Units

The following table list the units available for use in the configuration files. All units are consistent with the scipy.constants values. Radius values are the nominal equatorial values adopted in [Prsa2016]. Mass values are consistent with the nominal mass parameter from [Prsa2016] and a gravitational constant of \(G=6.67408\times10^{-11}\) m3 kg-1 s-2 (same value used in scipy.constants and astropy.constants).

Quantity

Unit name

CGS Value

Description

Reference

Length

A

1.0e-08

Angstrom

nm

1.0e-07

Nanometer

um

1.0e-04

Micron

mm

1.0e-01

Millimeter

cm

1.0

Centimeter

m

1.0e+02

Meter (MKS unit)

km

1.0e+05

Kilometer

au

1.49597e+13

Astronomical unit

pc

3.08568e+18

Parsec

rearth

6.3781e+08

Earth radius

[Prsa2016]

rjup

7.1492e+09

Jupiter mean radius

[Prsa2016]

rsun

6.957e+10

Sun radius

[Prsa2016]

Mass

me

9.10938e-28

Electron mass

amu

1.66054e-24

Unified atomic mass

gram

1.0

Gram

kg

1.0e3

Kilogram (MKS unit)

mearth

5.97236e+27

Earth mass

[Prsa2016]

mjup

1.898187e+30

Jupiter mass

[Prsa2016]

msun

1.988475e+33

Sun mass

[Prsa2016]

Pressure

barye

1.0

Barye

mbar

1000.0

Millibar

pascal

1.0e+05

Pascal (MKS unit)

bar

1.0e+06

Bar

atm

1.01e+06

Atmosphere

Time

sec

1.0

Second

min

60.0

Minute

hour

3600.0

Hour

day

86400.0

Day

Unitless

none

1.0

None

percent

1.0e-2

Percent

ppt

1.0e-3

Parts per thousand

ppm

1.0e-6

Parts per million

Number density

amagat

2.6867811e+19

Loschmidt constant

The user can access these units and other constants during a Python interactive seesion via the pyratbay.constants sub-module, for example:

import pyratbay.constants as pc

print('1e-5 bar is {:.1f} barye'.format(1e-5*pc.bar))
1e-5 bar is 10.0 barye