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ASTROMETRY OF IRAS 22555+6213 WITH VERA: A 3-DIMENSIONAL VIEW OF SOURCES ALONG THE SAME LINE OF SIGHT

  • CHIBUEZE, JAMES O. (East Asian ALMA Regional Center, National Astronomical Observatory of Japan) ;
  • SAKANOUE, HIROFUMI (Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University) ;
  • OMODAKA, TOSHIHIRO (Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University) ;
  • HANDA, TOSHIHIRO (Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University) ;
  • NAGAYAMA, TAKUMI (Mizusawa VLBI Observatory, National Astronomical Observatory of Japan) ;
  • KAMEZAKI, TATSUYA (Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University) ;
  • BURNS, ROSS (Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University)
  • Received : 2014.11.30
  • Accepted : 2015.06.30
  • Published : 2015.09.30

Abstract

We report results of the measurement of the trigonometric parallax of an $H_2O$ maser source in IRAS 22555+6213 with the VLBI Exploration of Radio Astrometry (VERA). The annual parallax was determined to be $0.278{\pm}0.019$ mas, corresponding to a distance of $3.66^{+0.30}_{-0.26}kpc$. Our results confirm that IRAS 22555+6213 is located in the Perseus arm. We computed the peculiar motion of IRAS 22555+6213 to be ($U_{src}$, $V_{src}$, $W_{src}$) = ($0{\pm}1$, $-32{\pm}1$, $9{\pm}1$) $km\;s^{-1}$, where $U_{src}$, $V_{src}$, and $W_{src}$ are directed toward the Galactic center, in the direction of Galactic rotation and toward the Galactic north pole, respectively. IRAS 22555+6213, NGC7538 and Cepheus A lie along the same line of sight, and are within $2^{\circ}$ on the sky. Their parallax distances, with which we derived their absolute position in the Milky Way, show that IRAS 22555+6213 and NGC7538 are associated with the Perseus arm, while Cepheus A is located in the Local arm. We compared the kinematic distances of IRAS 22555+6213 derived with flat and non-flat rotation curve with its parallax distance and found the kinematic distance derived from the non-flat rotation assumption ($-32km\;s^{-1}$ lag) to be consistent with the parallax distance.

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References

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