Mar. 24, 2016

Looking for clues about the formation process
The abundance of water and other molecules in the atmospheres of exoplanets may help to determine their formation mechanism, as Kamen Todorov explains: “Planets are usually formed within a disk of gas and dust which surrounds a very young star, no more than about 10-15 million years.” Because of physical processes within that disk, planets that form in different parts of the disk (close to the star or further away) may have different total amounts of carbon and oxygen, also depending on the exact process of formation. “Comparing the ratio of carbon and oxygen atoms in the atmosphere of a planet or a brown dwarf can give us clues about how it formed and where in the disk,” says the astrophysicist: “Water, carbon dioxide, carbon monoxide and methane are the most common molecules that carry C and O, so we are most interested in counting those.”

In this case, the data were not quite good enough to determine the carbon dioxide, carbon monoxide and methane abundances, and hence the C/O ratio, well. But Kamen Todorov plans to extend his project to look into other similar objects that are even hotter or less hot and examine how the water abundance and C/O ratio change with temperature and distance from the central star. And Michael Meyer, leader of the NCCR PlanetS research project 1 “Disks & Planets” says: “We hope to coordinate our efforts in this area through the NCCR PlanetS and apply similar techniques to other directly imaged planets.“ (bva)

Image: The “Super-Jupiter” Kappa Andromedae b, shown here in an artist’s rendering, circles its star at nearly twice the distance that Neptune orbits the sun.