NASA Discovers Primitive Atmosphere And Signs Of Water In Neptune-Sized Exoplanet ‘HAT-P-26b’

Scientists from the American space agency, NASA, have found a strong water signature in the atmosphere of a distant exoplanet. According to the researchers, the discovery could help in knowing more about a planetary system’s birth and development.

Astronomy Now reported that the exoplanet called HAT-P-26b is the size of Neptune and is located 437 light-years away. It orbits a star that is two times older than the Sun. The research team was able to study the exoplanet with the help of the Hubble and Spitzer Space Telescopes. They found that the exoplanet has a primitive atmosphere made mostly of helium and hydrogen.

According to Capital Wired, the study is one of the most detailed ones until now of a warm Neptune, i.e., of a planet that is the size of Neptune located close to its parent star. The research has indicated that the atmosphere of HAT-P-26b's is relatively clear of clouds and has a strong water signature. However, the exoplanet is not a water world. Furthermore, this is the best water measurement to date of an exoplanet this size.

The scientists also observed that HAT-P-26b probably originated either nearer to its parent star or later in the planetary system’s development phase, or both, as compared to Neptune and Uranus.

"Astronomers have just begun to investigate the atmospheres of these distant Neptune-mass planets, and almost right away, we found an example that goes against the trend in our solar system," researcher at NASA, Hannah Wakeford, said.

The research team was also able to use the water signature to calculate HAT-P-26b's metallicity. This indicates that they could find how rich the exoplanet is in all elements heavier than helium and hydrogen. The information also gives more ideas about how a planet is formed. The scientists found that the exoplanet’s metallicity is only around 4.8 times than that of the Sun.

The analysis has shown that the atmospheres of such exoplanets have a lot more diversity than scientists have previously expected, David K. Sing from the U.K.’s University of Exeter added. Moreover, the study also provides an insight into how planets can originate and evolve differently than those in the solar system.