There’s a lot of water on the hot exoplanet WASP-39b

Artist's concept of WASP-39b and its star (Image NASA, ESA, and G. Bacon (STScI))
Artist’s concept of WASP-39b and its star (Image NASA, ESA, and G. Bacon (STScI))

An article published in the journal “The Astronomical Journal” describes a study of the exoplanet WASP-39b. A team of researchers led by Hannah Wakeford of the University of Exeter and the Space Telescope Science Institute used the Hubble and Spitzer space telescopes to discover the traces of water in the atmosphere of this gas giant very close to its star. These planets are classified as hot Jupiters even if in this case its characteristics are comparable to Saturn’s. The most complete map of the atmosphere of an exoplanet obtained so far showed a considerable amount of water.

About 700 light years away from Earth, the exoplanet WASP-39b orbits the star WASP-39, which has a mass very similar to the Sun’s. WASP-39b’s mass is similar to Saturn’s so it was defined as a hot Saturn and it’s easy to compare the situation of the two planets and understand their profound differences.

The distance of WASP-39b from its star is about one 20th of the Earth’s from the Sun with the consequence that its year lasts only four Earth days. The researchers estimated that the temperature on the side of this exoplanet exposed to its star is almost 800° Celsius (about 1,430° Fahrenheit). Powerful winds carry the heat around the planet and the gas is so hot that it expands considerably so WASP-39b is bigger than Jupiter.

One of the exoplanet WASP-39b’s characteristics is the lack of high-altitude clouds, a great advantage in the observations. An article published in the journal “The Astrophysical Journal” in June 2016 suggested that it’s normal to find water in the hot Jupiter-type planets, but the presence of clouds can prevent their detection.

The result of the observations is that the exoplanet WASP-39b has about three times as much water as Saturn. It’s a surprising amount that was interpreted as an indication of this planet’s origin. According to the researchers, it formed much further from its star, where it was bombarded by icy materials that penetrated its atmosphere.

According to this reconstruction, only later WASP-39b moved closer to its star, perhaps destroying other smaller planets. If it formed in its current orbit, the icy materials would have been attracted by its star and it wouldn’t contain so much water.

The formation of hot Jupiters and planetary migration are two of the problems astronomers are studying and WASP-39b provided interesting clues. Hannah Wakeford stated that this exoplanet shows how planetary formation is more complicated than previously thought and that’s fantastic.

In the science field, surprises can provide clues to solve some mystery. For this reason the study of the exoplanet WASP-39b will continue and it was added to the targets of the observations programmed with the James Webb space telescope, currently scheduled for launch in 2019.

Leave a Reply

Your email address will not be published. Required fields are marked *