SELF

60

S.B. Karavashkin and O.N. Karavashkina

Having considered these clusters, we can tell that the primary stars, which have formed the primary association on whose basis then the galaxy formed, were arranged also compactly, and during the evolution, this association did not encounter any catastrophic changes.

However, despite NGC 3310 is compact and fast-rotating, its nucleus have not separated, as it often occurs in such cases, though the radius of the orbit of its centre is large. The clearly expressed single spiral and full absence of additional short spirals say us about the integral nucleus. The massive and compact arm of this galaxy tells of the radius of nucleus' orbit. As we revealed before, with the growing radius of the orbit of charge centre, the concentration of equipotential lines of dynamic field has to grow, too, and just this makes the arm so massive.

We would mention, the compact galaxies sometimes are able to take quite interesting shapes; one of such we can see in Fig. 19 [19].

a

b

Fig. 19. The galaxy NGC 4650A: a - positive image, b - negative. "Located about 130 million light-years away, NGC 4650A is one of only 100 known polar-ring galaxies… This is the vertical polar ring which we see almost edge-on in Hubble's Wide Field Planetary Camera 2 image of NGC 4560A, created using 3 different color filters (which transmit blue, green, and near-infrared light)" [19]

As far as the researchers think, "Their unusual disk-ring structure is not yet understood fully. One possibility is that polar rings are the remnants of colossal collisions between two galaxies sometime in the distant past, probably at least 1 billion years ago. During the collision the gas from a smaller galaxy would have been stripped off and captured by a larger galaxy, forming a new ring of dust, gas, and stars, which orbit around the inner galaxy almost at right angles to the larger galaxy's disk" [19]. However so ideal shape of the nucleus gives us a doubt that the collision did not violate its ideality. And should the larger galaxy captured some smaller, we would observe not one disk but two, or rather a common halo of dust with a newly-forming structure, since the less powerful disk of smaller galaxy would be either absorbed by the field of larger galaxy's disk or would have not so ideal shape, when it rotated in the plane perpendicular to the plane of larger galaxy rotation.