Symbol
Meaning
Typical unit
Introducing
equation
λ ce
Mean free path for electrons
[m]
5.36
λ M
Photometric longitude
[rad]
2.77
λ max
Maximum pore size
[m]
2.119
λ MFP
Mean free path
[m]
3.42
λ ref
Reference wavelength
[m]
2.86
λ s,th
Photoionization threshold for species s
5.6
μ, GM
(GM ⨀ )
Geopotential of a star (the Sun)
[m
3 s
À2
]
1
μ
Cosine of the emission angle, e
Unitless
2.65
μ 0
Cosine of the incidence angle, i
Unitless
2.60
μ 0
Permeability of free space
5.2
μ imp, v imp
Coefficients in the impact cratering
equations
2.129
μ r
Reduced mass of the nucleus and the
projectile
7.2
μ rig
Rigidity
[Pa]
2.54
μ v
Coefficient of dynamic viscosity
3.63, 4.94
ϑ
Frequency
[Hz]
2.8
ν 0
Rest frequency of emission line
[Hz]
3.23
ν k
Kinematic viscosity
3.62
ξ
Asymmetry parameter
Unitless
2.71
ξ P
Light penetration scale length
[m]
2.114
ξ T
Tortuosity
Unitless
3.103
ρ
Radial size of a circular aperture on the sky [km]
4.58
ρ 1
Upstream solar wind mass density
[kg m
À3
]
5.28
ρ a
Dust particle bulk density
[kg m
À3
]
4.66
ρ C
Reflectance coefficient
Unitless
2.60
ρ dl
Reflectance of a large dust particle
Unitless
4.109
ρ F
Reflectance factor, REFF
Unitless
2.62
ρ g
Local gas mass density
[kg m
À3
]
2.132
ρ N, ρ d
Bulk mass density of a body (dust grains)
[kg m
À3
]
2.128
ρ ref
Reflectance factor at a reference wavelength Unitless
2.85
ρ s
Particle mass density
[kg m
À3
]
2.132
ρ s-d
Reflectance of a single particle at a specific
phase angle
Unitless
4.110
ρ sw
Mass density of the solar wind
5.1
ρ V
Density of a volume element dV
[kg m
À3
]
2.30
σ
Stefan–Boltzmann constant
[W m
À2 K
À4
]
2.7
σ abs,sca,ext
Absorption, scattering, extinction cross
section
[m
2
]
3.12
σ col
Collision cross section
[m
2
]
3.39
σ cx,H
Proton–hydrogen atom charge exchange
cross section
[m
2
]
5.9
(continued)
Symbols Used
xxxv
Meaning
Typical unit
Introducing
equation
λ ce
Mean free path for electrons
[m]
5.36
λ M
Photometric longitude
[rad]
2.77
λ max
Maximum pore size
[m]
2.119
λ MFP
Mean free path
[m]
3.42
λ ref
Reference wavelength
[m]
2.86
λ s,th
Photoionization threshold for species s
5.6
μ, GM
(GM ⨀ )
Geopotential of a star (the Sun)
[m
3 s
À2
]
1
μ
Cosine of the emission angle, e
Unitless
2.65
μ 0
Cosine of the incidence angle, i
Unitless
2.60
μ 0
Permeability of free space
5.2
μ imp, v imp
Coefficients in the impact cratering
equations
2.129
μ r
Reduced mass of the nucleus and the
projectile
7.2
μ rig
Rigidity
[Pa]
2.54
μ v
Coefficient of dynamic viscosity
3.63, 4.94
ϑ
Frequency
[Hz]
2.8
ν 0
Rest frequency of emission line
[Hz]
3.23
ν k
Kinematic viscosity
3.62
ξ
Asymmetry parameter
Unitless
2.71
ξ P
Light penetration scale length
[m]
2.114
ξ T
Tortuosity
Unitless
3.103
ρ
Radial size of a circular aperture on the sky [km]
4.58
ρ 1
Upstream solar wind mass density
[kg m
À3
]
5.28
ρ a
Dust particle bulk density
[kg m
À3
]
4.66
ρ C
Reflectance coefficient
Unitless
2.60
ρ dl
Reflectance of a large dust particle
Unitless
4.109
ρ F
Reflectance factor, REFF
Unitless
2.62
ρ g
Local gas mass density
[kg m
À3
]
2.132
ρ N, ρ d
Bulk mass density of a body (dust grains)
[kg m
À3
]
2.128
ρ ref
Reflectance factor at a reference wavelength Unitless
2.85
ρ s
Particle mass density
[kg m
À3
]
2.132
ρ s-d
Reflectance of a single particle at a specific
phase angle
Unitless
4.110
ρ sw
Mass density of the solar wind
5.1
ρ V
Density of a volume element dV
[kg m
À3
]
2.30
σ
Stefan–Boltzmann constant
[W m
À2 K
À4
]
2.7
σ abs,sca,ext
Absorption, scattering, extinction cross
section
[m
2
]
3.12
σ col
Collision cross section
[m
2
]
3.39
σ cx,H
Proton–hydrogen atom charge exchange
cross section
[m
2
]
5.9
(continued)
Symbols Used
xxxv