Most exoplanets smaller than Jupiter that are observed provide little to no evidence about the atmospheric makeup of the planet. However, that all changed when astronomers discovered an exoplanet that is roughly 430 light years away from earth that has some unusual characteristics. The planet which has been dubbed HAT-P-26b is being described as a “warm Neptune” with water vapor and evidence of “exotic clouds” in its atmosphere. Unlike the thousands of other exoplanets discovered by NASA, HAT-P-26b is unique in that astronomers were able to determine the composition of the planet’s atmosphere.
The Scientific American reports that astronomers were able to determine that HAT-P-26b has an atmosphere that is dominated by hydrogen and helium. The closest counterparts in our solar system would be Neptune or Uranus. The discovery was made using NASA’s Hubble and Spitzer space telescopes for viewing and observation.
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David Sing, an astrophysics professor at the University of Exeter and co-author of the new study about HAT-P-26b, says that the discovery of the “warm Neptune” showcases that there is “a lot more diversity” in the atmospheres of exoplanets than was previously thought.
“This ‘warm Neptune’ is a much smaller planet than those we have been able to characterize in depth, so 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.”
The report from the journal Science reveals that HAT-P-26b is different than most exoplanets discovered in that the team was able to identify signatures of water and clouds. Furthermore, the team determined that the atmosphere of the exoplanet had remained relatively unchanged since its formation.
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Hannah R. Wakeford of NASA Goddard Space Flight Center reveals that “this is the strongest water-absorption feature that we have ever measured.” Interestingly, the study also concluded that the exoplanet would have a very different looking sky than earth despite the water vapor and clouds. The clouds on HAT-P-26b are likely made of disodium sulfide instead of water vapor. Therefore, Wakeford says these “clouds would cause scattering in all of the colors.”
“This would be a very alien sky that you would be looking at. These clouds would cause scattering in all of the colors, so you’d get a kind of scattery, washed-out, gray sky, which is interesting, if you were looking through these clouds.”
Though the planet is being hailed as most closely resembling Neptune in size and makeup, it was revealed that many details of the planet are more similar to Jupiter when it comes to formation. According to Sky and Telescope, the unique observations of the “warm Neptune” offer clues into how these types of planets were formed. For HAT-P-26b, scientists believe that it may have formed later in the solar system’s formation rather than earlier which resulted in the planet receiving the bulk of its elements from the inner reaches of its solar system.
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The formation of the planet closer to its star would more closely resemble the formation of Jupiter than Neptune. Prior to the discovery of HAT-P-26b, Wakefield says that astronomers did not know that such small Neptune-like planets could be formed so close to their star. Instead, they had believed “smaller worlds to be formed further out, where they would accumulate clumps of icy debris and richer heavy elements during the formation in the [protoplanetary] disk.”
The team says that the “warm Neptune” is likely the first of many discoveries that will reshape the way astronomers look at the planet formation process. With the findings, scientists will be able to create new constraints for models of planet formation, opening the door to vast new discoveries.
[Featured Image by NASA/GSFC]