Researchers from NAOJ and the University of Tokyo have observed the atmosphere of super-Earth “GJ3470b” in Cancer for the first time in the world using two telescopes at OAO (Okayama Astrophysical Observatory, NAOJ). This super-Earth is an exoplanet, having only about 14 times the mass of our home planet, and it is the second lightest one among already-surveyed exoplanets. The observational data revealed that this planet is highly likely to NOT be covered by thick clouds.
The researchers expect that future detection of the specific composition of the planet’s atmosphere based on highly accurate observations with larger aperture telescopes, such as the Subaru Telescope. This planet orbits around its primary star very closely at a rapid rate. We don’t yet understand the formation process of such planets. If future detailed observations of the atmosphere detect any substance that becomes ice at low temperatures, it probably means that this planet was originally formed at a distance (a few astronomical units) from the primary star, where ice could exist, and moved toward the primary star thereafter. In contrast, if such a substance cannot be found in the atmosphere, this planet was quite likely formed at its present location (near the primary star) from its early stage. Thus, it is expected that the detailed observations of the atmosphere of GJ3470b can begin to reveal the mysteries behind the formation of super-Earths.
Details of results
It is very difficult to measure the radii of exoplenets, so in many cases we have information only about masses. However, if an exoplanet has a particular orbit of “Planetary Transit (Primary Transit)” where it passes in front of the primary star (parent star), we can estimate the radius of the planet. During the transit, the observed brightness of the star slightly drops depending on the size of the planet. So, we can estimate the radius of the planet by measuring the fading rate of light very precisely.
Read more at: Phys.org