CO J=2-1 and CO J=3-2 observations toward the high-mass protostellar candidate IRAS 20188+3928

TL;DR

This study presents observations of CO lines toward IRAS 20188+3928, revealing bipolar outflow features, associated masers, and physical conditions of the gas, contributing to understanding high-mass star formation processes.

Contribution

First detailed CO J=2-1 and J=3-2 observations of IRAS 20188+3928, identifying outflow dynamics and physical parameters of the region.

Findings

Detected bipolar outflow in CO lines.

H2O maser not associated with outflow.

Derived gas densities and temperatures for outflow lobes.

Abstract

We have carried out 12CO J=2-1 and 12CO J=3-2 observations toward the high-mass protostellar candidate IRAS 20188+3928. Compared with previous observations, the 12CO J=2-1 and 12CO J=3-2 lines both have asymmetric profiles with an absorption dip. The velocity of the absorption dip is 1.0 km/s. The spectral shape may be caused by rotation. The velocity-integrated intensity map and position-velocity diagram of the 12CO 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 H2O maser. The H2O maser has the velocity of 1.1 km/s. Compared with the components of the outflow, we find that the H2O 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}).