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Press release: Inferno world with titanium skies

Nr. 176/2017 - 15.09.2017

Researchers detect titanium oxide in exoplanet atmosphere for the first time

(pug) An international team of researchers including the University of Göttingen has detected titanium oxide in an exoplanet atmosphere for the first time. Using the FORS2 instrument at ESO’s Very Large Telescope, they were able to gain unique information about the chemical composition as well as the temperature and pressure structure of the atmosphere on WASP-19b, an unusual and very hot world. The results were published in Nature.

WASP-19b has about the same mass as Jupiter, but is so close to its parent star that it completes an orbit in just 19 hours. Its atmosphere is estimated to have a temperature of about 2,000 degrees Celsius. As it passes in front of its parent star, some of the starlight passes through the planet’s atmosphere and leaves subtle fingerprints in the light that eventually reaches Earth. The researchers were able to carefully analyze this light and deduce that the atmosphere contains small amounts of titanium oxide, water and traces of sodium, alongside a strongly scattering global haze.

Titanium oxide is rarely seen on Earth. It is known to exist in the atmosphere of cool stars; in the atmosphere of hot planets like WASP-19b, it acts as a heat absorber. The presence of titanium oxide in the atmosphere of WASP-19b can have substantial effects on the atmospheric temperature structure and circulation. Furthermore, the parent star in this case is known to be an active star which exhibits large active regions on its surface in the form of starspots, much larger than the sunspots on our Sun. “Therefore, it is rational to expect that the host star activity might alter the observed transmission spectra of the exoplanet,” explains Dr. Mahmoudreza Oshagh from Göttingen University’s Institute for Astrophysics. “However, thanks to recent developments on the modelling of stellar activity, we were able to disentangle the signal produced by a planet’s atmosphere from the signal induced by stellar activity.”

The astronomers collected their data over a period of more than one year. By measuring the relative variations in the planet’s radius at different wavelengths of light that passed through the exoplanet’s atmosphere and comparing the observations to atmospheric models, they were able to extrapolate different properties such as the chemical content of the planet’s atmosphere. The results will allow much better modelling of exoplanet atmospheres and provide a stronger basis for the interpretation of future observations.

Original publication: Elyar Sedaghati et al. Detection of titanium oxide in the atmosphere of a hot Jupiter. Nature 2017. Doi: 10.1038/nature23651.

Dr. Mahmoudreza Oshagh
University of Göttingen
Institute for Astrophysics
Phone +49 551 39-13813