Stephan's Quintet

[Datalord]

I've been waiting for this beauty to get up and with the latest moonless nights I managed to get some proper imaging time in.

It's 5 galaxies visually close to each other, but NGC7320 is "only" about 40MLY away, while the four main galaxies, who are most likely in the middle of merging, are about 300MLY away.

 

Edited August 2, 2020 by Datalord
Did a bit more processing on the image and updated it in place.

[rl]

Very nice shot. I've always wanted to take this picture myself. NGC7320 (foreground galaxy) is definately a bit bluer than the members at 300M light-year. I wonder if that is down to the extra red shift?

[Datalord]

24 minutes ago, rl said:

I wonder if that is down to the extra red shift?

I didn't think about that, but it does make some sense. 30 to 300 million, however, is not that much redshift. NGC7320 is redshifted at 800km/s, while the others are about 6500km/s. In the grand scheme of things that is not much when compared with the billions of years we otherwise see quasars at.

[rl]

Using your figures, a back-of-envelope calculation suggests light at 500 nm would be shifted by 1.5 nm for the "local" galaxy and 10 nm for the others...not sure whether that would be visible or not. Probably a younger stellar population. 

[MarkAR]

Lovely capture. Such interesting malformations in the spirals.

[DaveS]

That's a very nice capture, one that's on my "to do" list.

I think the ring galaxy to the lower left, PGC69279 is now thought to be an outlier of the other 4, bringing it back up to 5.

[Datalord]

25 minutes ago, DaveS said:

That's a very nice capture, one that's on my "to do" list.

I think the ring galaxy to the lower left, PGC69279 is now thought to be an outlier of the other 4, bringing it back up to 5.

Thanks!

Yeah, I think I read that somewhere as well. But at 300MLY, the distance between that one and the other four must be 10s of MLY. My trigonometry skills are not what they used to be.

[alan potts]

Lovely image and again living up to your name with 14 hours,

Alan