MOSCOW, July 12Scientists have explained why all known white dwarfs — Earth-sized objects that remain after the death of a star like our Sun when the fusion reaction of carbon fusion from helium ceases — have less mass than Einstein's theory predicts. Astrophysicists and cosmologists of the IKBFU I. Kant as part of the scientific team came to the conclusion that in order to describe these compact stars, it is necessary to use a modified theory of relativity. The results of their research are published in Symmetry.
The university recalled that the properties of space objects are usually described by the general theory of relativity (GR), put forward by Albert Einstein at the beginning of the 20th century. General relativity describes gravity — the attraction of bodies to each other — as a manifestation of the geometric properties of space and time.
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According to scientists, this theory gives modern physicists the opportunity to explain and predict many phenomena in astronomy and astrophysics, but for explaining some facts, not classical general relativity, but its augmented versions are better suited.
“Physically meaningful solutions can be obtained if we consider an additional term in the GR equations, which is quadratic in curvature (a value that characterizes the degree of space curvature),” explained the head of the laboratory of astrophysics and cosmology, senior researcher at the laboratory for mathematical modeling of complex and nonlinear systems of the Baltic Federal University named after Immanuel Kant (BFU) Artem Astashenok.
According to him, it was the introduction of an additional term into the GR equations that made it possible to explain why all currently known white dwarfs have a smaller mass than classical theory predicts.
«According to GR, their maximum mass should not exceed about 1.5 solar masses, but observations show that the upper mass limit is below the predicted limit, less than 1.4 solar masses,» Astashenok said.
June 5, 03:00
The closest white dwarf to the solar system is a component of the double star Sirius. The neighbor of the white dwarf is another star, the luminosity of which is 25 times higher than the sun. Sirius is about 8 light years away from the solar system, so it can often be observed in the sky.
In the future, researchers plan to apply a simple modified theory of gravity to other cosmic phenomena: nova and supernova explosions, as well as accretion — the flow of gas from one star to another, which occurs in binary systems.
The study involved scientists from the BFU, the Catalan Institute for Scientific Research (ICREA), the High Council for Scientific Research of Spain (CSIC) and the Aristotle University in Thessaloniki, Greece .
IKBFU is a member of the Priority 2030 state support program for Russian universities.