Tag Archives: WASP-62b

WASP-62b, in James Webb’s continuous-viewing zone, has a clear atmosphere

James Webb’s “Continuous Viewing Zone” is the patch of sky where the satellite can point continuously at a target and so observe it most efficiently. Exoplanets within the CVZ that are suitable for atmospheric characterisation are thus of high importance, and so far WASP-62b is the only gas giant known within the CVZ.

Munazza Alam et al have now pointed the Hubble and Spitzer space telescopes at WASP-62b to see what its atmosphere looks like. Importantly, they find that WASP-62b has clear skies. This matters since cloudy or haze-filled atmospheres tend to produce flat spectra lacking any spectral features, and so don’t tell us much.

Here, Alam et al plot the spectrum near the sodium (Na) line, showing that it has a broad base, akin to that in the clear-skied planet WASP-96b. The broad base of the line means that it is being widened by “pressure broadening”, and that can only happen deep in the planet’s atmosphere where the pressure is high. And we can only see deep into the atmosphere if it is clear rather than cloudy.

Clear skies mean that spectral features produced by the molecules in the atmosphere should be readily detectable with JWST. Here Alam et al simulate what we expect to see with JWST, showing that Na, H2O, NH3, FeH, SiH, CO, CO2, and CH4 can all be detected.

They conclude by saying that: “As the only transiting giant planet currently known in the JWST Continuous Viewing Zone, WASP-62b could prove a benchmark giant exoplanet for detailed atmospheric characterization in the James Webb era.

Looking forward to WASP planets with JWST

The $6-billion James Webb Space Telescope “will likely revolutionize transiting exoplanet atmospheric science due to a combination of its capability for continuous, long duration observations and its larger collecting area, spectral coverage, and spectral resolution compared to existing space-based facilities”, write Kevin Stevenson et al in a new paper looking forward to Cycle 1 observations of exoplanets with JWST.

Of interest to us is at WASP that, of the “community targets” identified by Stevenson et al as the best targets for characterizing exoplanet atmospheres in Cycle 1, seven of the twelve are WASP planets, and in particular “the most favorable target is WASP-62b because of its large predicted signal size, relatively bright host star, and location in JWST’s continuous viewing zone”.

This independent assessment validates WASP’s program of finding exoplanets transiting relatively bright stars, where they make the best targets for ongoing detailed studies.

JWST is now not that far off, as Stevenson et al remind us with this timeline:

Timeline Of James Webb Space Telescope