This is a fantastic image!!!
Wish I had more time to comment on it.
R Jay Gabany is a master astrophtographer and extremely good at making RGB portrait of galaxies. He is also a master at teasing out faint details in the outer parts of galaxies and in their surroundings.
Today's portrait is a stunning portrait of starbursting dwarf galaxy NGC 4449. The brilliance of its blue clusters and pink emission nebulae is fantastic.
It is obvious from this picture that NGC 4449 is both similar to, and different from, the Large Magellanic Cloud. It is similar to the LMC because both these galaxies are relatively small, yet extremely full of young bright stars and nebulae. Also, both galaxies are a bit "lopsided": the LMC forms most of its new stars in and around the Tarantula Nebula on one side of the galaxy, and today's APOD makes it clear that more stars are forming on the lower left side of NGC 4449 than on its upper right side.
A remarkable difference between the LMC and NGC 4449 is that the LMC has a central bar with little star formation, but NGC 4449 is forming incredible numbers of stars in its central area.
GRI photography by SDSS has also shown that NGC 4449 has a relatively extensive halo of infrared-bright old stars. I don't know if the LMC has anything similar.
Let's return to today's APOD. To me it is almost shocking to see the color difference, as well as the overall difference, between NGC 4449 and the small dwarf that is about to merge with it. While NGC 4449 is flamboyantly blue and pink, the small dwarf is a dull reddish beige color. NGC 4449 is full of O and B-type stars, brilliantly blue in color, and pink emission nebulae. But the small dwarf galaxy has no really young bright stars at all. All its brightest stars are red giants, which may be billions of years old. No nebulae and no dust is visible in the dwarf galaxy. I have to say that I am glad that R Jay Gabany included a blue galaxy in his inset, otherwise I might almost have doubted that he had used the same filters and the same color balance when he photographed NGC 4449 and when he photographed the small dwarf galaxy.
So all in all, this is a fantastic image, wonderfully esthetically pleasing and scientifically completely fascinating!
Ann