When scientists look for exoplanets out in the Universe, a considerable amount of time is being spent looking for the holy grail – an Earth twin that matches our home in size, mass, and habitability. Most of the exoplanets found so far are much larger than our planet, simply because they are easier to see, but as technology improves and we have more time to analyze data, smaller planets have come to light. A newly discovered planet has just been announced from scientists at the Harvard-Smithsonian Center for Astrophysics: a gassy planet with an Earth-like mass. A newly discovered planet has just been announced from scientists at the Harvard-Smithsonian Center for Astrophysics: a gassy planet with an Earth-like mass. The paper has been submitted for publication in The Astrophysical Journal, though the results were presented today at the 223rd Meeting of the American Astronomical Society by lead author David Kipping.
The planet KOI-314c is about 200 light years away and orbits a red dwarf star, which has considerably less mass than our sun and belongs to a different spectral class. The planet has an orbit of only 23 Earth days and its proximity to the star puts the surface temperature at an estimated 220 F (104 C). Unfortunately, this is much too hot to sustain the kind of life that we can detect. As a comparison, the highest temperature ever recorded on Earth was 136 F (57.8 C).
The diameter of KOI-314c is about 60 percent larger than Earth, though it is strikingly similar in mass. This is the smallest and lightest planet to have both of these parameters measured. Researchers have been able to deduce that the planet is quite gassy with an atmosphere of helium and hydrogen that could be hundreds of miles thick.
The mass of the planet was determined using a relatively new method called transit timing variations (TTV). It has only been in use since 2010, but allows astronomers are confident that it provides accurate measurements of low-mass planets. As the planet in question transits another planet within the system, the fluctuation in gravity forces the planet to “wobble” slightly and it alters the time it takes a planet to transit, which means it changes the amount of time it takes for the planet to cross in front of the star. The team monitored the light KOI-314c against its neighbor KOI-214b which matches it in size, though it is about four times more dense.
This discovery is exceptionally cool because it wasn’t even what the astronomers were searching for. The team was combing through data obtained from the Kepler Space Telescope in search for exomoons around potentially habitable planets when it came across KOI-314c. Though the team initially reports being disappointed that the planet wasn’t an exomoon, the significance of their discovery more than made up for it.
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