Inseparable galactic twins

Jul 03, 2013
Credit: ESA/Hubble and NASA

(Phys.org) —Looking towards the constellation of Triangulum (The Triangle), in the northern sky, lies the galaxy pair MRK 1034. The two very similar galaxies, named PGC 9074 and PGC 9071, are close enough to one another to be bound together by gravity, although no gravitational disturbance can yet be seen in the image. These objects are probably only just beginning to interact gravitationally.

Both are spiral galaxies, and are presented to our eyes face-on, so we are able to appreciate their distinctive shapes. On the left of the image, PGC 9074 shows a bright bulge and two spiral arms tightly wound around the nucleus, features which have led scientists to classify it as a type Sa galaxy. Close by, PGC 9071—a type Sb galaxy—although very similar and almost the same size as its neighbor, has a fainter bulge and a slightly different structure to its arms: their coils are further apart.

The of both objects clearly show dark patches of dust obscuring the light of the stars lying behind, mixed with bright blue clusters of hot, recently-formed stars. Older, cooler stars can be found in the glowing, compact yellowish bulge towards the center of the galaxy. The whole structure of each galaxy is surrounded by a much fainter round halo of old stars, some residing in .

Gradually, these two neighbors will attract each other, the process of star formation will be increased and tidal forces will throw out long tails of stars and gas. Eventually, after maybe hundreds of millions of years, the structures of the will merge together into a new, larger galaxy.

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Tuxford
1 / 5 (4) Jul 03, 2013
Or...these two galaxies have a common origin, one spawned from the other, and are gradually separating. Likely, they have already separated beyond the maximum distance for the influence of gravity. If the reverse were true, why don't we see more intermediate examples. Not a third galaxy anywhere nearby in this view. Here is a more clear example of the parent-daughter process.

http://phys.org/n...ars.html

Fleetfoot
5 / 5 (2) Jul 04, 2013
Likely, they have already separated beyond the maximum distance for the influence of gravity.


Their separation is measured, that is not true. They are much closer than we are to Andromeda yet we are bound to it and we are falling into the Virgo Cluster which is much farther away than this pair.

If the reverse were true, why don't we see more intermediate examples.


Wrong way round. With galaxies scattered randomly, occassionally two will come close enough to interact. If your nonsense were true, there should be a regular stream of new galaxies coming out of an old one so why don't we see a new galaxy forming in the core of each of these? In fact every pair should produce two new pairs, etc. so how could these two be alone?

It is obvious that these two are regular, symmetric galaxies which must be approaching each other, if they had previously been closer and were separating, there would be tidal tails from both forming a bridge between them.

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