V.4 No 1

71

On orbital stability of oscillators

To make this survey more complete, we would like to show one more interesting image of a compact galaxy proving the versatile shapes of spiral arms of such kind of galaxies. In Fig. 30 we can see the positive and negative images of the Hoag's compact galaxy.

a

b

Fig. 30. Hoag's galaxy: a - positive image, b - negative. The image has been copied at http://www.universe.boom.ru/file/new/new3_02.html

"The entire galaxy extends for 120 000 light years. A blue ring of young massive stars contrasts with the yellow nucleus consisting mainly of older stars. The seemed 'interval' separating two stellar families can factually consist some stellar clusters which are too weak to be visible. This object is a background ring galaxy. Ring galaxies can be formed in several different ways. One of possible scenarios is through the collision with another galaxy. Sometimes the second galaxy, fast going through this first, retains the 'splash' of star formation. But in the Hoag's object we can trace no second galaxy which would evidence that the blue ring of stars might remain from the galaxy which passed nearby. Though some astronomers suppose that the collision took place about from 2 to 3 billion years ago. This unusual galaxy was found in 1950 by the astronomer Arthur Hoag. He first suggested that the object similar to a ring of smoke is a planetary nebula remained from a star like the Sun. But he soon changed his opinion, supposing this mysterious object being most probably a galaxy. Observations of 1970 corroborated this supposition, though many details of Hoag galaxy remained a secret. This galaxy lays in the Ophiuchus constellation 600 million light years away from us. The Hubble's Wide Field Planetary Camera 2 yielded this image on 9 July 2001" [26].

As we see, the existing interpretations of conditions at which the galaxies of such kind form suggest to the scientists more questions than answers. While this galaxy is really one of unique objects in the universe. This is a compact, exceptionally balanced galaxy. As the authors of this image say, there in the blue ring are only the second-generation stars formed due to the concentration of intergalactic dust in the arm of this galaxy.

We can judge that this galaxy is well-balanced, because we do not see an arm. Or rather, at the stage of galaxy formation there was an arm which, due to gradual coming to the internal balance in the nucleus, has separated from the nucleus and formed a ring along the equipotential lines of Coulomb field on which, as we revealed in the beginning of this item, the spiral dynamic field is superimposed. With it the galaxy has retained its rotation, as we can see it by the inclined thickenings in the negative image in Fig. 30b.