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by japhyr 366 days ago
That is interesting!

They look like they're roughly in the same plane. Is it safe to assume they're roughly in the same plane, or could they be really distant along the line of sight? The similarity in size makes me think they are, but I don't have any reason to be confident in that judgment.
2 comments
perihelions 366 days ago
Those are NGC 4411 a+b and they're indeed right next to each other,

https://noirlab.edu/public/images/iotw2421b/ ("thought to be right next to each other — both at a distance of about 50 million light-years")

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jcims 366 days ago
What's going on directly above with what looks to be 3-4 galaxies interacting?
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o11c 365 days ago
It says that NGC 4410 is (gravitationally) interacting galaxies. After clicking through the link, it calls it RSCG 55 instead and explains more. I don't understand the naming scheme.
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SiempreViernes 365 days ago
The naming scheme is based on the principle "tens of thousand of people have done this over thousands of years, and they all named things themselves". Its not uncommon for objects to have ~20 separate names[1], with some having over a hundred [2].

In this particular case, RSCG 55 means a group of galaxies[3], of which NGC 4410 is one member. Apparently RSCG is the "Redshift Survey Compact Groups" (https://cds.unistra.fr/cgi-bin/Dic-Simbad?RSCG) so 55 is just an index number.

That's also the case for the 4410 after NGC; in that case stands for "New General Catalog". In contrast the Sloan Digital Sky Survey gave NGC 4410 the name SDSS J122628.29+090111.4 where the numbers indicates its position in the sky.

The "index number" and the "position of the sky" are the two most popular naming strategies.

[1] NGC 4410 has 37, but the NGC objects are among the more popular https://simbad.u-strasbg.fr/simbad/sim-id?Ident=+NGC+4410&Nb... [2] https://simbad.u-strasbg.fr/simbad/sim-id?Ident=M87&submit=s... [3] https://simbad.u-strasbg.fr/simbad/sim-id?Ident=RSCG+55&NbId...

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prawn 365 days ago
"like NGC 4410, above them in this image. The four interacting galaxies of that system are connected by tidal bridges, created by the gravity of each galaxy pulling on the others in the system."
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jcims 365 days ago
Dang. I think I got terminology blinded by the time I got there.
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RALaBarge 365 days ago
I believe there would be a difference in their red/blue signatures if they were moving relative to each other, but as you say they clearly are on the same plane
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