Key Project 4 (Pan-Planets)

Key Project 4 (Pan-Planets)

The Search for Hot Jupiters Around Cool Stars

Dust map highlighting the seven individual fields periodically monitored by the Pan-Planets survey in the search for transiting extrasolar planets. The fields add up to a field of view of 42 square degrees. The blue and yellow circles indicate fields with long and short exposure times, respectively. The bright area in the map is the plane of the Milky Way.

Over the past decade, the search for transiting exoplanets has contributed an ever increasing fraction to the total number of exoplanet discoveries each year. This method requires the continual monitoring of stars to measure periodic, slight dimmings in their brightness as seen from Earth. After proper analysis, it can be determined from the stellar light curve whether the dimming is caused by a small, dark body transiting in front of and partly eclipsing the star they orbit. Further observations can confirm the planetary nature of that body—its size, mass and density, even the temperature and the composition of its atmosphere. Transits are therefore a very potent method to study exoplanets, even at a few thousands light-years from the Sun.

Taking advantage of its large field of view and good spatial resolution, Pan-STARRS1 monitored seven individual fields (42 square degrees in total) over a few months per year between 2009 and 2012 in order to obtain high-quality photometry for a large number of stars (about 10 times more M dwarfs than in the Kepler field). Overall, the Pan-Planets survey yielded about 4 million stellar light curves. MPIA researchers are now analyzing the data looking for so-called "hot Jupiters"—Jupiter-like planets in close orbitaround cool dwarf stars in order to constrain the fraction of such planetary systems.  


A Pan-Planets light curve (light measured on the vertical axis vs. time on the horizontal) of an exoplanetary system candidate. The plot shows the dimming of a K-type star (a star cooler and smaller than the Sun) as it is partially obscured by an orbiting "hot Jupiter." The planet has a radius very close to that of Jupiter and its proximity to the star results in an orbital period of only 2.66 days.

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