Heavy metals are detected for the first time 'evaporating' in the atmosphere of an exoplanet


Figure: artistic image of exoplanet WASP 121 b. The tremendous gravitational forces to which WASP 121 b is subjected due to the closeness of its star have drastically altered the shape of the planet, which features a notorious elongation that makes it look like a rugby ball. ©NASA, ESA and J. Olmsted (STScl).

An international team with the participation of the Centro de Astrobiología (CAB, CSIC-INTA) has discovered an exoplanet that is losing gaseous magnesium and iron through its atmosphere. These are the first observations in which so-called 'heavy metals' have been detected escaping from a 'Hot Jupiter', a type of giant, gaseous exoplanet orbiting very close to its star.

The exoplanet WASP 121 b orbits a brighter and hotter star than the Sun, WASP 121, located about 900 light-years from Earth.  The planet is so close to the star that its upper atmosphere reaches the incredible temperature of 2,600ºC, about ten times higher than any of the known planetary atmospheres. This extreme proximity causes the planet's upper atmosphere to be warmed by intense ultraviolet radiation.

In this study, published in the Astrophysical Journal, spectroscopic observations of WASP 121 (b) have been made with the Hubble Space Telescope (NASA/ESA) as part of the PanCET (Panchromatic Comparative Exoplanetology Treasure) program. These observations have made it possible to detect the unmistakable spectral traces of magnesium and iron gas ionized in the planet's exosphere. At these high altitudes, ionized magnesium and iron gas is not gravitationally bound to the planet and can escape into space.

As Jorge Sanz-Forcada, researcher at CAB and one of the authors of the study points out: "In this case, it is the first time that ionized metals (Mg II and Fe II evaporate). Until now ionized iron (Faith II) had been observed, but the emission came from the planet's atmosphere, not evaporating material".


Fuente: UCC-CAB

Fecha: 2019-08-02


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