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2 Acta Astronomica

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Toward the Detection of Transiting Hot Earths and Hot Neptunes in Open Clusters

Pepper J., Gaudi B. S.

Acta Astronomica

2006

Vol. 56, No. 2

183--197

Radial velocity searches for extrasolar planets have recently detected several very low mass (7-20 Msolar) planets in close orbits with periods ≤10 days. We consider the prospects for detecting the analogs of these planets in Galactic open clusters via transits. We outline the requirements for constructing a transit survey that would allow one to probe such "Hot Earths" and "Hot Neptunes." Specifically, we present a simple criterion for detection that defines the minimum aperture required to detect planets of a given radius in a cluster at a given distance. Adopting photometric precisions that have been demonstrated in state-of-the-art variability surveys, we then predict the number of planets one could potentially detect with ambitious transit surveys toward several open clusters. Dedicated surveys lasting more than 20 nights with Pan-STARRS toward the Hyades and Praesepe could detect a handful of Hot Earths, if the majority of stars host such planets. Similar surveys with larger aperture telescopes (e.g., CFHT, MMT), toward M 67, M 35, M 50, and M 37 could detect Hot Neptunes, provided that their frequency is ≥1%. The majority of planets will be detected around M dwarfs; detecting Hot Neptunes around such primaries requires photometric precisions of ≈1%, whereas Hot Earths require ≈0.1%. We discuss potential hurdles in detecting and confirming small planets in ground-based surveys, including correlated noise, false positives, and intrinsic stellar variability.

Using All-Sky Surveys to Find Planetary Transits

Pepper J., Gould A., DePoy D. L.

Acta Astronomica

2003

Vol. 56, No. 3

213--228

Transits of bright stars offer a unique opportunity to study detailed properties of extrasolar planets that cannot be determined through radial-velocity observations. We propose a new technique to find such systems using all-sky small-aperture transit surveys. We derive a general formula for the number of stars that can be probed for such systems as a function of the characteristics of the star, the planet, and the survey. We use this formula to derive the optimal telescope design for finding transits of bright stars: a 2 inch "telescope" with a 4k×4k camera.