SELF

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O.N. Karavashkina and S.B. Karavashkin

The galaxy M 51, Fig. 2.27, is seen with well better resolution than NGC 6945 shown above. It has quite typical appearance of maximal and minimal potential. Between the array of concentrated weighty matter in the arms in anti-fronts of M 51, we see not void space but haze, it is especially distinctive in the negative image (b) - this is just the concentration of light negatively charged ions on the maximums of positive potential of the field. Shklovsky gives the gas concentrations in the arms and between them: 3 - 5 cm- ³ and 0,2 - 0,3 cm- ³ accordingly, which means dozen times difference [1, p. 50].

a                                                                            b

Fig. 2.27. The substance distribution in maximums and minimums of field potential by the example of galaxy M 51: in the positive image (a) we can see the arrays of massive substance concentrated on minimums of field; in the negative image (b) we see that the between-arms space is not void but filled by haze of lighter substance, http://heritage.stsci.edu/gallery

To have a complete pattern of processes, we have to emphasise, in Fig. 2.22 we showed a plain pattern of field, while in reality the field of young galaxy is spherical and its three-dimensional front is inscribed not in a circle but in a sphere. Though, as we show in Fig. 2.28, the balance of gravity forces affecting the substance (orange radial arrows) and centrifugal forces (red horizontal arrows) makes the substance effectively flowing to the equatorial plane.

Fig. 2.28. Balance between gravity forces affecting the galactic substance (orange radial arrows) and centrifugal forces (red horizontal arrows) makes the substance effectively flowing to the equatorial plane

Each of affecting forces (dynamic electric field and centrifugal forces) from its side tends to concentrate the substance in arms, to make more plain both the arms and system as the whole, - again, to the equatorial plane, although with it the galactic field remains 3D. Consequently, as the rotational moment of galaxy develops, the peripheral substance flows to the equatorial plane quite fast, and this spatial convexity of arms we can see only in young, still elliptical galaxies. Just this we see in Fig. 2.29 in three galaxies at different stages of evolution. When comparing, it is seen better that more massive arms belong to more plane galaxies. In the galaxy M 64, otherwise called NGC 4826 (see Fig. 2.29a) the amount of peripheral substance is boldly convex in space, but the arms are still under formation. The galaxy ESO 510-G13 (Fig. 2.29b) is still elliptical, we can see its young dusty arms rather on the negative image, and we see them already not so much spatial as in M 64; young and not fully formed arms of the galaxy NGC 3040 still retain some spatial convection; massive arms of adult galaxy M 51 (Fig. 2.27) lay in its plane.

a

b

c

Fig. 2.29. In the course of evolution the arms develop in mass and the galaxies become more flat: a - M 64, or NGC 4826, or Black Eye Galaxy, http://heritage.stsci.edu/gallery/bwgallery/index.shtml ; b - elliptical galaxy ESO 510-G13, http://www.jpl.nasa.gov/images ; c - flat galaxy NGC 3040, http://heritage.stsci.edu/gallery . In the left images there are positives, and in the right images - negatives

In Fig. 2.25 - 2.29 the nuclei of galaxies are well seen; we see that the peripheral stars of nuclei are less hot (red and yellow), closer to the centre blue and white colours tell that there are very hot stars. Below, in the item 2.8, we will consider conditions of thermodynamical balance of stars located at the periphery of galaxies, where they are freely spaced, and see, when overheated, they are able to expand their envelopes up to several orders. But here in the nucleus, because of extremely tight location, stars practically have not space to expand their envelopes. So the stars of galactic nucleus, when overheated, must considerably transform their envelopes, occupying the allowed space, and finally "lay out the steam" somewhat like the air in the balloon, being tightly compressed by the balloon, can quietly blow off through some micro-hole. Limited space in the nucleus has natural affection upon the structure of star envelopes. In this sense peripheral stars have more regular structure of envelopes, the environment not so much affects them, and this enables the envelope to form. Just mentioned circumstance that the peripheral substance tends to flow to the equator and is less dense near the poles destine them to be the regions of leakage of overheated substance from the star envelopes of the nucleus.