Astronomers found that the exoplanet WASP-12b is close to its star and it will soon be destroyed. This is the first planet that was discovered this effect. The discovery will shed light not only on the fate of planetary systems, but on the internal structure of stars.
Achievement is described in a scientific paper published in the Astrophysical Journal.
WASP-12b belongs to the hot Jupiter. The so-called exoplanets the size of Jupiter, located very close to their stars. WASP-12b makes a full revolution around the sun for just 1,09 earth days.
“Since the opening of the first hot Jupiter in 1995 – open, awarded the Nobel prize in physics for 2019, we wondered how long you can survive this planet,” says co-author Joshua winn (Winn, Joshua) from Princeton University.
the Death of the titans
the fact that close to the planet-the giant is in the bowels of the stars of real tides. Rising and falling waves of gas being decelerated by the friction on the surrounding material. As a result of gravitational energy of the planet is converted into heat generated from this friction. Losing energy, the celestial body comes closer to their sun. This calls inside the last more powerful tides, and repeated with a new force.
of Course, the sun causes the tides in the depths of exoplanets. And in the end, the planet approaches the star, so close that the movements of matter just tear the doomed world, turning it into an extended gas cloud.
At the same time-giant planets can stay rocky core, holding the remains of the gas. Perhaps some of the famous scientists supertall and mininature represent the “heart” destroyed hot Jupiters.
This picture is drawn by theorists. But still failed to find at least one planet, which is close to their star fast enough so the observers could detect and measure this movement.
it is Unclear even whether it is possible to count on that the existing level of technology. The experts were undecided how much time it should take the process of rapprochement with the star. It could be millions and billions and even trillions of years. For comparison, the current age of the Earth (and at the same time – her remaining life time) is about 4.5 billion years, and the Big Bang occurred about 13.8 billion years ago. The first representatives of the genus Homo split from the Australopithecines about 2.5 million years ago.
Facts and hypotheses
Hope for an answer brought the planet WASP-12b, located at a distance of 600 light years from Earth in the constellation of Auriga. She was discovered in 2008 by the method of transits. “News.Science” (nauka.vesti.ru) wrote extensively about this approach that gave humanity more than 70% of the approximately 4100 open today worlds.
Recall that the transit is the exoplanet passing between its sun and earth observer. Exoplanet eclipses some of the light from the stars, and the observed brightness in a characteristic way falls. These periodic darkening and indicate the existence of a distant world.
In 2017, astronomers have discovered that the time between two consecutive transits of WASP-12b is reduced by 29 2 milliseconds per year. This could indicate that the planet approaches the star. But there were other options.
for Example, the Earth’s orbit gradually rotates around the Sun, as shown in the animation below (a full rotation is completed over 112 thousand years). This process is known as the precession of lines of apsides. It could be assumed that the interval between the transit of WASP-12b is changed due to the same phenomenon, not the proximity of the planet to the star.
it was also Not excluded that the reduction of the interval between the transits – apparent. In the seventeenth century the Danish astronomer OLE Roemer found that the ZATmenia eclipses of Jupiter’s satellites by the parent planet observed earlier, when the giant is closer to the Ground, and later, when he’s on. So scientist discovered that the speed of light is not infinite, and even measured it (for the first time in history). The light had to travel different distance, so the observer saw the Eclipse at different times. It was impossible to exclude that this effect worked and in the case of WASP-12b.
planet on the edge of the abyss
Careful observation on several instruments, the results of which are presented in a new article, allow us to discard alternative hypotheses. Astronomers have measured the duration of the secondary Eclipse (when the planet is hidden behind the disk of the star) and found that it varies the same as the duration of the transits. This helped to eliminate the hypothesis of precession of the line of apses. By measuring the velocity of the planet, the researchers refused and the version with the effect of the römer. There was one plausible explanation: the approach of the planet to the star.
According to the authors ‘ calculations, WASP-12b remained about three million years. This is important information for understanding the evolution of planetary systems. If hot Jupiters exist for so short a time, in many observed systems, they could be destroyed.
in addition, the new data will help to better understand the internal structure of stars. Deadly because of the speed of convergence, we recall, depends on the strength of the tides caused by the planet in the star’s interior.
By the way, earlier “News.Science” (nauka.vesti.ru) wrote about some of the worlds less likely to fall onto the star after its transformation into a white dwarf. We also talked about evaporating planets.