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SEARCH FOR DEBRIS DISKS BY AKARI AND IRSF

  • Takeuchi, Nami (Department of Physics, Graduate School of Science, Nagoya University) ;
  • Ishihara, Daisuke (Department of Physics, Graduate School of Science, Nagoya University) ;
  • Kaneda, Hidehiro (Department of Physics, Graduate School of Science, Nagoya University) ;
  • Oyabu, Shinki (Department of Physics, Graduate School of Science, Nagoya University) ;
  • Kobayashi, Hiroshi (Department of Physics, Graduate School of Science, Nagoya University) ;
  • Nagayama, Takahiro (Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University) ;
  • Onaka, Takashi (Department of Astronomy, School of Science, University of Tokyo) ;
  • Fujiwara, Hideaki (Subaru Telescope, National Astronomical Observatory of Japan)
  • Received : 2015.03.30
  • Accepted : 2016.10.20
  • Published : 2017.03.31

Abstract

Debris disks are important observational clues to understanding on-going planetary system formation. They are usually identified by significant mid-infrared excess on top of the photospheric emission of a central star on the basis of prediction from J-, H-, and Ks-band fluxes and the stellar model spectra. For bright stars, 2MASS near-infrared fluxes suffer large uncertainties due to the near-infrared camera saturation. Therefore we have performed follow-up observations with the IRSF 1.4 m near-infrared telescope located in South Africa to obtain accurate J-, H-, and Ks-band fluxes of the central stars. Among 754 main-sequence stars which are detected in the AKARI $18{\mu}m$ band, we have performed photometry for 325 stars with IRSF. As a result, we have successfully improved the flux accuracy of the central stars from 9.2 % to 0.5 % on average. Using this dataset, we have detected $18{\mu}m$ excess emission from 57 stars in our samples with a $3{\sigma}$ level. We find that some of them have high ratios of the excess to the photospheric emission even around very old stars, which cannot be explained by the current planet-formation theories.

Keywords

References

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