A super-Earth class exoplanet orbits within the habitable zone of a red dwarf just 37 light years away.
Japan's Subaru 8.2-metre telescope operates at the Mauna Kea Observatory in Hawaii, observing the sky in the optical range. It was recently fitted with an IRD spectrograph to cover the infrared wavelengths. The new instrument will help to observe red dwarfs, which are much easier to distinguish in IR wavelengths than in visible ones. These old, small and faint stars account for most of the galactic population and are more often found in the vicinity of the solar system.
Red dwarfs may also have planets of their own, and if their orbits pass close enough to the parent star, in its habitability zone, the surface temperature may be comfortable enough to have liquid water, the main criterion for the development of life. For instance, the red dwarf GJ 1061, just 12 light years away, has a system of potentially habitable planets.
This is the kind of worlds the Subaru telescope, armed with a new spectrograph IRD, is looking for. It has spent several years searching for suitable red dwarfs, and recently began observing half a hundred of the most promising candidates. The first of these to spot an exoplanet was Ross 508. Preliminary reports of the find were made in May this year, and now a detailed, peer-reviewed publication about the discovery has appeared in the journal Publication of the Astronomical Society of Japan.
Ross 508 is a red dwarf located 36.5 light-years away, in the constellation Snake. It has a mass one-fifth that of the Sun and its habitable zone is much closer to the star than that of the Sun. The planet Ross 508b orbits near the inner edge of this region, about 20 times closer to its parent star than the Earth's orbit is to the Sun. A complete annual revolution of the Ross 508b takes only 10.8 Earth days. The mass of the planet is four times greater than Earth's, which allows us to classify it as a super-Earth.
The authors of the discovery note that this is the first successful example of super-Earth detection using data in the near-infrared range. Until now, such observations have been inaccurate and have only been able to distinguish larger exoplanets. The new instrument has provided the resolution needed, and there is no doubt that Ross 508 b is only the beginning. Reports of new worlds near our red dwarfs can be expected in the near future.
