Astronomers map exoplanet in 3D for first time
Astronomers have mapped the exoplanet WASP-18 b in 3D. The exoplanet is tidally locked, with the dayside hot enough to split molecules of water.
An international team of astronomers have produced a three-dimensional map of a world in orbit around another star, or an exoplanet for the first time. The well-studied exoplanet is at a distance of about 400 lightyears from the Earth, and is a gas giant about ten times the mass of Jupiter in a close orbit around its host star. There is no comparable world in the Solar System. WASP-18 b is tidally locked to its host star, just like the Moon is tidally locked to the Earth. One side of the planet constantly faces the Sun, leading to extreme temperature gradients. Observations by Webb have been used to map the temperature gradients on the planet before.
The same team has developed the 2D model further into a 3D model using a technique called spectroscopic eclipse mapping, which demonstrates the potential of the technique to leverage the exquisitely sensitive observations by the James Webb Space Telescope (JWST), the most powerful and expensive astronomical instrument deployed by humans in space. The technique allows astronomers to study exoplanets that are in close proximity to the host star, and are outshined by their lumosities. The technique has previously been used to observe features on planets within the Solar System, including the Great Red Spot on Jupiter which is a persistent storm that can swallow up more than two Earths in the equatorial region of the gas giant.
Spectroscopic Eclipse Mapping
Over three dozen researchers from 20 institutes from around the world were part of the collaborative efforts. Detecting such worlds is itself a challenge, let alone characterizing them and mapping their atmospheres. The researchers examined and compared the light from the system before and after the exoplanet passes behind the host star from the vantage point of the Earth. Astronomers can then derive a spectrum of the planet, revealing the brightness of different colours, which can then be converted to temperatures in three dimensions, latitude, longitude and altitude. The researchers were able to determine that the day side of the planet gets hot enough to split water. A paper describing the research has been published in Nature Astronomy.