Kinematic Distance Calculation Tool

Back to Trey's Homepage | Kinematic Distance Tool Homepage

This tool calculates kinematic distances in the same manner used in Wenger et al. (2018). It is useful for quickly calculating the kinematic distance of a single object, but users who wish to perform this calculation on many objects or wish to change the default parameters of the calculation should download the code on Github and run it locally. If you use this tool or code in published work, please reference the paper, the ASCL entry, and the DOI: zenodo.1166001.

Given a Galactic longitude, latitude, LSR velocity, and LSR velocity uncertainty, this tool calculates the kinematic distance using three different methods:

For more details about the calculation (including limitations), please see Wenger et al. (2018). If you have questions or suggestions, please contact me.

Galactic longitude (degrees)
Note: Kinematic distances are inaccurate in the direction of the Galactic center and Galactic anti-center
Galactic latitude (degrees)
Note: These distances assume the target has latitude 0 degrees. This latitude is only used to correct the LSR velocity with the updated solar motion parameters.
LSR velocity (km/s)
LSR velocity uncertainty (km/s)

Below is the output from your job:

Input longitude: 340.0 deg
Input latitude: 0.0 deg
Input velocity: -35.0 km/s
Input velocity error: 5.0 km/s

Method A: Traditional kinematic distance, Brand & Blitz (1993) rotation curve, IAU-defined solar motion parameters.
Galactocentric radius: 5.80 kpc
Near kinematic distance: 2.97 kpc
Far kinematic distance: 13.01 kpc
Tangent point kinematic distance: 7.99 kpc
Galactocentric radius of tangent point 2.91 kpc
LSR velocity of tangent point: -139.0 km/s

Using Reid et al. (2014) solar motion parameters to correct LSR velocity.
Corrected LSR velocity: -34.47 km/s
Corrected LSR velocity error: 5.74 km/s

Method B: Traditional kinematic distance, Reid et al. (2014) rotation curve and updated solar motion parameters.
Galactocentric radius: 5.80 kpc
Near kinematic distance: 2.78 kpc
Far kinematic distance: 12.89 kpc
Tangent point kinematic distance: 7.84 kpc
Galactocentric radius of tangent point 2.85 kpc
LSR velocity of tangent point: -117.9 km/s

Warning, cannot import Cython kernel functions, pure python functions will be used instead
convert-im6.q16: profile 'icc': 'RGB ': RGB color space not permitted on grayscale PNG `jobs/1957/340.0glong_-34.46921216535963velo.png' @ warning/png.c/MagickPNGWarningHandler/1667.
Method C: Monte Carlo kinematic distance, Reid et al. (2014) rotation curve and updated solar motion parameters.
The errors (+XX / -YY) represent the 68.3% confidence interval.
Galactocentric radius: 5.75 (+0.39 / -0.34) kpc
Near kinematic distance: 2.79 (+0.44 / -0.40) kpc
Far kinematic distance: 12.89 (+0.44 / -0.51) kpc
Tangent point kinematic distance: 7.85 (+0.11 / -0.18) kpc
Galactocentric radius of tangent point 2.86 (+0.04 / -0.07) kpc
LSR velocity of tangent point: -121.2 (+16.8 / -8.9) km/s

Done!

Method C Probability Distribution Functions:

PDFs
Download as PDF

These figures are the probability distribution functions of the Monte Carlo kinematic distances: Galactocentric radius (R), Galactocentric radius of the tangent point (Rtan), near kinematic distance (dnear) far kinematic distance (dfar), and tangent point kinematic distance (dtan). The data are the distributions of the Monte Carlo samples, the solid curve is the kernel density estimation (KDE) using the linear combination technique from Jones (1993), the dashed vertical line is the Method B kinematic distance, the solid vertical line is the peak of the KDE and the Method C kinematic distance, and the gray region is the 68.3% confidence interval (the errors on the Method C kinematic distance).