12COJ=2-1and12COJ=3-2observationstowardthehigh-massprotostellarcandidateIRAS20188+3928

We have carried out observations of 12 CO J=2-1 and 12 CO J=3-2 toward the high-mass protostellar candidate IRAS 20188+3928.Compared with previous observations,the 12 CO J=2-1 and 12 CO J=3-2 lines both have asymmetric profiles with an absorption dip.The velocity of the absorption dip is ～ 1.0 km s 1.The spectral shape may be caused by rotation.The velocity-integrated intensity map and position-velocity diagram of the 12 CO J=2-1 line present an obvious bipolar component,further verifying that this region has an outflow motion.This region is also associated with an HII region,an IRAS source,and an H 2 O maser.The H 2 O maser has the velocity of 1.1 km s 1.Compared with the components of the outflow,we find that the H 2 O maser is not associated with the outflow.Using the large velocity gradient model,we concluded that possible averaged gas densities of the blueshifted lobe and redshifted lobe are 1.0×10 5 cm 3 and 2.0×10 4 cm 3,while kinetic temperatures are 26.9 K and 52.9 K,respectively.Additionally,the outflow has a higher integrated intensity ratio (I CO J =3 2 /I CO J =2 1).