Astrophysical parameters

[Constant]LAL_REARTH_SI [Constant]LAL_AWGS84_SI [Constant]LAL_BWGS84_SI [Constant]LAL_MEARTH_SI [Constant]LAL_IEARTH [Constant]LAL_EEARTH [Constant]LAL_RSUN_SI [Constant]LAL_MSUN_SI [Constant]LAL_MRSUN_SI [Constant]LAL_MTSUN_SI [Constant]LAL_LSUN_SI [Constant]LAL_AU_SI [Constant]LAL_PC_SI [Constant]LAL_YRTROP_SI [Constant]LAL_YRSID_SI [Constant]LAL_DAYSID_SI [Constant]LAL_LYR_SI [Constant]LAL_H0_SI [Constant]LAL_H0FAC_SI [Constant]LAL_RHOC_SI [Constant]LAL_RHOCFAC_SI [Constant]LAL_TCBR_SI [Constant]LAL_VCBR_SI [Constant]LAL_RHOCBR_SI [Constant]LAL_NCBR_SI [Constant]LAL_SCBR_SI

The following parameters are derived from measured properties of the Earth and Sun. The values are taken from [1], except for the obliquity of the ecliptic plane and the eccentricity of Earth's orbit, which are taken from [2]. All values are given in the SI units shown.

Name	Value	Description
LAL_REARTH_SI	$6.378140\times10^6 \mathrm{m}$	Earth equatorial radius
LAL_AWGS84_SI	$6.378137\times10^6 \mathrm{m}$	Semimajor axis of WGS-84 Reference Ellipsoid
LAL_BWGS84_SI	$6.356752314\times10^6 \mathrm{m}$	Semiminor axis of WGS-84 Reference Ellipsoid
LAL_MEARTH_SI	$5.97370\times10^{24} \mathrm{kg}$	Earth mass
LAL_IEARTH	$0.409092804 \mathrm{rad}$	Obliquity of the ecliptic (2000)
LAL_EEARTH	0.0167	Earth orbital eccentricity
LAL_RSUN_SI	$6.960\times10^8 \mathrm{m}$	Solar equatorial radius
LAL_MSUN_SI	$1.98892\times10^{30} \mathrm{kg}$	Solar mass
LAL_MRSUN_SI	$1.47662504\times10^3 \mathrm{m}$	Geometrized solar mass (length)
LAL_MTSUN_SI	$4.92549095\times10^{-6} \mathrm{s}$	Geometrized solar mass (time)
LAL_LSUN_SI	$3.846\times10^{26} \mathrm{W}$	Solar luminosity
LAL_AU_SI	$1.4959787066\times10^{11} \mathrm{m}$	Astronomical unit
LAL_PC_SI	$3.0856775807\times10^{16} \mathrm{m}$	Parsec
LAL_YRTROP_SI	$31 556 925.2 \mathrm{s}$	Tropical year (1994)
LAL_YRSID_SI	$31 558 149.8 \mathrm{s}$	Sidereal year (1994)
LAL_DAYSID_SI	$86 164.09053 \mathrm{s}$	Mean sidereal day
LAL_LYR_SI	$9.46052817\times10^{15} \mathrm{m}$	$c\times$tropical year (1994)

The following cosmological parameters are derived from measurements of the Hubble expansion rate and of the cosmic background radiation (CBR). Data are taken from [1]. In what follows, the normalized Hubble constant $h_0$ is equal to the actual Hubble constant $H_0$ divided by $\langle H \rangle=100 \mathrm{km} \mathrm{s}^{-1}\mathrm{Mpc}^{-1}$. Thus the Hubble constant can be written as:

$$H_0 = \langle H \rangle h_0 \; .$$

Similarly, the critical energy density $\rho_c$ required for spatial flatness is given by:

$$\rho_c = \langle\rho\rangle h_0^2 \; .$$

Current estimates give $h_0$ a value of around 0.65, which is what is assumed below. All values are in the SI units shown.

Name	Value	Description
LAL_H0_SI	$2\times10^{-18} \mathrm{s}^{-1}$	Approx. Hubble constant $H_0$
LAL_H0FAC_SI	$3.2407792903\times10^{-18} \mathrm{s}^{-1}$	$H_0/h_0$
LAL_RHOC_SI	$7\times10^{-10} \mathrm{J} \mathrm{m}^{-3}$	Approx. critical energy density $\rho_c$
LAL_RHOCFAC_SI	$1.68860\times10^{-9} \mathrm{J} \mathrm{m}^{-3}$	$\rho_c/h_0^2$
LAL_TCBR_SI	$2.726 \mathrm{K}$	CBR temperature
LAL_VCBR_SI	$3.695\times10^5 \mathrm{m} \mathrm{s}^{-1}$	Solar velocity with respect to CBR
LAL_RHOCBR_SI	$4.177\times10^{-14} \mathrm{J} \mathrm{m}^{-3}$	Energy density of CBR
LAL_NCBR_SI	$4.109\times10^8 \mathrm{m}^{-3}$	Number density of CBR photons
LAL_SCBR_SI	$3.993\times10^{-14} \mathrm{J} \mathrm{K}^{-1} \mathrm{m}^{-3}$	Entropy density of CBR

Author: Creighton, T. D.
$Id: LALConstants.h,v 1.9 2001/08/21 04:19:52 jolien Exp $