Investigated using radio telescope complexALMA, located in the Chilean Atacama Desert, the quadruple star system truly astounded astronomers. It turned out that it has one feature that has never been encountered in practice before and has existed until this point only in the minds of theorists. Nevertheless, the results of the observations, published in the journal Nature Astronomy, once again prove that space is full of mysteries that are just waiting to be discovered.
Quadruple star systems containing two eachpairs of double stars are not really unusual. Yes, they are quite rare, but still occur. Also, the presence of a protoplanetary disk in the system (rings of gas and dust from which future planets are formed) is not a revelation. The studied HD 98800 system is located approximately 146 light years from Earth in the constellation Bowl and has all these features. What surprised scientists so much? Incredibly unique protoplanetary disk, which is in it.
The HD 98800 system consists of four stars,broken into pairs - internal and external. The stars of the inner pair, called BaBb, are in close proximity to each other at a distance of about 1 astronomical unit (1 AU = distance from the Earth to the Sun). The luminaries of the outer pair, AaAb, are located much further from each other - in 54 astronomical units, which is much farther than the distance between Pluto and the Sun (about 40 AU). The outer pair of luminaries is of no interest. The most interesting thing in the system is the internal pair of stars and the protoplanetary disk surrounding them.
Typically, the protoplanetary disk is located insame plane as the orbital plane of the other objects of the system. As it turned out, this rule does not work with the HD 98800 system. The latter has a disk that is oriented exactly perpendicular to the plane of rotation of its constituent stars. In other words, instead of a conditional horizontal west-east plane, the disk is located in a plane from north-south. Prior to this discovery, systems like HD 98800 existed only in theory.
"Protoplanetary disks rich in gas and dustobserved around almost all young stars. We know that at least 1/3 of the disks located on single stars contain planets. Some of these planets under the action of certain forces can shift relative to the axis of rotation or the equator of the star. We have always wondered whether such bizarre dynamics is possible in systems with double stars. Computer simulation shows that in such systems development can go along two paths: either the planets will rotate in the same plane with the stars, or perpendicular to them. But we didn’t have evidence before, ”commented lead study author at the University of Warwick (UK), Grant Kennedy.
Astronomers knew about the existence of the HD 98800 systemfor several years now. In the framework of previous studies, attempts were made to observe the movement of the inner pair of luminaries. However, thanks to the use of a powerful array of “Atakam large millimeter-range antenna array”, the Kennedy team managed to break through dense layers of dust and gas of the disk just now. The use of ALMA made it possible to get the clearest picture of how the HD 98800 system looks, and also to reveal the amazing orientation of the protoplanetary disk in it.
Estimated view from the surface of a hypothetical exoplanet inside the protoplanetary disk in the HD 98800 BaBb system
According to the authors of the study, ifsuppose that a forming exoplanet is located inside the protoplanetary disk, the sky from its surface would simply look incredible. Being on such a planet, a ring of dust and gas from a protoplanetary disk would look like a bright band rising from the horizon, passing right above your head and then hiding from the opposite side. At the same time, the two stars of the system would periodically hide behind the disk, and then come out again because of it, sometimes casting two broad shadows on the surface.
"This is an amazing result of observations," - says the astronomer of the California Institute of Technology Konstantin Batygin, who did not participate in this study.
"Such a configuration is something that canexpect from the combinatorial effects of gravity and internal scattering inside the protoplanetary disks. The discovery of the first such system suggests that the previous simulation actually turned out to be very accurate. Now there is no doubt that in the future we will be able to find the same systems. ”
Astronomer Princeton University DanielTamayo, who also did not participate in the study, shares the joy of the Kennedy scientific group, describing the work published in Nature Astronomy, as "an incredible article about a definite and beautiful discovery."
"It's funny that such a mathematically bizarreThe model of the dynamics of a polar planetary disk around a binary system is a fairly stable configuration. Initially it was not clear whether it can even appear in nature. In earlier studies it was said about the discovery of a number of oblique protoplanetary disks, but this was the first time that such an option was encountered. ”
The next test for astronomers will be to search for similar systems, but at different stages of their evolution.
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