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In the clouds of Rho Ophiuchi | by write_adam
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In the clouds of Rho Ophiuchi

[description borrowed from apod.nasa.gov/apod/ap070903.html]

The many spectacular colours of the Rho Ophiuchi (oh'-fee-yu-kee) clouds highlight the many processes that occur there. The blue regions shine primarily by reflected light. Blue light from the star Rho Ophiuchi and nearby stars reflects more efficiently off this portion of the nebula than red light. The Earth's daytime sky appears blue for the same reason. The red and yellow regions shine primarily because of emission from the nebula's atomic and molecular gas. Light from nearby blue stars - more energetic than the bright star Antares - knocks electrons away from the gas, which then shines when the electrons recombine with the gas. The dark regions are caused by dust grains - born in young stellar atmospheres - which effectively block light emitted behind them.

 

Details for the astronerds:

 

I've always struggled with LRGB imaging -- the light pollution gradients are painful. And of course from my latitude (44deg), the gorgeous Ophiuchus clouds are very low in the soup of the horizon. But I ventured to darker skies this weekend, used a LP filter for Luminance, and hammered away at the gradients with Gradient Xterminator (a PS plugin that's worth every penny).

 

FSQ-85 & STL-11000M

LRGB (minutes) = 65:50:50:60

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Taken on May 11, 2011