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S.B. Karavashkin and O.N. Karavashkina

As opposite to NGC 3310, the galaxy NGC 3370 shown in Fig. 23 distinguishes i12ptn its properties, though both galaxies have similar age.

a

b

Fig. 23. The galaxy NGC 3370: a - positive image, b - negative. The image has been copied at http://heritage.stsci.edu/2003/24/index.html

The authors of this image tell: "In November 1994, the light of a supernova in nearby NGC 3370 reached Earth. This stellar outburst briefly outshone all of the tens of billions of other stars in its galaxy" [21]. But the supernovae did not essentially change the structure of NGC 3370 and could not do so during so small interval of time. So we can surely state, this galaxy has the same shape as before the explosion of 1994.

The main distinctive feature of this galaxy is that it is non-compact. In Fig. 23 we see that though the nucleus has formed, the periphery consists of dense dust clouds in which the arms are tracked quite vaguely. This vagueness is caused also by the triple nucleus - this is well seen in Fig. 23b. We see in this image that from the dark region of nucleus against the clock pointer go three massive spirals about two periods in length.

This all evidences that the galaxy NGC 3370 has formed not of a compact star cluster but by way of structurisation of some non-compact stellar cluster, which has formed in the dense inhomogeneous dust nebula. At these conditions of formation, the process of structurisation is accompanied by a great redistribution of mass, and this naturally has effect on the shape of galaxy. We can trace this regularity with other non-compact galaxies.