An LRGB composition.
This month I imaged two globular clusters and uploaded them together: M12 and M30. The M12 image can be found
here. The processing and cropping of the two images are similar, so we can make some meaningful comparisons. Clearly they have different appearance. The difference in distances perhaps contributed to the different apparent sizes. In addition, M12 appears more spread while M30 appears centrally concentrated. M12 is closer to the Galactic plane and it is behind a dust screen in Ophiuchus. The dust absorption makes M12 redder, while M30 appears bluer. In addition, the denser core of M30 increases the probability of collision and merging of stars, which lead to blue stars (blue straggler). This also contributes to the bluer color of M30.
If you look hard, you can find a green star to the right of M30's core. It's an RR Lyrae variable. It's brighter in the V filter than in B and R, and thus the green color.
Comments