by Ann » Mon Sep 26, 2016 11:25 pm
http://www.spacetelescope.org/images/potw1639a/ wrote:
This picture was taken using the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys, known as ACS for short. It shows NGC 24 in detail, highlighting the blue bursts (young stars), dark lanes (cosmic dust), and red bubbles (hydrogen gas) of material peppered throughout the galaxy’s spiral arms.
Can't spot the red bubbles. And the blue bursts are quite inconspicuous-looking, in view of NGC 24's blue colors: U-B is -0.070, B-V is 0.580. That makes the overall color of NGC 24 bluer than the Sun.
But there is a reason for the lack of red bubbles and the faintness of the blue bursts, and that is the filters used for this image: the filters are centered at 606 nm (orange) and 814 nm (infrared).
It's not easy to highlight blue stars (at, say, 450 nm) and red Ha emission (at 656 nm) with filters like those.
Ann
[quote]http://www.spacetelescope.org/images/potw1639a/ wrote:
This picture was taken using the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys, known as ACS for short. It shows NGC 24 in detail, highlighting the blue bursts (young stars), dark lanes (cosmic dust), and red bubbles (hydrogen gas) of material peppered throughout the galaxy’s spiral arms.[/quote]
Can't spot the red bubbles. And the blue bursts are quite inconspicuous-looking, in view of NGC 24's blue colors: U-B is -0.070, B-V is 0.580. That makes the overall color of NGC 24 bluer than the Sun.
But there is a reason for the lack of red bubbles and the faintness of the blue bursts, and that is the filters used for this image: the filters are centered at 606 nm (orange) and 814 nm (infrared).
It's not easy to highlight blue stars (at, say, 450 nm) and red Ha emission (at 656 nm) with filters like those.
Ann