Hubble’s tale of two exoplanets: WASP-67b and HAT-P-38b

NASA have put out a press release entitled: “Hubble’s Tale of Two Exoplanets: Nature vs. Nurture”.

The article compares WASP-67b and HAT-P-38b, noting how similar they are in size and temperature, both orbiting similar stars at a similar orbital distance. But then Hubble’s Wide Field Camera 3 found that WASP-67b has a very cloudy atmosphere whereas HAT-P-38b has much clearer skies.

From the press release: Perhaps one planet formed differently than the other, under a different set of circumstances. “You can say it’s nature versus nurture,” explains co-investigator Kevin Stevenson. “Right now, they appear to have the same physical properties. So, if their measured composition is defined by their current state, then it should be the same for both planets. But that’s not the case. Instead, it looks like their formation histories could be playing an important role.”

“Astronomers measured how light from each parent star is filtered through each planet’s atmosphere. HAT-P-38 b did have a water signature indicated by the absorption-feature peak in the spectrum. This is interpreted as indicating the upper atmosphere is free of clouds or hazes. WASP-67 b, has a flat spectrum that lacks any water-absorption feature, suggesting most of the planet’s atmosphere is masked by high-altitude clouds.”

The NASA press release has been picked up and reported on several dozen science-related websites.

Credits: Artwork: NASA, ESA, and Z. Levy (STScI); Science: NASA, ESA, and G. Bruno (STScI)