Some stars hide an anti-aging secret

These stars may have a second life. White dwarfs, the most common meteors in the universe, are able to slow down their aging process.

The most common stars in the universe are able to slow down their aging process. These are the white dwarfs that are able to rejuvenate and have a real second life. The discovery was made by an international research team coordinated by the Italian Francesco Ferraro, University of Bologna and associated with the National Institute of Astrophysics (Inaf), and was published in the journal Nature Astronomy. The result of the study completely changes the knowledge so far believed to be valid on the life cycle of small stars.

The anti-aging secret of stars

Small and medium stars, such as our Sun, become white dwarfs in the last phase of the development cycle and are believed to represent the vast majority of all celestial bodies, up to 98%. According to what has been believed so far, this type of meteors, when they exhaust their fuel, "swell" to eject the outer layers, while the center remains a bare core, very hot, in which nuclear reactions no longer occur. From this moment they gradually go to cool down until they extinguish completely.

Analyzing the images taken by the Hubble Space Telescope of two distinct star clusters, Messier 3 and Messier 13, considered virtually identical to each other, the researchers have discovered for the first time small anomalies that however demonstrate that not all white dwarfs age in the same way. "Our discovery - told Ansa Ferraro - shows that some white dwarfs are able to retain a very thin layer of hydrogen, on the order of one ten-thousandth of the mass of the Sun but enough to allow a minimum thermonuclear activity that allows you to still produce some energy, thus slowing down the process of extinction and cooling, in practice slowing down their aging."

The secret of this "elixir of youth" would be written in their past. The different aging would in fact be driven by a process of stirring of the gas of the star that occurs in the transition leading to the birth of the white dwarf. In stars with an initial mass smaller than average hydrogen can partly conserve itself and thus allow a rejuvenation. The discovery would change the mechanisms used so far to estimate the age of white dwarfs as a function of the brightness alone with a difference, compared to previous calculations, even of 1 billion years.

The study of meteors continues to reveal surprising information about these stars, for example, a research by scientists in the United Kingdom has managed to identify the origin of the first stars, while the Kepler telescope has captured the moment just before the explosion of a supernova.

Stefania Bernardini