A search for planets in the old open cluster NGC 6791

Abstract

\n We describe the results of a search for \n transit-like events caused by giant planets occulting\n stars in the old, metal-rich open cluster\n NGC 6791 based on BVI-colour photometry from eight nights of \n observations with the\n 2.54 m Nordic Optical Telescope. To extract the light curves \n we have used both PSF photometry (<sc>daophot</sc>) and the difference \n imaging technique (<sc>isis</sc>). We have re-analyzed\n observations from earlier campaigns to search for multiple\n transits, determine periods of long-period \n variables, and detect eclipsing binaries. \n We confirm 20 known variables and have discovered 22 new low-amplitude \n variables with amplitudes in the range 7–40 mmag and periods\n 1–16 days. We have found the primary and secondary \n eclipses of two eclipsing binaries based on the new and\n older photometric campaigns. The search for transit-like events has turned up\n a few single-transit candidates. The transit depths are\n 10 mmag in both the V and I filters over periods of 1.0–2.5 hours, \n but future observations are required to see whether identical\n transit-like events recur in these same stars. \n \n \n