What Astronomers Found on HAT-P-26b

Scientists at the University of Exeter have discovered peculiar aspects of the Neptune-sized exoplanet HAT-P-26b using NASA’s Hubble and Spitzer Space Telescopes. Their findings contribute to our knowledge of the diversity of planets as well as how they are formed.

As the planet — which is around 437 light-years from earth — passed in front of its sun, allowing the telescopes to measure it, scientists discovered an atmosphere rich in helium, hydrogen, and water vapor. Hannah Wakeford, co-leader of the new study and postdoctoral researcher at NASA’s Goddard Space Flight Center (GSFC), said that this atmosphere would result in “a very alien sky […] a kind of scattery, washed-out, gray sky.”

The planet is also of interest because of its formation. In Earth’s Solar System, metallicity (astronomy terminology for anything heavier than helium) tends to decrease as mass increases, but HAT-P-26b defies this pattern. While it is about the size of Neptune, its metallicity is more inline with Jupiter.

So, why does this matter?

David Sing, a professor at the University of Exeter said, “this new discovery about its atmosphere feels like a big breakthrough in our pursuit to learn more about how solar systems are formed, and how it compares to our own” because “This exciting new discovery shows that there is a lot more diversity in the atmospheres of these exoplanets than we have previously thought.” And, while thousands of exoplanets have been discovered, we know relatively little about the compositions of their atmospheres.

This is the first in what promises to be a series of breakthroughs that will emerge as new telescopes launch this upcoming October. The James Webb Space Telescope (JWST) will allow us to explore further with a mirror that has a diameter of 6.5 meters in comparison to the Hubble-Telescope’s 2.4 meter. In addition to this, the Transiting Exoplanet Survey Satellite (TESS) will provide “detailed characterizations of planets and their atmospheres”and is expected to survey more than 200,000 planets during its 2 year mission.