Researchers report on the hot atmosphere of Jupiter HD 189733b

Scientists from the Institute of Laser Physics of the Siberian Branch of the Russian Foundation for Basic Research have shown the atmosphere of the “hot Jupiter” known HD 189733b and have studied what prevented the stable acquisition of hydrogen in the atmosphere of the planet. They also describe the physico-chemical characteristics of this planetary system. They presented this topic at a symposium of the Asia Pacific Geophysical Society in August 2023, and the work is published in. The Astrophysical Journal.

Exoplanets are planets beyond the solar system. The most studied of them are from the family called hot Jupiters. They are comparable to the Jupiterian exoplanets in terms of size and mass, but they orbit their star 10 times closer than Mercury orbits the sun.

Such a close distance and high temperature cause the air to leave the planets at ultrasonic speed, and the flow of the atmosphere, and its content, can be studied with the help of the flow spectroscopy method. This method includes the registration of the absorption of stellar radiation by the planet’s atmosphere and enables the definition of what elements are present in the atmosphere, allowing researchers to make conclusions about the speed and density of different elements.

HD 189733b has attracted researchers and telescopes for less than a decade. The planet became famous for its blue color, which is caused by glass (silicate) rain – particles of silicates raised in the air. One of the most interesting mysteries of this planet “disappeared” is the movement of the hydrogen Lyα line – the absorption measurements at this wavelength diapason turned out to be inconsistent.

More obvious is the case with the IK-line of metastable helium 1083 nm – the transit in its position was observed twice, but with a different amplitude. Those changes suggest a very different regime of matter output for the planet HD 189733b, and computer modeling is the best way to investigate the causes of the changes.

One of the most advanced tools for measuring complex elements in the atmosphere of exoplanets and interpreting the absorption of transits on Earth was created and developed by scientists from the Institute of Laser Physics of the Siberian Branch of the Russian Foundation for Basic Research.

After using it on HD 189733b, scientists found that the main reason for the unstable absorption in the hydrogen Lyα line is the high activity of the host star, which is reflected by the increase in the radiation flux in the ultraviolet region (FXUV, erg∙cm-2с). -1Å-1 for 1 АЕ) and the rate of mass loss of stellar material. It was found that changes in those elements can cause not only a variable absorption in the hydrogen line due to the creation of strong neutral atoms in the strong stellar wind, but also a different absorption in the metastable helium line.