NASA's Kepler Space Telescope (launched in 2009) has discovered many extrasolar planets using the phenomenon that stars appear a little dark when they pass in front of them.Since this phenomenon can occur due to other causes, it is important to confirm whether it is a phenomenon caused by an exoplanet.After the observation of this space telescope ended in 2013 due to a failure, the K2 mission using the Gaia space telescope of ESA (European Space Agency) has started, and the confirmation of the new data is competing all over the world.

　From the raw data of the K2 mission and the Gaia Space Telescope, the research team selected 155 promising planet candidates by ultra-precision measurement of stellar brightness.Follow-up was carried out by imaging observations and spectroscopic observations of the candidate objects from the ground, and 60 new exoplanets were demonstrated.As a result, the number of exoplanets demonstrated in the K2 mission has greatly exceeded 300.

　Ultra-short period planets with an orbital period of 24 hours or less have many mysteries in their formation and evolution, and have recently begun to attract attention, but we have discovered three new ones this time.We also found 3 multi-planetary systems with multiple planets revolving and 20 rock planets with mass less than twice that of the Earth.Since there are many planets close to the earth, detailed observations are possible in the future, and it will be important for the development of astrobiology to explore the possibilities of space life.

　The K2 mission also ended operation in October this year due to fuel depletion, but the space telescope TESS (Transiting Exoplanet Exploration Satellite by NASA) has already started observation, and it is expected that many exoplanets will be discovered in the future. Will be done.

Paper information:[The Astronomical Journal] Sixty Validated Planets from K2 Campaigns 5–8