Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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VLA AMMONIA LINE OBSERVATIONS OF THE YOUNG STELLAR OBJECT IRAS 19550+3248

  • LEE Ho-GYU (Astronomy Program, SEES, Seoul National University) ;
  • KOO BON-CHUL (Astronomy Program, SEES, Seoul National University) ;
  • PARK YONG-SUN (Astronomy Program, SEES, Seoul National University) ;
  • HO PAUL T. P. (Harvard-Smithsonian Center for Astrophysics)
  • Published : 2002.06.01
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Abstract

We present the results of VLA $NH_3$ (1,1) and (2,2) line observations of the young-stellar object (YSO) IRAS 19550+3248. The integrated intensity map of the $NH_3$ (1,1) line shows that there are two ammonia cores in this region; core A which is associated with the YSO, and core B which is diffuse and located at the northeast of core A. Core A is compact and elongated along the east-west direction (0.07 pc$\times$0.05 pc) roughly perpendicular to the molecular outflow axis. Core B is diffuse and extended (0.18 pc$\times$0.07 pc). $NH_3$ (2,2) line is detected only toward core A, which indicates that it is hotter (~ 15 K), presumably due to the heating by the YSO. The $NH_3$ (1,1) line toward core A is wide (${\Delta}v{\ge} 3 km s^{-l}$) and appears to have an anomalous intensity ratio of the inner satellite hyperfine lines. The large line width may be attributed to the embedded YSO, but the hyperfine anomaly is difficult to explain. We compare the results of $NH_3$ observations with those of previous CS observations and find that the CS emission is detected only toward core A and is much more extended than the $NH_3$ emission.

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References

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