The researchers obtained the first detailed images of the old star U Antliae. Also, the equipment of the ALMA telescope complex allowed astronomers to understand the structure of the "cocoon", consisting of discarded outer layers and a surrounding star.
Located in the constellation Pump, the star U Antliae was discovered in the late 1980s. The researchers were interested in how much the brightness of the light changed over several days. As it turned out, the star is a supergiant - one of the most massive stars at the end of its evolution. The masses of such objects vary from 10 to 70 solar, and the luminosity - from 30 thousand to hundreds of thousands of solar. At the supergiant stage, the luminaries, which have exhausted their supply of hydrogen "fuel", are rapidly expanding, actively throwing out into space the matter of their outer shells. The same happened in the case of U Antliae.
Meanwhile, the scientific world still faces many questions related to such stars. They were helped by images obtained by ALMA (Atacama Large Millimeter Array) - a complex of radio telescopes located in Chile's Atacama and combined into one astronomical radio interferometer.
Usually observations of supergiants are complicated by the density of the fiery "shroud" surrounding the stars. However, there is a relatively thin and transparent mantle of discharged gases around U Antliae. With the help of ALMA equipment, scientists have obtained a three-dimensional map of the "bubble" in which the star is located. It turned out that U Antliae surrounds a “cocoon” with a flaky structure. Thin and dense layers of gas are separated by empty areas.
This testifies in favor of the theory according to which aged stars do not shed their outer layers continuously, but episodically. One period of activity can last for several hundred years. The study showed that during one of these periods of time, the supergiant can lose mass, which is equivalent to 0.3-0.5% of the sun.
The results obtained in the framework of the study play an extremely important role for understanding the mechanism of the ejection of matter by stars and the "seeding" of the Universe with material that serves as "building blocks" for new planets. Findings dedicated to the discovery are posted on the website of the European Southern Observatory.
One of the radio antennas installed on the territory of the complex / wikipedia
We will remind, not so long ago, another group of astronomers announced the sudden disappearance of the supergiant N6946-BH1. As a possible cause of the phenomenon, scientists called gravitational collapse - the transformation of a star into a black hole. Astronomers believe that such unexpected transformations can occur with 30% of stars similar to N6946-BH1
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Ilya Vedmedenko