Transit detections of extrasolar planets around main-sequence stars - I. Sky maps for hot Jupiters

摘要

Context. The findings of more than 350extrasolarplanets, most of them nontransiting Hot Jupiters, have revealedcorrelations between the metallicity of the main-sequence(MS)host stars and planetary incidence. This connection can be used tocalculate the planet formation probability around other stars, not yetknown to have planetary companions. Numerous wide-field surveys haverecently been initiated, aiming at the transit detection of extrasolarplanets in front of their host stars. Depending on instrumentalproperties and the planetary distribution probability, the promisingtransit locations on the celestial plane will differ among thesesurveys. Aims. We want to locate the promising spots for transit surveyson the celestial plane and strive for absolute values of the expectednumber of transits in general. Our study will also clarify the impactof instrumental properties such as pixel size, field ofview(FOV), and magnitude range on the detection probability. Methods. We used data of the Tycho catalog for 1million objects to locate all the stars with on the celestial plane. We took several empirical relations between theparameters listed in the Tycho catalog, such as distance to Earth, ,and (B-V),and those parameters needed to account for the probability of a star tohost an observable, transiting exoplanet. The empirical relationsbetween stellar metallicity and planet occurrence combined withgeometrical considerations were used to yield transit probabilities forthe MSstars in the Tycho catalog. Magnitude variations in the FOVwere simulated to test whether this fluctuations would be detected byBEST, XO, SuperWASP and HATNet. Results. We present a sky map of the expected number of HotJupiter transit events on the basis of the Tycho catalog. Conditionedby the accumulation of stars towards the galactic plane, the zone ofthe highest number of transits follows the same trace, interrupted byspots of very low and high expectation values. The comparison betweenthe considered transit surveys yields significantly differing maps ofthe expected transit detections. While BEST provides an unpromisingmap, those for XO, SuperWASP, and HATNet show FsOV with up to10and more expected detections. The sky-integrated magnitude distributionpredicts 20Hot Jupiter transits with orbital periods between1.5d and 50d and ,of which two are currently known. In total, we expect 3412HotJupiter transits to occur in front of MS stars within the givenmagnitude range. The most promising observing site on Earth is atlatitude =-1. Key words: planetary systems - occultations - solar neighborhood- Galaxy: abundances - instrumentation: miscellaneous - methods:observational