apod/ap131227.html][img]http://apod.nasa.gov/apod/calendar/S_131227.jpg[/img] [size=150]Melotte 15 in the Heart[/size][/url]

[b] Explanation: [/b] [url=http://apod.nasa.gov/apod/ap080715.html]Cosmic clouds[/url] seem to form [url=http://apod.nasa.gov/apod/ap100716.html]fantastic shapes[/url] in the central regions of emission nebula IC 1805. Of course, the clouds are sculpted by stellar winds and radiation from massive hot stars in the nebula's [url=http://chandra.harvard.edu/edu/formal/stellar_ev/story/index9.html]newborn[/url] star cluster, [url=http://deepskypedia.com/wiki/The_Melotte_Catalogue_of_Star_Clusters]Melotte[/url] 15. About 1.5 million years young, the cluster stars are near the center of this colorful [url=http://jwalk.smugmug.com/Photography]skyscape[/url], along with dark [url=http://hubblesite.org/newscenter/newsdesk/archive/releases/2006/13/]dust clouds[/url] in silhouette. Dominated by emission from [url=http://apod.nasa.gov/apod/ap071102.html]atomic hydrogen[/url], the telescopic view spans about 30 light-years. But [url=http://apod.nasa.gov/apod/ap090214.html]wider field[/url] images reveal that IC 1805's simpler, overall outline suggests its popular name - [url=http://www.atlasoftheuniverse.com/nebulae/ic1805.html]The Heart Nebula[/url]. IC 1805 is located along the northern Milky Way, about 7,500 light years distant toward the constellation [url=http://www.astropix.com/HTML/SHOWCASE/NMW.HTM]Cassiopeia[/url].

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