Symbol
Meaning
Typical unit
Introducing
equation
N A
Avogadro number
Unitless
2.90
N d
Dust column density
[molecule m
À2
]
4.2
n dau
Number density of the daughter product
5.4
n e
Electron density
[m
À3
]
3.39
n g,d
Local gas (dust) density
[molecule m
À3
],
[kg m
À3
]
2.98, 2.136,
4.1
n gp
Local parent density
[m
À3
]
3.111
n h
Power-law exponent describing the drop in
brightness with r h
Unitless
1.3
n i, n n
Ion (neutral) density
[m
À3
]
3.116
N m
Number of monomers in a particle structure Unitless
4.41
n N
Local density of the neutral (similar to n g )
[m
À3
]
3.39
N p
Number of particles per unit volume
#
2.116
n par
Number density of a parent molecule
[molecule m
À3
]
5.4
N s
Column density from the Sun to a point in
the coma sunward of the nucleus
[m
À2
]
5.7
OPR
Ratio of ortho-H 2 to para-H 2
3.127
p
Geometric albedo
Unitless
2.1
P
Orbital period
[s]
1
P
Position in space
[m]
2.30
Ƥ
Degree of polarization
Unitless
4.11
p(α)
Phase function for single scattering at a
phase angle, α by atoms or molecules
3.118
p a,b, T a,b
Pressure and temperature on either side of a
layer or tube
[Pa]
3.104
P crit
Critical period either of an oblate spheroid
for the splitting of the nucleus or of the
balance between centrifugal and gravitational acceleration
[s]
2.36, 2.57
p d
Geometric albedo of dust particles
Unitless
4.35
p dyn
Dynamic pressure
[Pa]
5.1
p L
Semi-latus rectum of an orbit
[AU]
1.23
P l
Population in a quantized energy level
3.36
Ƥ L, Ƥ C
Degree of linear (circular) polarization
Unitless
4.13, 4.14
p mag
Magnetic pressure
[Pa]
5.2
p s
Equilibrium vapour pressure
[Pa]
2.89
p s
Albedo normalized to geometric albedo in
backscattering geometry but follows the
behaviour of the scattering function
Unitless
4.36
p STP
Pressure under STP conditions
[Pa]
3.31
q
Periapsis distance for parabolic motion
[m]
1.12
q
Vectorial heat flux
[W m
À2
]
3.65
q c
Particle charge
[C]
2.131
(continued)
Symbols Used
xxix
Meaning
Typical unit
Introducing
equation
N A
Avogadro number
Unitless
2.90
N d
Dust column density
[molecule m
À2
]
4.2
n dau
Number density of the daughter product
5.4
n e
Electron density
[m
À3
]
3.39
n g,d
Local gas (dust) density
[molecule m
À3
],
[kg m
À3
]
2.98, 2.136,
4.1
n gp
Local parent density
[m
À3
]
3.111
n h
Power-law exponent describing the drop in
brightness with r h
Unitless
1.3
n i, n n
Ion (neutral) density
[m
À3
]
3.116
N m
Number of monomers in a particle structure Unitless
4.41
n N
Local density of the neutral (similar to n g )
[m
À3
]
3.39
N p
Number of particles per unit volume
#
2.116
n par
Number density of a parent molecule
[molecule m
À3
]
5.4
N s
Column density from the Sun to a point in
the coma sunward of the nucleus
[m
À2
]
5.7
OPR
Ratio of ortho-H 2 to para-H 2
3.127
p
Geometric albedo
Unitless
2.1
P
Orbital period
[s]
1
P
Position in space
[m]
2.30
Ƥ
Degree of polarization
Unitless
4.11
p(α)
Phase function for single scattering at a
phase angle, α by atoms or molecules
3.118
p a,b, T a,b
Pressure and temperature on either side of a
layer or tube
[Pa]
3.104
P crit
Critical period either of an oblate spheroid
for the splitting of the nucleus or of the
balance between centrifugal and gravitational acceleration
[s]
2.36, 2.57
p d
Geometric albedo of dust particles
Unitless
4.35
p dyn
Dynamic pressure
[Pa]
5.1
p L
Semi-latus rectum of an orbit
[AU]
1.23
P l
Population in a quantized energy level
3.36
Ƥ L, Ƥ C
Degree of linear (circular) polarization
Unitless
4.13, 4.14
p mag
Magnetic pressure
[Pa]
5.2
p s
Equilibrium vapour pressure
[Pa]
2.89
p s
Albedo normalized to geometric albedo in
backscattering geometry but follows the
behaviour of the scattering function
Unitless
4.36
p STP
Pressure under STP conditions
[Pa]
3.31
q
Periapsis distance for parabolic motion
[m]
1.12
q
Vectorial heat flux
[W m
À2
]
3.65
q c
Particle charge
[C]
2.131
(continued)
Symbols Used
xxix