Doyle, Laurance R.; Dunham, Edward T.; Deeg, H. J.; Blue, J. Ellen; Jenkins, Jon M.
Bibliographical reference
Journal of Geophysical Research, Volume 101, Issue E6, CiteID null
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1996
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Description
The detection of terrestrial-sized extrasolar planets from the ground
has been thought to be virtually impossible due to atmospheric
scintillation limits. However, we show that this is not the case for
specially selected (but nevertheless main sequence) stars, namely small
eclipsing binaries. For the smallest of these systems, CM Draconis,
several months to a few years of photometric observations with 1-m-class
telescopes will be sufficient to detect the transits of any short-period
planets of sizes ≥1.5 Earth radii (RE), using
cross-correlation analysis with moderately good photometry. Somewhat
larger telescopes will be needed to extend this detectability to
terrestrial planets in larger eclipsing binary systems. (We arbitrarily
define “terrestrial planets” herein as those whose disc
areas are closer to that of Earth's than Neptune's i.e., less than about
2.78 RE.) As a “spin-off” of such observations,
we will also be able to detect the presence of Jovian-mass planets
without transits using the timing of the eclipse minima. Eclipse minima
will drift in time as the binary system is offset by a sufficiently
massive planet (i.e., one Jupiter mass) about the binary/giant-planet
barycenter, causing a periodic variation in the light travel time to the
observer. We present here an outline of present observations taking
place at the University of California Lick Observatory using the
Crossley 0.9-m telescope in collaboration with other observatories (in
South Korea, Crete, France, Canary Islands, and New York) to detect or
constrain the existence of terrestrial planets around main sequence
eclipsing binary star systems, starting with CM Draconis. We demonstrate
the applicability of photometric data to the general detection of gas
giant planets via eclipse minima timings in many other small-mass
eclipsing binary systems as well.