constants¶
Nominal values of solar and planetary constants in SI units from IAU Resolution B3 1 plus related constants
Masses in SI units are derived using the 2014 CODATA value for the Newtonian constant, \(G=6.67408\times 10^{-11}\,m^3\,kg^{-1}\,s^{-2}\).
The following conversion constants are defined.
Solar conversion constants¶
R_SunN - solar radius
S_SunN - total solar irradiance
L_SunN - luminosity
Teff_SunN - solar effective temperature
GM_SunN - solar mass parameter
M_SunN - solar mass derived from GM_SunN and G_2014
V_SunN - solar volume = (4.pi.R_SunN**3/3)
Planetary conversion constants¶
R_eEarthN - equatorial radius of the Earth
R_pEarthN - polar radius of the Earth
R_eJupN - equatorial radius of Jupiter
R_pJupN - polar radius of Jupiter
GM_EarthN - terrestrial mass parameter
GM_JupN - jovian mass parameter
M_EarthN - mass of the Earth from GM_EarthN and G_2014
M_JupN - mass of Jupiter from GM_JupN and G_2014
V_EarthN - volume of the Earth (4.pi.R_eEarthN^2.R_pEarthN/3)
V_JupN - volume of Jupiter (4.pi.R_eJupN^2.R_pJupN/3)
R_EarthN - volume-average radius of the Earth (3.V_EarthN/4.pi)^(1/3)
R_JupN - volume-average radius of Jupiter (3.V_JupN/4.pi)^(1/3)
Example¶
Calculate the density relative to Jupiter for a planet 1/10 the radius of the Sun with a mass 1/1000 of a solar mass. Note that we use the volume-average radius for Jupiter in this case:
>>> from pycheops.constants import M_SunN, R_SunN, M_JupN, R_JupN
>>> M_planet_Jup = M_SunN/1000 / M_JupN
>>> R_planet_Jup = R_SunN/10 / R_JupN
>>> rho_planet_Jup = M_planet_Jup / (R_planet_Jup**3)
>>> print ("Planet mass = {:.3f} M_Jup".format(M_planet_Jup))
>>> print ("Planet radius = {:.3f} R_Jup".format(R_planet_Jup))
>>> print ("Planet density = {:.3f} rho_Jup".format(rho_planet_Jup))
Planet mass = 1.048 M_Jup
Planet radius = 0.995 R_Jup
Planet density = 1.063 rho_Jup
References