Compact beskorsaya tight pair of white dwarfs with constantly shrinking distance between them due to gravitational waves can warm up so seriously that they degenerate surface hydrogen layer begins thermonuclear reaction, forming a "new tidal star", say scientists at Cornell University (USA).

Most often, a new star is a white dwarf, "obvorovyvayuschih" neighboring red giant or a normal star and the accumulation of a certain number of hydrogen to trigger the thermonuclear synthesis directly on its surface. (Illustration Courtesy Of Wikimedia Commons.)

Astrophysics under the leadership of Jim fuller (Jim Fuller) believe that almost any pair of white dwarfs with the period of reciprocal treatment from 5 to 20 minutes will cause such a star, and even after 100 000-1 000 000 years after the outbreak of a new two white dwarf, will merge into a single celestial body.

Usually new are the product of the interaction of a system of two stars, where one white dwarf, "a fusion of the burnt out remains of" normal stars (like our Sun), and the other is still a "traditional" main sequence star (or a red giant). If such a pair close to each other, hydrogen from a normal star flows to the surface more dense white dwarf. And when the concentration reaches certain level, can begin thermonuclear reaction, accompanied by an increase luminosity in 1 000 (or even 1 000 000) times. Such stars easily seen from the Earth; they register with 532 years B.C. in China and from 1609-century - in the Western world.

However, not always and not all of these outbreaks repeated the same scenario. Thus, in 2010 the American astronomers were lucky enough to discover that one of them radiates in the gamma range - something hardly be kept in modern theoretical model.

That is why researchers from Cornell University took up modeling a situation in which the population of the star system is represented by a pair of white dwarf white dwarf, without the usual stars. Is what happened. Because of the high gravitational interaction in close systems outer layer of white dwarfs is heated by tidal interaction is much stronger inner layers, and the tidal forces there are very large: from huge density of such a dwarf they 10 000-100 000 000 times higher than the density of most heavy metals. Naturally, tidal waves in such an environment, have more energy and lead to the strongest growth temperature exactly boundary layer. It also contains a small amount of hydrogen (0.01% of the total mass of "burnt out" stars). However, under the action of tidal waves and this is enough for spontaneous generation of thermonuclear reactions in a few points. After the explosions on the surface of the star thermonuclear reaction unstable, because depends on external factors, and not from the tremendous pressure, as in the core of the star is heated and abruptly condense hydrogen beside him, he explodes, causing a series of powerful thermonuclear explosions (that's why we see new).

The model looks quite convincingly that probably means the opening of yet another form new stars. But to test this, will have to wait: according to calculations Jim fuller, such an event - the appearance of new systems of double white dwarfs is happening in our Galaxy once every few decades. However, to facilitate their detection can something that, according to the calculations, before the explosions (and the sharp rise luminosity) of the region "tidal new" is not to be x-ray radiation, usually caused by the accretion of matter less dense stars on the surface of the white dwarf. Because in pairs without a normal star accretion does not happen, there will be x-ray radiation; but in the short-term (a few days) increase the luminosity radiation from such new can be quite different from the standard picture, stress the authors.

A study soon to be published in Astrophysical Journal Letters, and with its Preprint available here.

Based on the materials of Cornell University.