Telescope Gaia opened the first single white dwarf, which is contaminated with metals. This phenomenon is quite rare, because heavy elements, into the atmosphere of a star of this type, should just drown in it, sinking to the deeper layers, closer to the nucleus. The star, which opened the telescope was named GaiaJ1738−0826.
This reports the Research Notes of the American Astronomical Society.
A group of American and canadian astronomers under the direction of Karl Melissa from the Center for astrophysics and space Sciences studied the latest data release DR2 of the telescope Gaia European space Agency. The tool measured the brightness and color 1.7 billion of stars and the changes of these parameters for 500 million objects.
Scientists chose the star GaiaJ1738-0826 from the catalog based on the analysis of colors and absolute magnitudes of certain types of objects. The researchers then conducted spectroscopic observations of the white dwarf and found its spectrum lines, which correspond to calcium (Ca II). Thus, it was found that GaiaJ1738-0826 – metal polluted white dwarf with a radius and 0.012 to 0.6 solar masses. Effective temperature of its surface is 7050 degrees Kelvin, and a luminosity of only 3.3% of the luminosity of the Sun.
Based on the analysis of the ratio of the concentration of atoms of calcium to atoms of hydrogen, astronomers believed that GaiaJ1738-0826 in the current state must absorb approximately 2600 pounds of calcium in a second. Thus, in General, the star can “eat” about 160 thousand kilograms of matter every second, allowing on the basis of previous studies that the calcium is about 1.6% of the total number of metals that are absorbed.
However, the authors note that if the speed acres GaiaJ1738-0826 do is 160 kilograms per second, around it, probably, there must be a debris disk. However, archival data of the telescope “Spitzer” and inspection of the VISTA Hemisphere Survey do not confirm this hypothesis.
What are white dwarfs? This compact stars which are in the final stages of evolution. Despite the fact that a lot of these objects can be compared with the mass of the Sun, and their radius is almost 100 times smaller than him. Mainly in the spectrum of white dwarfs find the lines corresponding to hydrogen and helium. The first white dwarf enriched with metals, was opened in 1917 by American astronomer Adriaan van Maanen. At that time it was a very unusual phenomenon: a celestial body looked like a dwarf star, but its spectrum answered quite bright, massive star. For a long time researchers have tried to solve this riddle, till he came to the conclusion that in the atmosphere of a star there are a large number of metals – elements heavier than hydrogen and helium.
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