Astronomers are getting ready to give a new definition of «star»

© Roberto Molar Candanosa and Sergio Dieterich, courtesy of the Carnegie Institution for Casetek the artist has imagined a pair of heavy brown dwarfs in the constellation of the IndianAstronomers are getting ready to give a new definition of «star»© Roberto Molar Candanosa and Sergio Dieterich, courtesy of the Carnegie Institution for Casepapers to daily updates RIA Science

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The opening of two unusually large brown dwarfs, «failed» stars, and forced astronomers from the United States to think about the fact that the concept of «star» needs a new definition. Their findings were presented in the Astrophysical Journal.

«Our observations show that the concept of «brown dwarf» and «star» need to be revised. It turns out that the most difficult a failed star and the small stars do not differ by weight. Despite this, they develop in completely different ways- the first is fast fading, and the second Shine for billions of years,» said Serge Dietrich (Dietrich Serge) from the Carnegie institution for science in Washington (USA).

Was there a star?

All the stars of the milky Way and other galaxies are born inside a particularly dense clouds of gas, some of which at a certain point in time thickens and begins to harden. With time, temperature and pressure inside these growing clumps rise to such high values that their center start to occur fusion reaction between individual hydrogen atoms.

Such a reaction, according to the calculations of astrophysicists, can occur only within a fairly large object, whose mass is approximately 7% from solar, which is 73 times the mass of Jupiter. Smaller celestial bodies become brown dwarfs — «failed stars» glow weakly in the infrared range and gradually fading.

In recent years, scientists have discovered several new brown dwarfs, the presence of the weather on them, metal «clouds» and a number of other properties that have led many astronomers to believe that they are actually very large planets, not stars. Similar discoveries have revived the debate about where the boundary lies between stars, brown dwarfs and planets.

Dietrich and his colleagues discovered from two objects that do not fit the generally accepted definition of stars and brown dwarfs by studying a couple next to us, large brown dwarfs orbiting the star Epsilon (GJ 845) in the constellation of Indian.

Both of these facilities were opened in 2003, as their large size allowed astronomers to see he and the other dwarf directly, using a number of ground-based and orbiting telescopes. For a long time they were considered large, but quite ordinary «failed stars» their masses, according to the old estimates, exceeded the Jupiter 50 and 28 times, and the temperature was impressive, but «normal» 700-1100 degrees Celsius.

Space good luck

The authors tried to clarify those values by watching how quickly all three inhabitants of the system move around each other, and the points at which they are located during times of maximum deletions and approaches. For this they used the VLT telescope and a number of other powerful ground-based observatories.

When the scientists analyzed new data, they were surprised to find that the mass of brown dwarfs in the Epsilon system Indian significantly underestimated – in reality they were 75 and 70 times larger than Jupiter.

Such a heavy object, as predicted by the classical theory of star formation must either be stars or be on the threshold of becoming «full» light and have several unusual properties. In reality, brown dwarfs of Epsilon Indians are quite normal and do not have abnormally high temperatures and other traits that are uncharacteristic to the celestial bodies of this type.

On the other hand, in recent years, astronomers have discovered stars such as EBLM J0555-57Ab, whose mass is slightly higher than the dwarfs in the Epsilon Indian. For some reason they were able to become full-fledged stars, while the companions GJ 845 this was not possible.

All this, as the researchers note, suggests that the mass of the future star or a brown dwarf cannot be used as the main criterion for determining what is a particular space object. Other factors, for example, the structure of the subsurface such «germ» of stars and their composition, can at least influence the fate of such objects than their weight, the scientists conclude.

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