In the atmosphere of a hot Jupiter found no Rayleigh scattering

The astronomers found that in the atmosphere of hot Jupiter WASP-79b is not observed Rayleigh light scattering of stars. This phenomenon is unusual and does not yet have the explanations which the scientists need to find a future space telescope “James Webb”. Preprint published on the portal arXiv.org.

The type of exoplanets hot Jupiters represent gas giants with masses in the range of 0.36-11.8 Jupiter masses (the upper boundary is the level at 13.6 Jupiter masses, in this case, the body is considered to be a brown dwarf), which have relatively short orbital periods (from one to hundreds of earth days). They are located close to their stars, which makes it easy to detect them with the techniques radial velocities or transits. Because of the proximity to the stars of the atmosphere of hot Jupiters are heated to high temperatures, in addition, they may be missing the concept of day and night because of the situation of tidal capture. Interest from a scientific point of view, such bodies are due to the complex atmospheric dynamics and various chemical processes.

Studies of the atmospheres of hot Jupiters has shown that many of them contain clouds or haze. Particles of aerosols have a significant influence on the spectroscopic study such exoplanets in the near-infrared or optical range, as cause Rayleigh scattering (due to which the earth’s sky appears blue) or scattering Mi light of their parent stars. Because of this, it is difficult to understand what chemical elements are found in the deeper layers of the atmosphere (this can be sodium, potassium or water vapor).

WASP-79b was opened in 2012 in the star system of spectral class F, which is one and a half times more than the Sun and 1.38 times more massive than him. The star is at a distance of 780 light years from Earth in the constellation of Eridanus. The exoplanet completes one orbit around the star for 3.6 earth days in an unusual polar orbit, has a mass of 0.9 mass of Jupiter and a radius of 1.7–2.1 the radius of Jupiter. Its equilibrium temperature is 1800 Kelvin, the outer layers of this hot Jupiter is expanded due to the powerful streams of radiation from the sun.

A team of astronomers led by Christina Cotten (Kristin Sotzen) of the applied physics Laboratory of Johns Hopkins University published the results of observations of WASP-79b at wavelengths from 0.6 to 5 microns with the help of space telescopes “Hubble” and “Spitzer” and one of the ground-based 6.5-meter Magellan telescopes. We used a method of transmission spectroscopy, which consists in the fact that at the time of the event transit of the exoplanet across the stellar disk, part of its light passes through atmosphere and is absorbed by various chemical elements, which is reflected in the spectra of transmittance and allows us to understand the composition of the atmosphere.

It turned out that in the atmosphere of extrasolar planets is not observed Rayleigh light scattering stars, its opacity does not increase with the change in the wavelength at which the observations are made. For an observer on WASP-79b sky it would seem yellowish. Observations suggest about the presence of water vapor in the atmosphere of extrasolar planets and to obtain upper limits on the content of iron hydride (FeH), CO and CO2, traces of sodium and oxide of vanadia was not found. All these properties of the WASP-79b made it one of the major initial goals for a future space telescope “James Webb”, which will study her for 42 hours in four different observation modes, which will allow to obtain more detailed transmission spectra, to identify cloud layers in the atmosphere and pinpoint its composition.

Earlier we talked about how in the atmospheres of hot Jupiter first found potassium, a couple of yttrium and chromium and the aluminium oxide, and where the extreme black exoplanet of a similar type.

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