Exoplanet atmosphere in unparalleled detail

The complete dataset paints a picture of the molecular and chemical composition of a planet’s atmosphere 700 light-years from Earth.CSA explains in a press release.

Table showing the composition of the atmosphere of exoplanet WASP-39b.

Image: NASA/ESA/CSA/J. Olmsted/STScI

A team of astronomers from the University of Montreal led by Professor Bjorn Bennick first discovered sulfur dioxide, a molecule produced by chemical reactions triggered by ultraviolet radiation from its star.

This type of process, called photochemistry, has never been observed, until now, outside the solar system. On Earth, the protective ozone layer in the upper atmosphere is created in the same waynotes the press release published by the University of Montreal.

Other elements have also been detected in WASP-39 b’s atmosphere such as sodium, potassium and water vapor, confirming previous observations made with space and ground-based telescopes. Carbon monoxide was also detected.

Last August, he brought the same team Clear and accurate evidence of the presence of carbon dioxide (CO2) in the atmosphere of the same planet.

An artist's representation of what the WASP-39 b exoplanet might look like.

An artist’s representation showing what exoplanet WASP-39 b might look like, according to current knowledge of the planet.

Photo: STSCI

Perfect world

Planet WASP-39b orbits a sun-like star. The mass of this gas giant is about a quarter of that of Jupiter, and its diameter is 1.3 times larger.

Unlike the cooler, more compact gas giants that populate our solar system like Jupiter or Saturn, WASP-39 b orbits close to its star, barely an eighth of the distance between the Sun and Mercury. You complete the tour in just over four Earth days.

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  • The planet was discovered in 2011 using the transit technique, which shows a subtle, periodic dimming of the star’s light as the planet transits or passes in front of the star.
  • Its atmosphere appears puffy compared to other planets, a phenomenon likely related to its high temperature of about 900 degrees Celsius.
  • Due to its puffy atmosphere and frequent transits, WASP-39 b is an ideal target for conducting transmission spectroscopy, which allows determining the composition of a planet’s atmosphere through transits.
  • During transit, some of the light from the star passes through the planet’s atmosphere. This light is filtered by the atmosphere and allows its composition to be measured.
  • Thus, signatures of various chemical elements are found print Up in the air.

WASP-39b’s chemical inventory indicates that it was created from the collision and melting of many smaller bodies called planetesimals.

Other exoplanets in Ain Webb

This work demonstrates once again the great power of the James Webb Telescope’s instruments for studying exoplanets. In the coming months, the telescope will probe the atmospheres of Earth-sized rocky planets, such as those on Earth TRAPPIST-1 system.

Five articles devoted to exoplanets have been published on the site ArXiv (A new window) (in English).

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