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Detection and Characterization of Transiting Systems with Smaller Exoplanets

Published online by Cambridge University Press:  29 April 2014

Teruyuki Hirano
Affiliation:
Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan email: hirano@utap.phys.s.u-tokyo.ac.jp
Norio Narita
Affiliation:
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan
Akihiko Fukui
Affiliation:
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan
Roberto Sanchis-Ojeda
Affiliation:
Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Joshua N. Winn
Affiliation:
Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Yasushi Suto
Affiliation:
Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan email: hirano@utap.phys.s.u-tokyo.ac.jp
Atsushi Taruya
Affiliation:
Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan email: hirano@utap.phys.s.u-tokyo.ac.jp
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Abstract

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We present our effort to detect and characterize transiting systems with small exoplanets. First we present our on-going project to detect transiting exoplanets around late-type stars. As many authors point out, late-type stars can host potentially habitable rocky planets, whose transits are detectable with 2-meter class telescopes. We aim at detecting (small-sized) transiting exoplanets around M-type stars and are conducting a survey using the Okayama 1.88m telescope. We introduce our campaign at Okayama. Next we discuss the characterization of small-sized exoplanets. We focus on the measurement of the spin-orbit angle, the angle between the stellar spin axis and planetary orbital axis. The spin-orbit relations are of great importance in discussing planetary formations, evolutions, and migrations. To this point, the Rossiter-McLaughlin (RM) effect, an apparent radial velocity anomaly during a planetary transit, has been mainly investigated to measure the projected spin-orbit angles. However, as the size of the transiting planet becomes smaller, the detection of the RM effect becomes challenging because of the small RM signal. We have newly developed a technique to investigate spin-orbit relations for smaller planets by combining Kepler's ultra-precise photometry and spectroscopic measurements. We show that, contrary to planetary systems with close-in giant planets, most of the systems with small-sized planets (including Earth-sized ones) have smaller spin-orbit angles, which implies a different evolutional history of the planetary systems. We also discuss future prospects on the detection and characterization of smaller transiting exoplanets.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2014 

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