The red supergiant Antares is almost twice as cold as the Sun. Moreover, it is about 900 times larger than our luminary and 15 times more massive. In combination with a moderate distance to Earth - 600 light years - this makes it a star of the first magnitude, which, however, can only be admired in the southern regions of our country: at the latitude of Moscow, it barely rises above the horizon.
The brightness of Antares makes it an object of close attention of astronomers - it is one of the most convenient stars for studying, not counting, of course, the Sun. In addition, this diamond (or ruby?) Of the constellation Scorpio is at a dramatic stage in its life. Fuel reserves in its depths are coming to an end, and quite soon by astronomical standards (say, hundreds of millions of years), it will end its existence in an all-consuming supernova explosion.
On August 16, a team of astronomers led by Keiichi Ohnaka of the Institute of Astronomy at the Catholic del Norte University in Chile published a study in the journal Nature in which they presented a new map of the supergiant's atmosphere.
Scientists used the VLT observatory. This is a system of four eight-meter telescopes that can be combined into a single whole, working as one instrument and at the same time making up the largest optical telescope in the world (hence the name Very Large Telescope, or VLT).
This grand astronomical instrument, installed in the Atacama Desert in Chile, has delighted us with discoveries more than once. For example, with its help it was possible to obtain a weather map on a brown dwarf, photograph a unique nebula in the constellation Hydra and find an earth-like planet similar to Tatooine.
This time, the researchers used the full power of the "very large telescope" to understand what is happening in the atmosphere of Antares. The fact that the spectral lines of carbon monoxide can be observed in it played into the hands of scientists. This super-strong molecule is found even in the atmosphere of the Sun, and even more so in the cooler atmosphere of a red star.
The behavior of the CO spectrum has allowed astronomers to estimate the density and velocity of plasma streams. And here the scientists were in for a surprise: the density was significantly higher than expected. This means that much more matter is pushed out from the interior of the star to the surface than is possible according to existing ideas.
The process that lifts masses of gas from incandescent depths to a relatively cold surface is called convection. To feel and understand its work, it is enough to hold your palm over the central heating battery. Hot gas is lighter than cold gas, so a powerful updraft forms over any heater - a battery, frying pan, or the inner layers of a star.
Promotional video:
Accurate models exist that calculate the intensity of convection based on the energy release of a star. And these models say that this process cannot lift that much gas into the Antares atmosphere. This should mean that a powerful and previously unknown to astronomers force is acting in the interior of the star. The authors find it difficult to name its nature.
They say more information needs to be collected, which should be helped by new observations and, possibly, animation that recreates the movement of plasma streams. So in the future, we will probably see a cartoon about a mysterious star.
We add that this is far from the only mystery associated with the eruption of stellar matter into space. Even our close and dear Sun, which is much more accessible to study than Antares, is in no hurry to lay out all its cards on the table.
For example, the reasons for the existence of the now-known solar wind are still not fully understood. There is no exhaustive model of its formation, and those that exist admit solutions in both directions: both the solar wind and, conversely, the fall of the interstellar plasma on the Sun. The fact that our luminary chose the first option may be an accident. Or maybe not. This is not yet known. Space, perhaps, so attracts people precisely because of its deepest unknown.