2012ApJ...744..175X

We present Submillimeter Array (SMA) observations of the massive star-forming region IRAS 20126+4104 in the millimeter continuum and in several molecular line transitions. With the SMA data, we have detected nine molecular transitions, including deuterated hydrogen cyanide, CH₃OH, H₂CO, and HC₃ N molecules, and imaged each molecular line. From the 1.3 mm continuum emission a compact millimeter source is revealed, which is also associated with H₂O, OH, and CH₃ OH masers. Using a rotation temperature diagram, we derive that the rotational temperature and the column density of CH₃ OH are 200 K and 3.7 x10¹⁷/cm2, respectively. The calculated results and analysis further indicate that a hot core coincides with IRAS 20126+4104. The position-velocity diagrams of H₂ CO (3_0.3 - 2_0.2) and HC₃N (25-24) clearly present Keplerian rotation. Moreover, H₂ CO (3_0.3 - 2_0.2) is found to trace the disk rotation for the first time.