Nebulae that forms bubbles (various APODs, 28 Apr 2006)

[harry]

Hello All

How do Nebula make bubbles?

Is there a special school where they learn to do this?

APOD: 2005 November 7 - NGC 7635: The Bubble Nebula
http://antwrp.gsfc.nasa.gov/apod/ap051107.html

APOD: 2006 April 28 - NGC 7635: Bubble in a Cosmic Sea
http://antwrp.gsfc.nasa.gov/apod/ap060428.html

APOD: 2004 July 16 - The Bubble
http://antwrp.gsfc.nasa.gov/apod/ap040716.html

APOD: 2004 March 28 - Stars and the Bubble Nebula
http://antwrp.gsfc.nasa.gov/apod/ap040328.html

http://www.aao.gov.au/images/captions/int010.html
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APOD: 2006 April 17 - Barnard's Loop around the Horsehead Nebula
http://antwrp.gsfc.nasa.gov/apod/ap060417.html

One possibility is particle winds expelled by massive stars in the bubble's interior that are pushing out the glowing gas. This answer has been recently found to be inconsistent with measured wind velocities, however. Another possibility is that the expanding shells of old supernovas have sculpted the unusual space cavern. An unexpected clue of hot X-ray emitting gas was recently been detected escaping the N44 superbubble

APOD: 2005 April 20 - Barnard's Loop Around Orion
http://antwrp.gsfc.nasa.gov/apod/ap050420.html
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APOD: 2006 February 6 - The N44 Superbubble
http://antwrp.gsfc.nasa.gov/apod/ap060206.html

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APOD: 2006 February 2 - Thor's Helmet in H-Alpha

http://antwrp.gsfc.nasa.gov/apod/ap060202.html

The helmet is actually more like a cosmic bubble, blown as the wind from the bright, massive star near the bubble's center sweeps through the surrounding molecular cloud. Known as a Wolf-Rayet star, the energetic star is a blue giant thought to be in a brief, pre-supernova stage of evolution

APOD: 2005 November 19 - NGC 2359: Thor's Helmet
http://antwrp.gsfc.nasa.gov/apod/ap051119.html

Notice the small bubble in the bubble.

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APOD: 2005 April 15 - RCW 79: Stars in a Bubble
http://antwrp.gsfc.nasa.gov/apod/ap050415.html


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APOD: 2004 August 19 - Windblown N44F
http://antwrp.gsfc.nasa.gov/apod/ap040819.html

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APOD: 2003 October 16 - NGC 6888: X-Rays in the Wind
http://antwrp.gsfc.nasa.gov/apod/ap031016.html
Notic the filaments,,,,,,,,,,,,,,,Orin

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APOD: 2003 April 10 - Energized Nebula in the LMC
http://antwrp.gsfc.nasa.gov/apod/ap030410.html

While emission nebulae generally show the familiar red light from ionized hydrogen atoms - hydrogen atoms with their electrons stripped away - ionized helium atoms are tracers of even higher energy interactions. The intriguing filaments of helium emission make this and other recently studied emission nebulae most exceptional

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APOD: November 17, 1998 - NGC 7635: The Bubble Nebula

http://antwrp.gsfc.nasa.gov/apod/ap981117.html
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APOD: October 2, 1997 - Colliding Supernova Remnants
http://antwrp.gsfc.nasa.gov/apod/ap971002.html
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APOD: September 28, 1997 - A Wolf Rayet Star Bubble

http://antwrp.gsfc.nasa.gov/apod/ap970928.html

APOD: January 3, 1997 - A Wolf-Rayet Star Blows Bubbles
http://antwrp.gsfc.nasa.gov/apod/ap970103.html

APOD: August 26, 1996 - A Wolf-Rayet Star Bubble
http://antwrp.gsfc.nasa.gov/apod/ap960826.html

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So! are they bubbles or just the resultant shape from an Hour Glass.