New Lightweight, Very Sunny Super-Earth Discovered

Lee Rannals for redOrbit.com – Your Universe Online

Researchers writing in the Astrophysical Journal say they have discovered one very light and sunny super-Earth.

Dubbed GJ3470b, the team says the planet is about 14 times the mass of our own planet but is the second lightest of the existing exoplanets that have already been surveyed. Their data revealed that this planet is most likely not covered by thick clouds but is a place where sunscreen would be a necessity.

GJ3470b orbits its primary star very closely and at a rapid rate, circling around its star at about 28 times less than the distance between the Sun and Earth. According to the study, GJ3470b completes its orbit around its star in just 3.3 Earth days.

The team used two telescopes at Okayama Astrophysical Observatory (OAO) in order to capture data about this planet. They measured the brightness dropping rates of the stars in four colors, which enabled them to estimate each radius by color for the planet. The differences of radii between colors could be due to the reflection of the atmospheric characteristics of the planet. As the light from the primary star is transmitted through the atmosphere of the planet, certain wavelengths of light are absorbed by atmospheric molecules, causing the difference of apparent radii for each observation wavelength.

“Suppose the atmosphere consists of hydrogen and helium, the mass of the atmosphere would be 5 to 20 % of the total mass of the planet,” said Akihiko Fukui, who led the team. “Comparing that to the fact that the mass of Earth’s atmosphere is about one ten-thousandth of a percent (0.0001%) of the total mass of the Earth, this planet has a considerably thick atmosphere.”

The astronomers said the differences in radii by colors were what helped them determine that thick clouds do not encompass this planet. The composition of the planet’s atmosphere could be detected without being blocked by its clouds. Determining whether there is any water or methane could mean this planet formed far enough away from its primary star to allow ice to exist. More detailed observations of its atmosphere could help reveal closer details about this planet’s formation.

“We expect to obtain important clues for figuring out how super-Earths were formed through observations of the atmospheric component of GJ3470b,” said Fukui.

Astronomers writing in the journal Astrophysical Journal Letters said earlier this month that they have captured images of the least massive exoplanet discovered so far. Direct imaging of planets is tough for scientists to do, and only a few planets have been observed directly this way.

Hunting exoplanets is no longer just for astronomers who have rare access to large telescopes these days. Planetary Resources announced yesterday that it would be upgrading its ARKYD space telescope to hunt exoplanets and give the public a chance to spend some time with it through its kickstarter campaign.

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