Roy, you can't use redshift as a perfect measurement of distance!I'm providing the best current distance estimates along with their errors. I do not know which of the two galaxies is nearer. The measurements do not make it certain, and I see nothing in the images to suggest which is the closest. It is also hard to determine the degree to which the elliptical is perturbed, because that is much less obvious is such structures than it is in spiral galaxies.[youtube][/youtube]I took those distances from the Wikipedia entries. The elliptical is visibly farther, and unperturbed. Are you defending the narrative because an astronomer wrote it? Or because a non-astronomer questions it?
We don't know how far apart they are to that precision. The distance estimates to these objects are determined solely from redshift and then conversion to a Hubble distance. There are measurement uncertainties, the Hubble constant uncertainty, and a relative motion unknown, as well an an uncertain time when the galaxies were at their closest and most of the tidal distortion was occurring.
Current data:
NGC 2936: z = 0.023557 ± 9.29e-6 -> Hubble distance 109.10 ± 7.65 Mpc (356.08 ± 24.97 Mly)
NGC 2937: z = 0.022647 ± 8.84e-6 -> Hubble distance 105.08 ± 7.36 Mpc (342.96 ± 24.02 Mly)
You cannot assess information like this without considering the error bars.
Consider NGC 6050:
According to my software (and based on these two galaxies' redshift), NGC 6050A (at left) is located at a distance of 120 megaparsecs (420 million light-years), but NGC 6050B (at right) is located at a distance of 140 megaparsecs (480 million light-years). If we believe that redshift gives us the perfect distances to these two galaxies, we must assume that NGC 6050A is 60 million light-years closer to us than NGC 6050B (which is about the distance between the Milky Way and the Virgo Cluster).
Take a look at this map of the location of the Virgo Cluster in constellation Virgo:
Can you take a look at the location of the Virgo Cluster in the sky, some ~60 million light-years away from us, and spot the monstrous elliptical galaxy M87 in there? No?
But NGC 6050 A and B are not only cosying up to one another, they are also pretty much the same size. That makes it impossible for them to be 60 million light-years apart. It's impossible!
And as for the interacting galaxies of Arp 142, they are not 17 million light-years apart, either. Believe me, they are not.
Ann
Statistics: Posted by Ann — Tue Jul 30, 2024 7:22 pm — Replies 9 — Views 487