Kinematic distances of star-forming regions

Method

A), the traditional method using the Reid+ (2014, J/ApJ/783/130) rotation curve and updated solar motion parameters (

Method

B), and a Monte Carlo technique (

Method

C).

Methods

B and C produce kinematic distances closest to the parallax distances, with median differences of 13% (0.43kpc) and 17% (0.42kpc), respectively. Except in the vicinity of the tangent point, the kinematic distance uncertainties derived by

Method

C are smaller than those of

Methods

A and B. In a large region of the Galaxy, the

Method

C kinematic distances constrain both the distances and the Galactocentric positions of HMSFRs more accurately than parallax distances. Beyond the tangent point along l=30{deg}, for example, the

Method

C kinematic distance uncertainties reach a minimum of 10% of the parallax distance uncertainty at a distance of 14kpc. We develop a prescription for deriving and applying the

Method

C kinematic distances and distance uncertainties. The code to generate the

Method

C kinematic distances is publicly available and may be utilized through an online tool.