APOD: Stephan's Quintet from Hubble (2019 Jun 03)

[Chris Peterson]

why don't these three system all come together and become one?

They aren't stationary with respect to each other, but in complex multiple body orbits around each other. Over billions of years, they trade angular momentum with each other through tidal interactions, and collisions occur, with yet more exchanges of energy and of mass. Presumably, in tens of billions of years, most of their combined mass will end up in a big blob- a huge elliptical or irregular galaxy, while some part will be ejected permanently into intergalactic space.

[Ann]

Naaah. I was just given that nick by the moderators, because 4725 Angstroms is blue wavelength, and I love blue things.

Love it!

Deep rich blue is a beautiful color.

Speaking of which, I once worked on the same worksite as David Malin. Probably have walked passed him, possibly even talked to him. I am pretty sure he was working with the Anglo Australian Telescope back in the 1980's.

Å, Cheers from Downunder.

He was!

His book, A View of the Universe, was my first enormously useful and fascinating "cosmic color tutorial". I even wrote to him a few times and received some gracious answers from him.

Cheers to you too, C!

Ann

[C Downunder]

Ann

Awesome.

C