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The Korean Astronomical Society (한국천문학회)
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FLUX MONITORING OF 6.7 GHz METHANOL MASER TO SYSTEMATICALLY RESEARCH PERIODIC VARIATIONS USING THE HITACHI 32-m

  • SUGIYAMA, KOICHIRO (Center for Astronomy, Ibaraki University) ;
  • YONEKURA, YOSHINORI (Center for Astronomy, Ibaraki University) ;
  • MOTOGI, KAZUHITO (The Research Institute for Time Studies, Yamaguchi University) ;
  • SAITO, YU (College of Science, Ibaraki University) ;
  • FUJISAWA, KENTA (The Research Institute for Time Studies, Yamaguchi University) ;
  • ISHII, SHOTA (College of Science, Ibaraki University) ;
  • MOMOSE, MUNETAKE (College of Science, Ibaraki University) ;
  • HONMA, MAREKI (Mizusawa VLBI Observatory) ;
  • TAZAKI, FUMIE (Mizusawa VLBI Observatory) ;
  • TANAKA, KEI E.I. (Department of Astronomy, University of Florida, 211 Bryant Space Science Center) ;
  • HOSOKAWA, TAKASHI (Department of Physics and Research Center for the Early Universe, The University of Tokyo) ;
  • UCHIYAMA, MIZUHO (Institute of Astronomy, Graduate School of Science, The University of Tokyo) ;
  • INAYOSHI, KOHEI (Department of Astronomy, Columbia University)
  • Received : 2014.11.30
  • Accepted : 2015.06.30
  • Published : 2015.09.30
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Abstract

We have initiated single-dish monitoring observations of ~400 methanol maser sources at 6.7 GHz using the Hitachi 32-m radio telescope from December 2012 to systematically research periodic flux variations, which are observed in some methanol maser sources associated with high-mass (proto-)stars. In our monitoring, we have made daily monitoring, so that each source has been observed every nine days with an integration time of 5 min (typical $3{\sigma}$ detection sensitivities of 0.9 Jy). The monitoring observations help us statistically understand periodic flux variations with a period longer than 50 days. As an initial result, we present a new detection of periodic flux variations in the 6.7 GHz methanol maser source G 036.70+00.09. The period of the flux variations is ~53 days (~0.019 cycles $day^{-1}$), and seems to be stable over 9 cycles, at least until the middle of August 2014.

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References

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