A chemical compound (TiO) that is a component of rock and is found in the exoplanet's atmosphere.Titanium oxide (TiO) is a chemical compound made of one titanium atom and one oxygen atom. On Earth, it is a solid mineral often used as a white pigment, but in the atmospheres of hot exoplanets, it exists as a gas. Its presence is significant because TiO is a strong absorber of visible and ultraviolet light, acting like a blanket that can heat a planet's upper atmosphere to extreme temperatures, sometimes exceeding 2000°C.
Titanium oxide was first detected in the atmosphere of an exoplanet in 2017, in observations of the hot Jupiter WASP-19b, using the FORS2 instrument on the Very Large Telescope. The detection was reported by a team led by Elyar Sedaghati.
In a gas phase, TiO molecules absorb photons across a wide range of wavelengths, particularly in the blue and ultraviolet. This absorption converts light energy into heat, warming the atmospheric layers where the gas resides. Because TiO is heavy, it tends to sink, but in very hot atmospheres, convection and mixing can keep it aloft, creating a thermal inversion—a layer where temperature increases with altitude, opposite to what is typical on cooler planets.
Astronomers use TiO absorption features to probe the temperature structure and circulation patterns of exoplanet atmospheres, helping to classify these worlds and understand their weather.
On Earth, titanium dioxide (TiO2, a different compound) is the main ingredient in many sunscreens, but its cousin TiO in space acts as a powerful heat-trapping gas, not a shield.























