Astronomers examined the structure of a distant white dwarf: the dead star turned out to be much larger than modern theories of the evolution of luminaries allow.
Stellar seismography made it possible to study the internal structure of the white dwarf KIC08626021. It was found that its size does not fit in any way with the predictions of theories of stellar evolution. If the observations are confirmed, astronomers will need to refine existing models of star growth and death. Scientists write about this in an article published in the journal Nature.
Small and medium-sized stars become swollen red giants in the later stages of their lives. This is how the Sun will become in a few billion years: they do not have enough mass to form a neutron star or black hole, and at the end of their evolution, red giants shed their outer shells, turning into white dwarfs. In fact, these are naked superdense nuclei in which thermonuclear reactions have already ended. The white dwarf, KIC08626021, is located 1,375 light years from Earth and has been studied with the Kepler Space Telescope.
Observations of the vibrations of KIC08626021 made it possible to conduct its "seismological" survey and, by the nature of the vibrations, to examine the internal structure of the interior of the white dwarf. It has been shown that its central homogeneous core has a mass of about 0.45 solar masses and is 86 percent oxygen. The work of the Canadian astrophysicist Gilles Fontaine and his colleagues has already been called the "amazing foundation" of the theory of stellar evolution. And this is not surprising: the figures obtained are 40 and 15 percent higher than the existing models of white dwarf formation allow in principle.
“This is a key find that will force us to reconsider our views on the process of dying stars, - said Professor Fontaine in an interview with the press service of the University of Montreal. “But first, more observations will be needed to confirm this on other stars. Perhaps this one is just an anomaly."
Sergey Vasiliev