Water Found In Primitive Atmosphere Of Distant 'Warm Neptune'
A detailed study of an exoplanet reveals that it may have a primitive atmosphere composed mainly of helium and hydrogen. A new study shows the most detailed analysis of an exoplanet that's very close to our own Neptune in size.
Exoplanets continue to be a relevant topic of interest when it comes to space exploration. Now thanks to a joint effort between NASA and a team of scientists from various universities such as the University of Maryland and University of Exeter, a new study is showing the most detailed analysis of a warm Neptune to date.
The particular warm Neptune discussed in the study isn't the only Neptune-sized exoplanet discovered of late. Similar to other warm Neptunes, exoplanet HAT-P-26b, located at about 437 light-years away from Earth and discovered in 2011, bears a similar size and mass to our solar system's Neptune but is closer to its host star, which is about twice as old as our own sun.
Using data gathered from the Hubble and Spitzer Space Telescopes, authors of the study reviewed specific information from the exoplanet's transits to its own sun as well as its strong water signature, which is said to be the best measurement of water on an exoplanet of this size.
When a planet or exoplanet transits, it passes in front of its host star, and a fraction of the starlight gets filtered through the planet or exoplanet's atmosphere. When this happens, some wavelengths of light are filtered while others are not.
By looking at the starlight signatures as a result of the transit and measuring its elemental composition by looking at the exoplanet's strong water signature, scientists were able to reveal that this particular planet has a high heavy elemental abundance, which points to the possibility that HAT-P-26b was formed rather differently compared to Neptune.
Warm Neptune Is More Like Jupiter
In our own solar system, Neptune and Uranus have much richer and greater heavy elements as compared to Jupiter and Saturn, which are mostly composed of hydrogen and helium. This is believed to be a result of Jupiter and Saturn being formed in the warmer areas of the solar system where they were less bombarded with ice debris that likely brought the heavy elements, as compared to Neptune and Uranus, which were possibly hit with a lot of ice debris when the solar system was just forming.
Now, looking at this familiar theory as to how our own solar system was formed, two other distant planets also fit the description of having bigger planets with lower metallicities, namely HAT-P-11b, which is another warm Neptune, and WASP-43b, which is twice as large as Jupiter.
HAT-P-26b, however, with a metallicity of just about 4.8 times the metallicity of our sun, runs closer to Jupiter rather than Neptune. This, perhaps pointing to the possibility that HAT-P-26b was formed closer to its host star, formed late into the development of its planetary system or both.
Scientists believe that as much as they have amassed a large amount of information on exoplanets, there is still much to learn as they continue to be surprised with new information on just how diverse exoplanets could be.