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Chapter 13
Solar System Small Bodies
Richard P. Binzel, Martha S. Hanner, and Duncan I. Steel
13.1
13.1.1
13.1
Asteroids or Minor Planets . . . . . . . . . . . . . . . . 315
13.2
Comets . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
13.3
Zodiacal Light . . . . . . . . . . . . . . . . . . . . . . . 328
13.4
Infrared Zodiacal Emission . . . . . . . . . . . . . . . 331
13.5
Meteoroids and Interplanetary Dust . . . . . . . . . . . 333
ASTEROIDS OR MINOR PLANETS
Populations and Locations [1–3]
Number of minor planets having well-determined orbits, cataloged by permanent designations
(numbers) as of 1998, January 1: 8125.
Number of known minor planets having less well-determined orbits, cataloged by provisional
designations: > 25, 000.
Most are located in the Main-belt, between Mars and Jupiter.
Semimajor axis, range 2.06 to 3.28 AU, mean a = 2.68.
Mean orbital eccentricity: e = 0.142.
Mean orbital inclination: i = 7.92 deg.
Mean orbital period: 4.40 yr.
Number of main-belt asteroids larger than 100 km in diameter: 188, 50 km: 475.
Estimated population of main-belt asteroids larger than diameter D (in km):
N (> D) = 9.1 × 106 D −2.52 .
315
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S OLAR S YSTEM S MALL B ODIES
Near-Earth Asteroids (NEAs) are those approaching within 0.3 AU of the Earth’s orbit.
Atens: a < 1.0 AU, aphelion Q > 0.983 AU.
Number known as of 1998, January 1 = 27.
Apollos: a ≥ 1.0 AU, perihelion q ≤ 1.017 AU.
Number known as of 1998, January 1 = 213.
Amors: a > 1.0 AU, 1.017 < q ≤ 1.3 AU.
Number known as of 1998, January 1 = 207.
Aten and Apollo asteroids have orbits which cross the Earth’s orbit.
Orbits of many Amor asteroids can evolve to become Earth-crossing.
Estimated population of Earth-crossing asteroids having diameter:
> 1 km: 2100.
> 100 m: 320,000. (A size likely to survive passage through the terrestrial atmosphere.)
Typical collisional frequency (per object) with Earth, for an NEA having an Earth-crossing orbit:
Pi = 2.2 per 109 yr.
Mean collision velocity with Earth: Vc = 22.5 km/s.
Trojan asteroidsare located in the vicinities of the L 4 and L 5 Lagrange points of Jupiter.
Mean semimajor axis: a = 5.20 AU.
Mean eccentricity: e = 0.080.
Mean inclination: i = 15.9 deg.
Number known as of 1998, January 1: 413.
13.1.2
Magnitudes [4]
An asteroid’s absolute magnitude, H , is defined as its mean V magnitude (neglecting rotational and
aspect variations), if it were observed at a distance r = 1 AU from the Sun, = 1 AU from the Earth,
and a phase angle (Earth–object–Sun angle) α = 0. For other locations, an asteroid’s mean apparent
V magnitude can be expressed by
V = H (α) + 5 log r ,
where
H (α) = H − 2.5 log[(1 − G)
1 (α) + G
2 (α)].
G is called the slope parameter which accounts for an asteroid’s nonlinear change in brightness as
a function of phase angle only. 1 and 2 are described by
i = exp{−Ai [tan(α/2)] Bi };
A2 = 1.87,
A1 = 3.33,
B1 = 0.63,
i = 1, 2,
B2 = 1.22.
An asteroid’s diameter D (in km) can be estimated by
log D = 3.129 − 0.5 log p − 0.2H,
where p is its geometric albedo in the V passband.
An asteroid’s Bond albedo, A, is related to the geometric albedo by the phase integral, q, where
A = pq,
q = 0.290 + 0.684G;
0 ≤ G ≤ 1.
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13.1 A STEROIDS OR M INOR P LANETS / 317
13.1.3
Physical Properties [5]
Estimated total mass of the asteroids = 1.8 × 1024 g.
Estimated densities for most asteroids, 1.0 − 3.5 g cm−3 .
Possible compositions, typical albedos, slope parameters, and color indices for selected taxonomic
types of asteroids.
C-types: Carbonaceous chondrite, p = 0.05, G = 0.15, B − V = 0.70, U − B = 0.35.
S-types: Stony-Iron? Ordinary chondrite?, p = 0.19, G = 0.25, B − V = 0.85, U − B = 0.44.
M-types: Metal-rich?, p = 0.10, G = 0.20, B − V = 0.70, U − B = 0.25.
Typical rotation period, P ∼ 9 h. Observed range: 2 to > 1000 h.
Typical rotation light curve amplitude variation, M ∼ 0.2 mag. Observed range: 0 to > 1 mag.
Typical shape, modeled by a triaxial ellipsoid with axes a, b, c, where a > b > c:
√
a : b : c = 2 : 2 : 1.
Lowest energy rotation state occurs about the c-axis.
13.1.4
Data Tables
Tables 13.1 and 13.2 give the 100 largest and 147 of the nearest asteroids.
Table 13.1. The 100 largest asteroids [1].
No.
Name
1
2
4
10
511
704
52
15
87
16
24
31
65
3
324
107
624
532
451
48
19
29
121
423
13
45
94
88
7
702
Ceres
Pallas
Vesta
Hygiea
Davida
Interamnia
Europa
Eunomia
Sylvia
Psyche
Themis
Euphrosyne
Cybele
Juno
Bamberga
Camilla
Hektor
Herculina
Patientia
Doris
Fortuna
Amphitrite
Hermione
Diotima
Egeria
Eugenia
Aurora
Thisbe
Iris
Alauda
Year of
Discovery
D
(km)
a
e
i
P
(h)
M
(mag)
Type
p
H
G
U−B
B−V
1801
1802
1807
1849
1903
1910
1858
1851
1866
1852
1853
1854
1861
1804
1892
1868
1907
1904
1899
1857
1852
1854
1872
1896
1850
1857
1867
1866
1847
1910
913
523
501
429
337
333
312
272
271
264
249
248
245
244
242
237
233
231
230
225
221
219
217
217
215
214
212
210
203
202
2.77
2.77
2.36
3.14
3.18
3.06
3.10
2.64
3.49
2.92
3.13
3.14
3.44
2.67
2.68
3.48
5.18
2.77
3.06
3.11
2.44
2.55
3.44
3.08
2.58
2.72
3.16
2.77
2.39
3.19
0.078
0.234
0.091
0.120
0.178
0.148
0.100
0.185
0.083
0.134
0.134
0.228
0.104
0.258
0.341
0.084
0.024
0.176
0.071
0.069
0.158
0.072
0.143
0.034
0.086
0.083
0.082
0.164
0.230
0.029
10.6
34.8
7.1
3.8
15.9
17.3
7.4
11.8
10.9
3.1
0.8
26.3
3.5
13.0
11.1
9.9
18.2
16.4
15.2
6.5
1.6
6.1
7.6
11.2
16.5
6.6
8.0
5.2
5.5
20.6
9.075
7.811
5.342
18.4
5.13
8.727
5.631
6.083
5.183
4.196
8.38
5.531
6.07
7.21
29.43
4.84
6.921
9.405
9.727
11.89
7.445
5.39
6.1
4.622
7.045
5.699
7.22
6.042
7.139
8.36
0.04
0.03–0.16
0.12
0.09–0.18
0.06–0.25
0.03–0.11
0.09–0.10
0.4–0.56
0.30–0.62
0.03–0.42
0.10–0.14
0.09–0.13
0.04–0.12
0.14–0.22
0.07
0.32–0.52
0.1–1.1
0.08–0.18
0.05–0.10
0.35
0.22–0.35
0.01–0.15
0.03
0.06–0.18
0.12
0.08–0.41
0.12
0.08–0.21
0.04–0.29
0.07–0.10
G
B
V
C
C
F
CF
S
P
M
C
C
P
S
CP
C
D
S
CU
CG
G
S
C
C
G
FC
CP
CF
S
C
0.10
0.14
0.38
0.07
0.05
0.06
0.05
0.19
0.04
0.10
3.32
4.13
3.16
5.27
6.17
6.00
6.25
5.22
6.95
5.99
7.07
6.53
6.79
5.31
6.82
6.80
7.47
5.78
6.65
6.83
7.09
5.84
7.39
7.48
6.47
7.27
7.55
7.05
5.76
7.23
0.11
0.15
0.34
−0.04
0.02
0.02
0.00
0.20
0.28
0.22
0.10
0.15
0.15
0.30
0.10
−0.17
0.15
0.25
0.20
−0.05
0.10
0.21
0.15
0.68
−0.02
0.15
0.09
0.17
0.51
0.13
0.43
0.29
0.50
0.35
0.36
0.26
0.33
0.46
0.25
0.25
0.35
0.32
0.27
0.41
0.30
0.30
0.24
0.41
0.33
0.43
0.39
0.42
0.39
0.30
0.46
0.27
0.30
0.29
0.48
0.32
0.72
0.66
0.80
0.69
0.72
0.64
0.66
0.84
0.70
0.70
0.68
0.67
0.67
0.81
0.70
0.70
0.79
0.85
0.65
0.72
0.75
0.83
0.72
0.67
0.75
0.66
0.66
0.66
0.85
0.66
0.07
0.05
0.22
0.05
0.06
0.16
0.07
0.06
0.16
0.04
0.03
0.09
0.04
0.03
0.21
0.05
Sp.-V/AQuan/1999/10/10:09:50
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318 / 13
S OLAR S YSTEM S MALL B ODIES
Table 13.1. (Continued).
No.
375
372
128
6
154
76
130
22
259
776
41
2060
9
120
747
790
566
911
96
194
59
386
54
1437
334
444
241
409
185
11
139
354
804
165
39
89
173
488
536
85
150
238
145
49
117
168
14
51
106
20
1172
137
283
209
361
617
18
211
308
508
895
93
144
196
420
Name
Ursula
Palma
Nemesis
Hebe
Bertha
Freia
Elektra
Kalliope
Aletheia
Berbericia
Daphne
Chirona
Metis
Lachesis
Winchester
Pretoria
Stereoskopia
Agamemnon
Aegle
Prokne
Elpis
Siegena
Alexandra
Diomedes
Chicago
Gyptis
Germania
Aspasia
Eunike
Parthenope
Juewa
Eleonora
Hispania
Loreley
Laetitia
Julia
Ino
Kreusa
Merapi
Io
Nuwa
Hypatia
Adeona
Pales
Lomia
Sibylla
Irene
Nemausa
Dione
Massalia
Aneas
Meliboea
Emma
Dido
Bononia
Patroclus
Melpomene
Isolda
Polyxo
Princetonia
Helio
Minerva
Vibilia
Philomela
Bertholda
Year of
Discovery
D
(km)
a
e
i
1893
1893
1872
1847
1875
1862
1873
1852
1886
1914
1856
1977
1848
1872
1913
1912
1905
1919
1868
1879
1860
1894
1858
1937
1892
1899
1884
1895
1878
1850
1874
1893
1915
1876
1856
1866
1877
1902
1904
1865
1875
1884
1875
1857
1871
1876
1851
1858
1868
1852
1930
1874
1889
1879
1893
1906
1852
1879
1891
1903
1918
1867
1875
1879
1896
200
195
194
192
192
190
189
187
185
183
182
180
179
178
178
176
175
175
174
174
173
173
171
171
170
170
169
168
165
162
162
162
161
160
159
159
159
158
158
157
157
156
155
154
154
154
153
153
152
151
151
150
150
149
149
149
148
148
148
147
147
146
146
146
146
3.13
3.14
2.75
2.43
3.18
3.42
3.11
2.91
3.15
2.93
2.76
13.68
2.39
3.12
3.00
3.41
3.39
5.21
3.05
2.62
2.71
2.90
2.71
5.11
3.87
2.77
3.05
2.58
2.74
2.45
2.78
2.80
2.84
3.13
2.77
2.55
2.74
3.14
3.50
2.65
2.98
2.91
2.67
3.08
2.99
3.38
2.59
2.37
3.16
2.41
5.16
3.11
3.04
3.14
3.95
5.23
2.30
3.05
2.75
3.16
3.20
2.75
2.66
3.11
3.41
0.102
0.264
0.126
0.202
0.095
0.169
0.219
0.098
0.112
0.166
0.273
0.380
0.122
0.064
0.343
0.154
0.093
0.068
0.140
0.238
0.117
0.169
0.196
0.046
0.041
0.173
0.103
0.070
0.127
0.100
0.177
0.116
0.138
0.070
0.115
0.181
0.209
0.179
0.090
0.194
0.125
0.089
0.146
0.236
0.023
0.049
0.166
0.065
0.182
0.144
0.104
0.224
0.151
0.067
0.216
0.139
0.218
0.155
0.038
0.023
0.149
0.142
0.233
0.027
0.047
15.9
23.9
6.2
14.8
21.1
2.1
22.9
13.7
10.7
18.2
15.8
6.9
5.6
7.0
18.2
20.6
4.9
21.8
16.0
18.5
8.6
20.3
11.8
20.6
4.7
10.3
5.5
11.2
23.2
4.6
10.9
18.4
15.3
11.2
10.4
16.1
14.2
11.5
19.4
12.0
2.2
12.4
12.6
3.2
14.9
4.6
9.1
10.0
4.6
0.7
16.7
13.4
8.0
7.2
12.7
22.0
10.1
3.9
4.4
13.3
26.1
8.6
4.8
7.3
6.7
P
(h)
M
(mag)
Type
16.83
6.58
39
7.274
0.05–0.17
0.12
0.10
0.05–0.20
C
BFC
C
S
9.98
5.225
4.147
0.15–0.2
0.19–0.58
0.04–0.30
7.672
5.988
0.13–0.23
0.16–0.38
5.078
0.04–0.36
P
G
M
CP
C
C
B
S
C
PC
P
C
D
T
C
CP
C
C
DP
C
C
CP
CX
C
S
CP
S
PC
CD
S
S
C
C
X
FC
CX
C
C
CG
XC
C
S
CU
G
S
D
C
X
C
DP
P
S
C
T
C
FCB
CU
C
S
P
9.4
10.37
7
0.13
0.16
0.2–0.4
15.67
13.69
9.763
7.04
18
0.27
0.1
0.11
0.12
0.35–0.42
6.214
0.15
9.03
10.83
7.83
41.8
4.277
7.42
7.6
5.138
11.39
5.93
0.10–0.14
0.07–0.12
0.18
0.12–0.30
0.19
0.12
0.08–0.53
0.10–0.25
0.04–0.11
6.875
8.14
8.9
8.1
10.42
0.15
0.09
0.12
0.08
0.15–0.20
9.35
7.785
0.04–0.1
0.14–0.25
8.098
0.17–0.27
6.888
8
0.31
0.20
11.57
0.22–0.35
12.03
0.20
5.97
13.81
8.333
0.10
0.13
0.07–0.33
p
0.05
0.04
0.25
0.07
0.02
0.08
0.12
0.03
0.07
0.04
0.04
0.03
0.03
0.04
0.03
0.05
0.04
0.06
0.05
0.02
0.06
0.04
0.06
0.05
0.05
0.15
0.05
0.19
0.04
0.06
0.29
0.16
0.05
0.05
0.04
0.06
0.03
0.03
0.04
0.05
0.04
0.05
0.08
0.08
0.19
0.03
0.04
0.02
0.04
0.03
0.04
0.22
0.05
0.04
0.03
0.02
0.08
0.05
0.18
0.03
H
G
U−B
B−V
7.43
7.33
7.55
5.70
7.09
8.08
6.86
6.50
7.86
7.68
7.16
6.62
6.32
7.73
7.68
8.05
8.15
7.88
7.97
7.66
7.72
7.42
7.70
8.30
7.46
7.85
7.50
7.60
7.73
6.62
7.79
6.32
7.87
7.49
5.94
6.57
7.79
7.83
8.08
7.56
8.32
8.38
8.05
7.91
8.18
7.93
6.27
7.36
7.42
6.52
8.26
8.04
8.73
8.15
8.27
8.17
6.41
7.84
8.18
8.30
8.64
7.47
7.87
6.64
8.35
0.23
0.25
0.15
0.24
0.15
0.44
−0.04
0.22
0.15
0.34
−0.06
0.25
0.29
0.17
0.15
0.15
0.43
0.15
0.15
0.15
0.01
0.23
0.15
0.15
−0.06
0.23
0.04
0.28
0.27
0.27
0.15
0.32
0.22
0.15
−0.03
0.14
0.12
0.15
0.15
0.05
0.15
0.51
0.01
0.39
0.48
0.16
0.09
0.06
0.17
0.26
0.15
0.10
0.15
−0.09
0.15
0.15
0.18
0.03
0.28
0.15
0.15
−0.11
0.08
0.48
0.04
0.34
0.68
0.36
0.38
0.68
0.83
0.29
0.47
0.25
0.28
0.39
0.37
0.28
0.51
0.38
0.32
0.30
0.30
0.22
0.34
0.35
0.29
0.40
0.36
0.24
0.36
0.30
0.29
0.34
0.33
0.42
0.29
0.54
0.38
0.31
0.50
0.48
0.32
0.36
0.28
0.28
0.27
0.38
0.36
0.39
0.30
0.38
0.39
0.47
0.47
0.42
0.26
0.33
0.30
0.29
0.19
0.21
0.39
0.36
0.37
0.33
0.70
0.75
0.69
0.67
0.70
0.73
0.70
0.86
0.70
0.71
0.70
0.70
0.77
0.77
0.73
0.67
0.74
0.70
0.70
0.72
0.68
0.69
0.72
0.68
0.85
0.70
0.95
0.71
0.74
0.89
0.88
0.70
0.70
0.69
0.66
0.71
0.73
0.69
0.75
0.68
0.75
0.84
0.77
0.74
0.81
0.73
0.70
0.71
0.69
0.75
0.70
0.85
0.72
0.79
0.73
0.25
0.39
0.46
0.23
0.73
0.72
0.86
0.69
Sp.-V/AQuan/1999/10/10:09:50
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13.1 A STEROIDS OR M INOR P LANETS / 319
Table 13.1. (Continued).
No.
Name
95
489
69
349
762
Arethusa
Comacina
Hesperia
Dembowska
Pulcova
Year of
Discovery
D
(km)
a
e
i
1867
1902
1861
1892
1913
145
144
143
143
142
3.07
3.16
2.98
2.92
3.16
0.144
0.032
0.169
0.091
0.092
12.9
12.9
8.6
8.3
13.0
P
(h)
M
(mag)
8.688
0.24
5.655
4.701
0.20
0.08–0.47
Type
p
H
C
C
M
R
F
0.06
0.03
0.12
0.34
0.03
7.84
8.36
7.10
5.98
8.58
G
U−B
B−V
0.37
0.36
0.23
0.54
0.31
0.71
0.69
0.70
0.93
0.65
0.08
0.15
0.15
0.33
0.50
Note
a Object 2060 Chiron is known to exhibit cometary activity, e.g., IAUC 4770, and is catalogued as comet 95p.
Reference
1. Binzel, R.P., Gehrels, T., & Matthews, M.S., editors, 1989, Asteroids II Database, in Asteroids II (University of Arizona
Press, Tucson), pp. 997–1190
Table 13.2. Near-earth asteroids having permanent designations [1–3].a
No.
433
719
887
1036
1221
1566
1580
1620
1627
1685
1862
1863
1864
1865
1866
1915
1916
1917
1943
1980
1981
2059
2061
2062
2063
2100
2101
2102
2135
2201
2202
2212
2329
2340
2368
2608
3102
3103
3122
3199
3200
3271
3288
3352
3360
Name
Eros
Albert
Alinda
Ganymed
Amor
Icarus
Betulia
Geographos
Ivar
Toro
Apollo
Antinous
Daedalus
Cerberus
Sisyphus
Quetzalcoatl
Boreas
Cuyo
Anteros
Tezcatlipoca
Midas
Baboquivari
Anza
Aten
Bacchus
Ra-Shalom
Adonis
Tantalus
Aristaeus
Oljato
Pele
Hephaistos
Orthos
Hathor
Beltrovata
Seneca
Krok
Eger
Florence
Nefertiti
Phaethon
Ul
Seleucus
McAuliffe
Provisional
designation
q
(AU)
a
e
i
H
Type
1898 DQ
1911 MT
1918 DB
1924 TD
1932 EA1
1949 MA
1950 KA
1951 RA
1929 SH
1948 OA
1932 HA
1948 EA
1971 FA
1971 UA
1972 XA
1953 EA
1953 RA
1968 AA
1973 EC
1950 LA
1973 EA
1963 UA
1960 UA
1976 AA
1977 HB
1978 RA
1936 CA
1975 YA
1977 HA
1947 XC
1972 RA
1978 SB
1976 WA
1976 UA
1977 RA
1978 DA
1981 QA
1982 BB
1981 ET3
1982 RA
1983 TB
1982 RB
1982 DV
1981 CW
1981 VA
1.133
1.189
1.087
1.226
1.083
0.187
1.119
0.828
1.124
0.771
0.647
0.891
0.563
0.576
0.873
1.081
1.250
1.066
1.064
1.085
0.622
1.256
1.048
0.790
0.701
0.469
0.441
0.905
0.794
0.626
1.119
0.362
0.820
0.464
1.234
1.044
1.188
0.907
1.021
1.128
0.140
1.271
1.102
1.186
0.633
1.458
2.584
2.486
2.658
1.919
1.078
2.195
1.245
1.863
1.367
1.471
2.260
1.461
1.080
1.893
2.537
2.272
2.150
1.430
1.710
1.776
2.651
2.265
0.967
1.078
0.832
1.874
1.290
1.599
2.174
2.292
2.168
2.402
0.844
2.105
2.491
2.152
1.406
1.769
1.574
1.271
2.102
2.032
1.879
2.465
0.223
0.540
0.563
0.539
0.436
0.827
0.490
0.335
0.397
0.436
0.560
0.606
0.615
0.467
0.539
0.574
0.450
0.504
0.256
0.365
0.650
0.526
0.537
0.183
0.349
0.437
0.765
0.299
0.503
0.712
0.512
0.833
0.659
0.450
0.414
0.581
0.448
0.355
0.423
0.284
0.890
0.395
0.458
0.369
0.743
10.8
10.8
9.3
26.6
11.9
22.9
52.1
13.3
8.4
9.4
6.4
18.4
22.2
16.1
41.2
20.4
12.8
23.9
8.7
26.9
39.8
11.0
3.8
18.9
9.4
15.8
1.4
64.0
23.0
2.5
8.8
11.8
24.4
5.8
5.3
15.3
8.4
20.9
22.2
33.0
22.1
25.0
5.9
4.8
21.7
11.2
16.0
13.8
9.5
17.7
16.9
14.5
15.6
13.2
14.2
16.3
15.5
14.9
16.8
13.0
19.0
14.9
13.9
15.8
13.9
15.5
15.8
16.6
16.8
17.1
16.1
18.7
16.2
17.9
15.3
17.6
13.9
14.9
19.2
15.2
17.5
15.6
15.4
14.2
14.8
14.6
16.7
15.3
15.8
16.3
S
S
S
S
C
S
S
S
Q
S
SQ
S
S
S
S
S
S
S
TCG
S
C
S?
SG
CSU
SQ
S
QRS
E
S
F
S
D
(km)
17
2
5
41
1
2
8
2
7
12
1
2
3
1
10
0.5
3
6
2
13
3
3
3
1
1
4
1
2
1
2
1
5
4
1
3
1
2
3
6
3
5
2
3
3
2
Pi
(109 yr)
Vc
(km/s)
1.5
1.8
0.5
3.8
1.8
4.0
2.8
1.3
1.0
2.5
15.4
30.6
30.6
16.7
14.0
17.2
20.3
19.9
26.0
20.9
1.3
3.5
17.8
13.4
3.8
30.7
1.3
7.1
6.5
6.3
2.8
2.5
2.0
2.3
0.1
0.4
1.8
14.0
14.2
16.0
15.8
17.9
25.4
34.8
21.0
26.4
14.8
34.6
23.3
16.3
3.9
2.1
17.3
17.0
1.4
35.0
1.4
21.0
0.7
26.6
Category
Amor
Amor
Amor
Amor
Amor
Apollo
Amor
Apollo
Amor
Apollo
Apollo
Apollo
Apollo
Apollo
Apollo
Amor
Amor
Amor
Amor
Amor
Apollo
Amor
Amor
Aten
Apollo
Aten
Apollo
Apollo
Apollo
Apollo
Amor
Apollo
Apollo
Aten
Amor
Amor
Amor
Apollo
Amor
Amor
Apollo
Amor
Amor
Amor
Apollo
Sp.-V/AQuan/1999/10/10:09:50
Page 320
320 / 13
S OLAR S YSTEM S MALL B ODIES
Table 13.2. (Continued.)
No.
3361
3362
3551
3552
3553
3554
3671
3691
3752
3753
3757
3838
3908
3988
4015b
4034
4055
4179
4183
4197
4257
4341
4401
4450
4486
4487
4503
4544
4581
4596
4660
4688
4769
4947
4953
4954
4957
5011
5131
5143
5189
5324
5332
5370
5381
5496
5587
5590
5604
5620
5626
5645
5646
5653
5660
5693
5731
5751
5786
5797
5828
5836
5863
5869
5879
6037
6047
Name
Orpheus
Khufu
Verenia
Don Quixote
Mera
Amun
Dionysus
Camillo
Epona
WilsonHarrington
Magellan
Toutatis
Cuno
Ubasti
Poseidon
Aditi
Pan
Mithra
Pocahontas
Cleobulus
Xanthus
Asclepius
Nereus
Castalia
Ninkasi
Eric
Brucemurray
Ptah
Heracles
Lyapunov
Taranis
Sekhmet
Zeus
Zao
Talos
Bivoj
Tara
Tanith
Provisional
designation
q
(AU)
a
e
i
H
Type
1982 HR
1984 QA
1983 RD
1983 SA
1985 JA
1986 EB
1984 KD
1982 FT
1985 PA
1986 TO
1982 XB
1986 WA
1980 PA
1986 LA
1979 VA
0.819
0.526
1.073
1.209
1.117
0.701
1.003
1.270
0.986
0.484
1.017
0.449
1.043
1.055
1.000
1.209
0.989
2.092
4.233
1.645
0.974
2.196
1.774
1.414
0.998
1.835
1.505
1.926
1.545
2.644
0.323
0.469
0.487
0.714
0.321
0.280
0.543
0.284
0.302
0.515
0.446
0.702
0.459
0.317
0.622
2.7
9.9
9.5
30.8
36.8
23.4
13.6
20.4
55.6
19.8
3.9
29.3
2.2
10.8
2.8
19.0
18.3
16.8
13.0
16.5
15.8
16.3
14.9
15.5
15.1
19.0
15.5
17.4
18.2
16.0
V
1986 PA
1985 DO2
1989 AC
1959 LM
1982 TA
1987 QA
1987 KF
1985 TB
1987 SY
1987 SB
1987 UA
1989 WM
1989 FB
1989 FC
1981 QB
1982 DB
1980 WF
1989 PB
1988 TJ1
1990 MU
1990 SQ
1990 XJ
6743 P-L
1990 BG
1991 VL
1990 UQ
1987 SL
1990 DA
1986 RA
1991 JY
1973 NA
1990 SB
1990 VA
1992 FE
1990 OA
1991 FE
1990 SP
1990 TR
1992 WD5
1974 MA
1993 EA
1988 VP4
1992 AC
1991 RC
1980 AA
1991 AM
1993 MF
1983 RB
1988 VN4
1992 CH1
1988 EG
1991 TB1
0.589
1.226
0.920
0.718
0.523
0.876
0.588
1.117
0.596
0.743
1.217
1.279
0.781
0.657
1.077
0.953
1.081
0.549
1.139
0.555
1.104
1.223
0.818
0.639
0.419
0.810
1.136
1.176
1.228
0.667
0.881
1.080
0.710
0.551
1.247
1.201
0.830
1.205
1.248
0.424
0.527
0.786
1.215
0.187
1.053
0.517
1.143
1.097
1.231
1.154
0.636
0.942
1.060
1.820
2.512
1.980
2.298
1.647
1.835
2.578
1.442
2.200
1.731
2.703
1.042
1.022
2.239
1.490
2.232
1.063
1.370
1.621
2.001
1.565
1.635
1.486
1.835
1.551
2.958
2.163
3.344
0.947
2.433
2.392
0.985
0.927
2.159
2.196
1.355
2.143
1.794
1.786
1.272
2.267
2.104
1.081
1.893
1.698
2.443
2.222
1.812
1.625
1.269
1.454
0.444
0.326
0.634
0.638
0.773
0.468
0.679
0.567
0.586
0.663
0.297
0.527
0.250
0.357
0.519
0.360
0.516
0.483
0.168
0.658
0.448
0.219
0.500
0.570
0.771
0.478
0.616
0.456
0.633
0.296
0.638
0.548
0.279
0.405
0.422
0.453
0.387
0.438
0.304
0.763
0.585
0.653
0.423
0.827
0.444
0.696
0.532
0.506
0.321
0.289
0.499
0.352
11.2
23.2
0.5
6.8
12.2
40.7
11.9
26.7
5.5
3.0
16.4
2.5
14.1
4.9
37.1
1.4
6.4
8.9
15.6
24.4
17.5
35.0
7.4
36.4
9.2
3.6
19.5
25.4
19.0
49.0
68.0
18.1
14.2
4.8
7.8
3.9
13.5
7.9
6.9
38.0
5.1
11.5
16.1
23.3
4.2
30.0
8.0
19.4
17.9
21.6
3.5
23.5
18.1
14.8
15.3
14.4
14.6
16.2
15.5
15.8
17.2
15.6
17.1
15.6
17.1
20.4
16.0
18.2
19.0
16.9
18.7
14.1
12.6
15.1
17.1
14.1
14.0
17.3
15.2
13.9
15.7
16.5
15.3
13.6
19.7
16.4
17.0
14.7
17.0
14.3
15.4
15.7
17.0
15.8
14.8
17.0
19.1
16.3
13.9
15.5
17.0
17.9
18.7
17.0
V
D
M
S
V
CF
V
SQ
S
S
C
S
S
D
(km)
Pi
(109 yr)
1
1
1
18
2
3
2
4
3
4
0.5
3
1
1
4
21.0
5.3
14.0
19.8
5.4
1.5
17.4
16.0
1.0
3.0
5.1
1.0
4.0
27.0
22.0
13.4
29.0
14.7
0.8
15.5
1
3
3
5
5
2
3
3
1
3
1
3
1
0.5
2
1
0.5
2
1
6
12
4
1
6
6
1
3
6
5
2
3
7
0.5
2
2
4
2
5
3
3
2
3
4
2
1
2
6
3
2
1
1
2
Vc
(km/s)
1.3
1.0
21.3
27.0
1.5
23.3
6.4
5.5
22.2
18.5
6.6
13.3
0.8
22.5
1.1
4.2
15.5
15.4
21.8
13.1
20.9
18.9
0.6
26.5
3.8
0.6
16.7
26.3
5.8
17.2
2.9
0.5
26.7
40.5
5.4
16.5
1.6
4.0
16.4
17.0
0.9
32.0
1.0
20.1
0.3
0.5
13.2
28.0
8.8
18.3
Category
Apollo
Aten
Amor
Amor
Amor
Aten
Amor
Amor
Apollo
Aten
Amor
Apollo
Amor
Amor
Amor
Apollo
Amor
Apollo
Apollo
Apollo
Apollo
Apollo
Amor
Apollo
Apollo
Amor
Amor
Apollo
Apollo
Amor
Apollo
Amor
Apollo
Amor
Apollo
Amor
Amor
Apollo
Apollo
Apollo
Apollo
Amor
Amor
Amor
Aten
Apollo
Amor
Aten
Aten
Amor
Amor
Apollo
Amor
Amor
Apollo
Apollo
Apollo
Amor
Apollo
Amor
Apollo
Amor
Amor
Amor
Amor
Apollo
Apollo
Sp.-V/AQuan/1999/10/10:09:50
Page 321
13.2 C OMETS / 321
Table 13.2. (Continued.)
No.
6050
6053
6063
6178
6239
6455
6456
6489
6491
6569
6611
7025
7088
7092
7236
7335
7336
7341
7350
7358
7474
7480
7482
7753
7822
7839
7888
7889
7977
8013
8014
8034
8035
8037
Name
Jason
Minos
Golombek
Golevka
Ishtar
Cadmus
Norwan
Hermesc
Provisional
designation
q
(AU)
a
e
i
H
1992 AE
1993 BW3
1984 KB
1986 DA
1989 QF
1992 HE
1992 OM
1991 JX
1991 OA
1993 MO
1993 VW
1993 QA
1992 AA
1992 LC
1987 PA
1989 JA
1989 RS1
1991 VK
1993 VA
1995 YA3
1992 TC
1994 PC
1994 PC1
1988 XB
1991 CS
1994 ND
1993 UC
1994 LX
1977 QQ5
1990 KA
1990 MF
1992 LR
1992 TB
1993 HO1
1937 UB
1.240
1.010
0.522
1.174
0.676
0.959
1.298
1.011
1.036
1.267
0.873
1.011
1.208
0.744
1.185
0.913
1.195
0.909
0.825
1.095
1.108
1.071
0.905
0.761
0.938
1.047
0.819
0.825
1.189
1.246
0.950
1.082
0.721
1.159
0.618
2.202
2.146
2.216
2.817
1.151
2.241
2.194
2.517
2.508
1.626
1.695
1.476
1.981
2.522
2.717
1.771
2.305
1.842
1.356
2.198
1.566
1.568
1.346
1.468
1.123
2.166
2.436
1.262
2.226
2.198
1.746
1.830
1.342
1.987
1.644
0.437
0.529
0.764
0.583
0.413
0.572
0.409
0.598
0.587
0.221
0.485
0.315
0.390
0.705
0.564
0.484
0.481
0.507
0.391
0.502
0.292
0.317
0.328
0.482
0.165
0.517
0.664
0.346
0.466
0.433
0.456
0.409
0.462
0.417
0.624
6.4
21.6
4.8
4.3
3.9
37.4
8.2
2.3
5.5
22.6
8.7
12.6
8.3
17.8
16.4
15.2
7.2
5.4
7.3
4.7
7.1
9.5
33.5
3.1
37.1
27.2
26.0
36.9
25.2
7.6
1.9
2.0
28.3
5.9
6.1
15.4
15.1
15.3
15.1
17.9
13.8
15.9
19.2
18.5
16.5
16.5
18.3
16.7
15.4
18.4
17.0
18.7
16.7
17.3
14.4
18.0
17.2
16.8
18.6
17.4
17.9
15.3
15.3
15.4
16.6
18.7
17.9
17.3
16.6
18.0
Type
S
M
D
(km)
3
4
3
4
1
7
3
1
1
2
2
1
2
3
1
2
1
2
1
5
1
1
2
1
1
1
3
3
3
1
0.5
1
1
1
1
Pi
(109 yr)
Vc
(km/s)
1.1
28.8
6.4
17.9
2.8
17.5
6.2
5.0
17.0
22.0
16.6
14.1
2.2
21.7
Category
Amor
Amor
Apollo
Amor
Apollo
Apollo
Amor
Amor
Amor
Amor
Apollo
Amor
Amor
Apollo
Amor
Apollo
Amor
Apollo
Apollo
Amor
Amor
Amor
Apollo
Apollo
Apollo
Amor
Apollo
Apollo
Amor
Amor
Apollo
Amor
Apollo
Amor
Apollo
Notes
a Collision probabilities are available only for objects discovered prior to mid-1991. These values are presented only
for objects which can evolve into an Earth-intersecting orbit.
b Object 4015 Wilson–Harrington is also catalogued as comet 107P.
c Object Hermes received a permanent name upon discovery, but is currently lost.
References
1. IAU Minor Planet Center web page as of 1998 January 1. http://cfa.www.harvard.edu/cfa/ps/mpc.html
2. The Spaceguard Survey, Report of the NASA International Near-Earth Object Detection Workshop (1992)
3. T. Gehrels, editor, 1994, Hazards Due to Comets and Asteroids, (University of Arizona Press, Tucson)
13.2
13.2.1
COMETS
Locations and Populations [6, 7, 2]
The source region for long-period and high-inclination, short-period comets is the Oort cloud.
Estimated distance: 103 to 105 AU.
Estimated number of comets: 1011 –1013 .
Estimated total mass: 1025 –1027 kg.
The primary source for low-inclination, short-period comets is the Kuiper belt.
Estimated distance: 30 to 1000 AU.
Estimated number of comets: 108 –1012 .
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S OLAR S YSTEM S MALL B ODIES
Estimated total mass: 1022 –1026 kg.
Total number known as of 1998, January 1: 60.
Short-period comets, defined as orbital period P < 200 yr.
Total number known as of 1998, January 1: 193.
Average number of apparitions per year: 17.
Typical discovery rate per year for new comets: 6.
Mean semimajor axis: a = 5.8 AU.
Mean orbital eccentricity: e = 0.6.
Mean inclination: i = 19 deg.
Long-period comets, defined as orbital period P > 200 yr.
Total number known as of 1998, January 1: 756.
Typical discovery rate per year for new comets: 6.
Estimated semimajor axes: 102 –105 AU.
Typical orbital eccentricity: e ∼ 1.
Inclinations are isotropic.
13.2.2
Magnitudes [6]
A comet’s absolute magnitude, Ho , is defined as its integrated V magnitude if it were observed at a
distance r = 1 AU from the Sun, = 1 AU from the Earth, and zero phase angle. At other distances,
a comet’s integrated V magnitude can be estimated by
V = Ho + 2.5n log r + 5 log .
Typical range for n: 2 to 8.
Average value: n ∼ 4.
For a body with no coma, tail, or emission: n = 2.
13.2.3
Physical Properties [6–8]
Nucleus:
Diameter range: 1.0–40 km (Halley = 16 × 8 × 7 km).
Mass range: 1014 –1019 g (Halley = 1017 –1018 g).
Density range: 0.1–1.1 g cm−3 (Halley estimates: 0.2 to 1.1 g cm−3 ).
Estimated albedo range: 0.01–0.05 (Halley = 0.035).
Typical rotation period: 12 h (Halley = 2.2 and 7.4 days).
Typical dust production rate at 1 AU: 104 –106 g/s.
Typical gas production rate at 1 AU: 1028 –1030 molecules/s.
Gas/dust expansion rate at 1 AU: 0.5 to 1.0 km/s.
Typical dust/gas ratio (by mass): 1.0 to 2.0.
Typical mass loss per apparition: 0.05 to 1.0 percent of total mass.
Estimated composition of ices: H2 O (80%), CO (3–7%), CO2 (3%), CH3 OH (1–6%), plus CH3 CN,
(H2 CO)n , HCN.
Estimated composition of grains: Mg-rich silicates, refractory organics.
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13.2 C OMETS / 323
Coma:
Typical radius: 104 –105 km.
Typical composition: H2 O, CO, CO2 , OH, H2 CO, CH3 OH, CH3 CN, CN, C2 , C3 .
Hydrogen cloud:
Typical radius: 107 km.
Typical production rate at 1 AU: 1028 –1030 H atoms/s.
Ion Tail (Type I):
Typical length: 106 –108 km.
Direction: antisolar.
+
+
Principal species: CO+ , H2 O+ , CO+
2 , OH , H3 O .
Dust Tail (Type II):
Typical length: 106 –107 km.
Direction: Initially antisolar, becoming curved as dust particles follow independent orbits.
Particle size range: 0.1 to 100 microns.
Typical particle composition: silicates and refractory organics.
13.2.4
Comet Data Tables
Table 13.3 lists short-period comets with more than one apparition, while Table 13.4 lists those with
only one appearance. Table 13.5 gives selected long-period comets. Table 13.6 lists probable cometary
nature objects.
Table 13.3. Short period comets having more than one known apparition [1].
Comet Name
2P
107Pa
26P
79P
96P
45P
73P
25D
5D
41P
10P
9P
46P
71P
88P
11D
100P
83P
37P
116P
103P
54P
81P
7P
6P
57P
104P
31P
76P
Encke
Wilson–Harrington
Grigg–Skjellerup
du Toit–Hartley
Machholz
Honda–Mrkos–Pajdusakova
Schwassmann–Wachmann 3
Neujmin 2
Brorsen
Tuttle–Giacobini–Kresak
Tempel 2
Tempel 1
Wirtanen
Clark
Howell
Tempel–Swift
Hartley 1
Russell 1
Forbes
Wild 4
Hartley 2
de Vico–Swift
Wild 2
Pons–Winnecke
d’Arrest
du Toit–Neujmin–Delporte
Kowal 2
Schwassmann–Wachmann 2
West–Kohoutek–Ikemura
Perihelion Orbital
date
period Perihelion
Orbital
Longitude
Longitude
Orbital
Apehelion
(Year)
(yrs)
(AU)
eccentricity of perihelion of asc. node inclination
(AU)
1994.1
1992.6
1992.6
1987.4
1991.6
1990.7
1990.4
1927.0
1879.2
1990.1
1994.2
1994.5
1991.7
1989.9
1993.2
1908.8
1991.4
1985.5
1993.2
1996.7
1991.7
1965.3
1991.0
1989.6
1989.1
1989.8
1991.8
1994.1
1994.0
3.28
4.29
5.10
5.21
5.24
5.30
5.35
5.43
5.46
5.46
5.48
5.50
5.50
5.51
5.58
5.68
6.02
6.10
6.13
6.16
6.26
6.31
6.37
6.38
6.39
6.39
6.39
6.39
6.41
0.33
1.00
1.00
1.20
0.13
0.54
0.94
1.34
0.59
1.07
1.48
1.49
1.08
1.56
1.41
1.15
1.82
1.61
1.45
1.99
0.95
1.62
1.58
1.26
1.29
1.72
1.50
2.07
1.58
0.850
0.623
0.664
0.601
0.958
0.822
0.694
0.567
0.810
0.656
0.522
0.520
0.652
0.501
0.552
0.638
0.451
0.517
0.568
0.408
0.719
0.524
0.541
0.634
0.625
0.502
0.564
0.399
0.543
186.3
90.9
359.3
251.6
14.5
325.8
198.8
193.7
14.9
61.6
194.9
178.9
356.2
209.0
234.8
113.4
178.8
0.4
310.5
170.8
174.9
325.4
41.6
172.3
177.1
115.3
189.5
358.2
360.0
334.7
271.1
213.3
309.3
94.5
89.3
69.9
328.7
103.0
141.6
118.2
69.0
82.3
59.7
57.7
291.8
38.9
230.8
334.5
22.1
226.8
25.1
136.2
93.4
139.5
189.1
247.8
126.2
84.2
11.9
2.8
21.1
2.9
60.1
4.2
11.4
10.6
29.4
9.2
12.0
10.6
11.7
9.5
4.4
5.4
25.7
22.7
7.2
3.7
9.3
3.6
3.2
22.3
19.4
2.8
15.8
3.8
30.5
4.09
4.29
4.93
4.81
5.91
5.54
5.18
4.84
5.61
5.14
4.73
4.73
5.15
4.68
4.88
5.22
4.80
5.06
5.25
4.73
5.84
5.21
5.30
5.62
5.59
5.17
5.38
4.82
5.33
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S OLAR S YSTEM S MALL B ODIES
Table 13.3. (Continued.)
Comet Name
105P
22P
43P
87P
114P
94P
67P
21P
3D
44P
112P
75P
62P
18P
51P
49P
60P
65P
110P
19P
16P
86P
15P
84P
48P
69P
77P
33P
17P
113P
98P
108P
106P
102P
30P
4P
89P
47P
61P
91P
52P
97P
70P
39P
78P
50P
83P
80P
111P
24P
14P
58P
36P
74P
115P
32P
59P
72P
93P
64P
42P
40P
68P
34P
85P
56P
53P
Singer Brewster
Kopff
Wolf–Harrington
Bus
Wiseman–Skiff
Russell 4
Churyumov–Gerasimenko
Giacobini–Zinner
Biela
Reinmuth 2
Urata–Niijima
Kohoutek
Tsuchinshan 1
Perrine–Mrkos
Harrington
Arend–Rigaux
Tsuchinshan 2
Gunn
Hartley 3
Borrelly
Brooks 2
Wild 3
Finlay
Giclas
Johnson
Taylor
Longmore
Daniel
Holmes
Spitaler
Takamizawa
Ciffreo
Schuster
Shoemaker 1
Reinmuth 1
Faye
Russell 2
Ashbrook–Jackson
Shajn–Schaldach
Russell 3
Harrington–Abell
Metcalf–Brewington
Kojima
Oterma
Gehrels 2
Arend
Gehrels 3
Peters–Hartley
Helin–Roman–Crockett
Schaumasse
Wolf
Jackson–Neujmin
Whipple
Smirnova–Chernykh
Maury
Comas Sola
Kearns–Kwee
Denning–Fujikawa
Lovas 1
Swift–Gehrels
Neujmin 3
Vaisala 1
Klemola
Gale
Boethin
Slaughter–Burnham
Van Biesbroeck
Perihelion Orbital
date
period Perihelion
Orbital
Longitude
Longitude
Orbital
Apehelion
(Year)
(yrs)
(AU)
eccentricity of perihelion of asc. node inclination
(AU)
1992.8
1990.1
1991.3
1994.5
1993.4
1990.5
1989.5
1992.3
1852.7
1994.5
1993.5
1987.8
1991.7
1968.8
1994.6
1991.8
1992.4
1989.7
1994.4
1988.0
1994.7
1994.6
1988.4
1992.7
1990.9
1991.0
1988.8
1992.7
1993.3
1994.1
1991.6
1993.1
1992.7
1992.0
1988.4
1991.9
1994.8
1993.5
1993.9
1990.4
1991.5
1991.0
1994.1
1958.4
1989.8
1991.4
1993.6
1990.5
1996.8
1993.2
1992.7
1987.4
1995.0
1992.6
1994.2
1987.6
1990.9
1978.8
1989.8
1991.2
1993.9
1993.3
1987.6
1938.5
1986.0
1993.5
1991.3
6.43
6.46
6.51
6.52
6.53
6.57
6.59
6.61
6.62
6.64
6.64
6.65
6.65
6.72
6.78
6.82
6.82
6.84
6.84
6.86
6.89
6.91
6.95
6.96
6.97
6.97
7.00
7.06
7.09
7.10
7.22
7.23
7.26
7.26
7.29
7.34
7.38
7.49
7.49
7.50
7.59
7.76
7.85
7.88
7.94
7.99
8.11
8.13
8.16
8.22
8.25
8.42
8.53
8.57
8.74
8.78
8.96
9.01
9.09
9.21
10.6
10.8
10.9
11.0
11.2
11.6
12.4
2.03
1.59
1.61
2.18
1.51
2.22
1.30
1.03
0.86
1.89
1.46
1.78
1.50
1.27
1.57
1.44
1.78
2.47
2.46
1.36
1.84
2.30
1.09
1.85
2.31
1.95
2.41
1.65
2.18
2.13
1.59
1.71
1.54
1.99
1.87
1.59
2.28
2.32
2.35
2.52
1.77
1.59
2.40
3.39
2.35
1.85
3.43
1.63
3.49
1.20
2.43
1.44
3.09
3.57
2.03
1.83
2.22
0.78
1.68
1.36
2.00
1.78
1.77
1.18
1.11
2.54
2.40
0.414
0.543
0.539
0.375
0.568
0.366
0.630
0.706
0.756
0.464
0.588
0.498
0.576
0.643
0.561
0.600
0.504
0.314
0.317
0.624
0.491
0.366
0.699
0.493
0.366
0.466
0.341
0.552
0.410
0.422
0.575
0.543
0.590
0.470
0.503
0.578
0.400
0.395
0.388
0.343
0.540
0.594
0.393
0.144
0.410
0.537
0.151
0.598
0.139
0.705
0.406
0.653
0.259
0.147
0.522
0.570
0.487
0.820
0.614
0.692
0.586
0.635
0.640
0.761
0.778
0.504
0.553
46.6
162.9
187.0
24.4
171.9
93.0
11.4
172.5
223.2
45.9
21.5
175.7
22.8
166.0
233.5
329.1
203.1
197.0
168.4
353.3
198.0
179.3
322.3
276.5
208.3
355.6
195.7
11.0
23.2
50.2
147.7
358.0
355.7
18.8
13.1
203.9
249.2
348.7
216.6
353.2
138.7
208.0
348.5
354.9
183.5
47.1
231.6
338.3
10.2
57.5
162.3
196.6
201.9
89.0
119.8
45.5
131.8
334.1
73.6
84.8
147.0
47.4
154.5
209.2
11.7
44.1
134.2
192.6
120.9
254.9
182.2
271.7
71.0
51.0
195.4
248.0
296.2
31.9
269.7
96.8
240.9
119.3
122.1
288.3
68.5
287.9
75.4
176.9
72.6
42.4
112.5
117.3
108.9
15.7
69.1
328.0
14.5
124.9
53.7
50.6
340.0
119.8
199.6
42.5
2.7
166.9
248.7
337.3
187.8
154.8
155.8
216.3
356.2
243.3
260.1
92.0
81.1
204.1
163.8
182.5
77.5
176.8
61.1
315.8
41.6
342.4
314.4
150.4
135.1
176.5
67.9
26.5
346.4
149.1
9.2
4.7
18.5
2.6
18.2
6.2
7.1
31.8
12.5
7.0
24.2
5.9
10.5
17.8
8.7
17.9
6.7
10.4
11.7
30.3
5.5
15.5
3.7
7.3
13.7
20.6
24.4
20.1
19.2
5.8
9.5
13.1
20.1
26.2
8.1
9.1
12.0
12.5
6.1
14.1
10.2
13.0
0.9
4.0
6.7
19.9
1.1
29.8
4.2
11.8
27.5
14.1
9.9
6.6
11.7
13.0
9.0
8.7
12.2
9.3
4.0
11.6
10.9
11.7
5.8
8.2
6.6
4.89
5.35
5.37
4.80
5.47
4.79
5.73
6.01
6.19
5.17
5.61
5.30
5.57
5.85
5.59
5.75
5.41
4.74
4.75
5.86
5.40
4.96
6.19
5.44
4.98
5.35
4.91
5.71
5.21
5.25
5.88
5.77
5.96
5.51
5.65
5.96
5.31
5.34
5.31
5.15
5.95
6.25
5.50
4.53
5.61
6.14
4.64
6.46
4.61
6.94
5.74
6.84
5.25
4.81
6.46
6.68
6.42
7.88
7.03
7.43
7.67
7.98
8.09
8.70
8.91
7.70
8.33
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13.2 C OMETS / 325
Table 13.3. (Continued.)
Perihelion Orbital
date
period Perihelion
Orbital
Longitude
Longitude
Orbital
Apehelion
(Year)
(yrs)
(AU)
eccentricity of perihelion of asc. node inclination
(AU)
Comet Name
92P
63P
8P
101P
29P
66P
99P
90P
28P
27P
55P
38P
95Pb
20D
13P
23P
121P
1P
109P
35P
Sanguin
Wild 1
Tuttle
Chernykh
Schwassmann–Wachmann 1
du Toit
Kowal 1
Gehrels 1
Neujmin 1
Crommelin
Tempel–Tuttle
Stephan–Oterma
Chiron
Westphal
Olbers
Brorsen–Metcalf
Pons–Brooks
Halley
Swift–Tuttle
Herschel–Rigollet
1990.2
1973.5
1994.5
1992.1
1989.8
1974.2
1992.2
1987.6
1984.8
1984.1
1965.3
1980.9
1996.1
1913.9
1956.5
1989.7
1954.4
1986.1
1993.0
1939.6
12.5
13.3
13.5
14.0
14.9
15.0
15.0
15.1
18.2
27.4
32.9
37.7
50.7
61.9
69.6
70.5
70.9
76.0
135.
155.
1.81
1.98
1.00
2.36
5.77
1.29
4.67
2.99
1.55
0.74
0.98
1.57
8.45
1.25
1.18
0.48
0.77
0.59
0.96
0.75
0.663
0.647
0.824
0.594
0.045
0.787
0.233
0.510
0.776
0.919
0.904
0.860
0.383
0.920
0.930
0.972
0.955
0.967
0.964
0.974
162.8
167.9
206.7
263.2
49.9
257.2
174.5
28.5
346.8
195.8
172.6
358.2
339.6
57.1
64.6
129.6
199.0
111.9
153.0
29.3
182.5
358.9
270.5
130.4
312.8
22.8
28.8
13.6
347.0
250.9
235.1
79.2
209.4
348.0
86.1
311.6
255.9
58.9
139.4
356.0
18.7
19.9
54.7
5.1
9.4
18.7
4.4
9.6
14.2
29.1
162.7
18.0
6.9
40.9
44.6
19.3
74.2
162.2
113.4
64.2
8.96
9.24
10.3
9.24
6.31
10.9
7.50
9.21
12.3
17.4
19.6
20.9
19.0
30.0
32.6
33.7
33.5
35.3
51.7
56.9
Notes
a Object 107P, Wilson–Harrington is also catalogued as minor planet 4015.
b Object 95P, Chiron is also catalogued as minor planet 2060.
Reference
1. Marsden, B.G., & Williams, G.V. 1995, Catalogue of Cometary Orbits, 10th ed., IAU Central Bureau for Astronomical
Telegrams and Minor Planet Center
Table 13.4. Short-period comets having one known apparition [1].
Comet
Name
D/1766 G1
D/1819 W1
P/1994 P1
D/1884 O1
D/1886 K1
P/1991 R2
D/1770 L1
P/1991 F1
D/1783 W1
D/1978 R1
P/1990 R2
D/1978 C2
D/1952 B1
P/1991 C2
D/1892 T1
P/1990 R1
D/1896 R2
D/1918 W1
P/1991 S1
P/1991 V2
P/1986 W1
D/1895 Q1
P/1991 C1
D/1984 H1
P/1994 A1
P/1993 X1
D/1894 F1
P/1992 G2
D/1977 C1
P/1991 V1
Helfenzrieder
Blanpain
Machholz 2
Barnard 1
Brooks 1
Spacewatch
Lexell
Mrkos
Pigott
Haneda–Campos
Holt–Olmstead
Tritton
Harrington–Wilson
Shoemaker–Levy 4
Barnard 3
Mueller 2
Giacobini
Schorr
McNaught–Hughes
Shoemaker–Levy 7
Lovas 2
Swift
Shoemaker–Levy 3
Kowal–Mrkos
Kushida
Kushida–Muramatsu
Denning
Shoemaker–Levy 8
Skiff–Kosai
Shoemaker–Levy 6
Perihelion
date
(Year)
1766.3
1819.9
1994.7
1884.6
1886.4
1991.0
1770.6
1991.2
1783.9
1978.8
1990.8
1977.8
1951.8
1990.5
1892.9
1990.9
1896.8
1918.8
1991.4
1991.8
1986.7
1895.6
1990.9
1984.4
1994.0
1993.9
1894.1
1992.5
1976.6
1991.8
Orbital
period Perihelion
(yrs)
(AU)
4.35
5.10
5.23
5.38
5.44
5.59
5.60
5.64
5.89
5.97
6.16
6.35
6.36
6.51
6.52
6.56
6.65
6.67
6.70
6.72
6.75
7.20
7.25
7.32
7.36
7.40
7.42
7.47
7.54
7.57
0.41
0.89
0.75
1.28
1.33
1.54
0.67
1.41
1.46
1.10
2.04
1.44
1.66
2.02
1.43
2.08
1.46
1.88
2.12
1.63
1.46
1.30
2.81
1.95
1.37
2.75
1.15
2.71
2.85
1.13
Orbital
eccentricity
Longitude
of perihelion
0.848
0.699
0.750
0.583
0.571
0.511
0.786
0.555
0.552
0.665
0.392
0.580
0.515
0.421
0.590
0.406
0.588
0.469
0.404
0.542
0.592
0.652
0.250
0.483
0.639
0.277
0.698
0.291
0.259
0.706
178.7
350.3
149.3
301.1
176.9
87.1
225.0
180.4
354.7
240.5
2.6
147.7
343.0
302.2
170.0
171.0
140.5
279.3
223.2
91.7
71.3
167.8
181.7
338.0
214.5
348.3
46.4
22.4
26.6
333.1
Longitude
of asc. node
76.3
79.8
246.2
6.8
55.1
153.4
134.5
1.7
58.7
132.2
15.3
300.8
128.5
152.1
208.0
218.9
194.9
119.0
90.2
313.0
283.8
171.8
303.8
249.3
245.9
93.7
85.7
213.4
80.8
37.9
Orbital
Aphelion
inclination
(AU)
7.9
9.1
12.8
5.5
12.7
10.0
1.6
31.5
45.1
5.9
14.9
7.0
16.3
8.5
31.3
7.1
11.4
5.6
7.3
10.3
1.5
3.0
5.0
3.0
4.2
2.4
5.5
6.1
3.2
16.9
4.92
5.03
5.27
4.86
4.86
4.76
5.63
4.92
5.06
5.48
4.68
5.42
5.20
4.95
5.55
4.93
5.62
5.21
4.99
5.49
5.69
6.16
4.68
5.59
6.20
4.85
6.46
4.93
4.84
6.58
Sp.-V/AQuan/1999/10/10:09:50
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326 / 13
S OLAR S YSTEM S MALL B ODIES
Table 13.4. (Continued.)
Comet
Name
P/1989 E3
D/1984 W1
P/1989 E2
P/1989 U1
P/1987 U2
P/1990 S1
P/1991 T1
P/1989 E1
P/1992 G3
P/1990 UL3
P/1993 K2
P/1989 T2
P/1987 U1
P/1992 Q1
P/1988 V1
P/1983 M1
P/1993 W1
P/1987 G3
P/1994 J3
D/1960 S1
P/1983 C1
P/1983 J3
P/1986 A1
P/1990 V1
D/1993 F2
P/1994 X1
P/1994 N2
P/1983 V1
P/1991 L3
D/1827 M1
D/1921 H1
D/1846 D1
D/1989 A3
D/1942 EA
D/1889 M1
D/1917 F1
D/1984 A1
D/1937 D1
West–Hartley
Shoemaker 2
Shoemaker–Holt 2
Helin–Roman–Alu 2
Mueller 1
Mueller 3
Shoemaker–Levy 5
Parker–Hartley
Mueller 4
Shoemaker–Levy 2
Helin–Lawrence
Helin–Roman–Alu 1
Shoemaker–Holt 1
Brewington
Ge–Wang
IRAS
Mueller 5
Helin
Shoemaker 4
van Houten
Bowell–Skiff
Kowal–Vavrova
Shoemaker 3
Shoemaker–Levy 1
Shoemaker–Levy 9
McNaught–Russell
McNaught–Hartley
Hartley–IRAS
Levy
Pons–Gambart
Dubiago
de Vico
Bradfield 2
Vaisala 2
Barnard 2
Mellish
Bradfield 1
Wilk
Perihelion
date
(Year)
1988.8
1984.7
1988.6
1989.8
1987.9
1990.6
1991.9
1987.6
1992.1
1990.7
1993.5
1987.8
1988.4
1992.4
1988.4
1983.6
1994.7
1987.6
1994.8
1961.3
1983.2
1983.2
1986.0
1990.7
1994.2
1994.7
1994.9
1984.0
1991.5
1827.4
1921.3
1846.2
1988.9
1942.1
1889.5
1917.3
1984.0
1937.1
Orbital
period Perihelion
(yrs)
(AU)
7.59
7.84
8.01
8.19
8.45
8.65
8.66
8.85
8.97
9.28
9.45
9.50
9.55
10.7
11.3
13.2
13.8
14.5
14.6
15.6
15.7
15.9
16.9
17.3
17.7
18.4
20.8
21.5
51.3
57.5
62.3
76.3
81.9
85.4
145.
145.
151.
187.
2.13
1.32
2.65
1.93
2.75
3.00
1.98
3.03
2.64
1.84
3.09
3.71
3.05
1.60
2.52
1.70
4.25
2.57
2.94
3.96
1.95
2.61
1.79
1.52
5.38
1.28
2.49
1.28
0.98
0.81
1.12
0.66
0.42
1.29
1.11
0.19
1.36
0.62
Orbital
eccentricity
Longitude
of perihelion
0.449
0.666
0.339
0.525
0.338
0.288
0.529
0.292
0.389
0.582
0.309
0.174
0.322
0.671
0.501
0.696
0.261
0.567
0.507
0.367
0.689
0.588
0.728
0.772
0.207
0.817
0.671
0.834
0.929
0.946
0.929
0.963
0.978
0.934
0.960
0.993
0.952
0.981
102.7
317.6
5.9
200.7
30.3
226.0
6.0
181.3
43.6
140.1
163.7
216.3
210.4
47.8
176.1
356.9
30.0
216.3
192.2
14.4
169.0
19.5
14.9
310.6
355.0
171.1
312.2
47.1
41.5
19.2
97.4
12.9
194.7
335.2
60.2
121.3
219.2
31.5
Longitude
of asc. node
46.8
55.5
99.8
203.0
4.6
138.0
29.7
244.3
145.4
236.0
92.0
73.5
214.6
343.7
180.5
357.9
100.7
143.7
92.9
23.6
346.3
202.6
97.3
52.0
220.9
218.0
36.0
1.5
329.4
320.0
67.2
79.7
28.4
172.3
272.6
88.7
356.9
58.3
Orbital
Aphelion
inclination
(AU)
15.4
21.6
17.7
7.4
8.8
9.4
11.8
5.2
29.8
4.6
9.9
9.8
4.4
18.1
11.7
46.2
16.5
4.7
24.8
6.7
3.8
4.3
6.4
24.3
5.8
29.1
17.6
95.7
19.2
136.5
22.3
85.1
83.1
38.0
31.2
32.7
51.8
26.0
5.59
6.57
5.36
6.19
5.55
5.43
6.45
5.53
6.00
6.99
5.85
5.27
5.95
8.12
7.58
9.45
7.24
9.30
8.99
8.54
10.6
10.1
11.4
11.8
8.20
12.70
12.60
14.2
26.6
29.0
30.3
35.3
37.3
37.5
54.2
55.1
55.5
64.9
Reference
1. Marsden, B.G., & Williams, G.V. 1995, Catalogue of Cometary Orbits, 10th ed., IAU Central Bureau for Astronomical
Telegrams and Minor Planet Center
Table 13.5. Selected long-period comets [1, 2].
Comet
Name
Designation
Discovery date
(Year)
Perihelion
(AU)
Orbital
eccentricity
Orbital
inclination
C/1843 D1
C/1858 L1
C/1882 R1
C/1908 R1
C/1956 R1
C/1965 S1
C/1969 Y1
C/1973 E1
C/1975 V1
C/1980 E1
C/1983 H1
C/1988 F1
Great March Comet of 1843
Donati
Great September Comet of 1882
Morehouse
Arend–Roland
Ikeya–Seki
Bennett
Kohoutek
West
Bowell
IRAS–Araki–Alcock
Levy
1843 I
1858 VI
1882 II
1908 III
1957 III
1965 VIII
1970 II
1973 XII
1976 VI
1982 I
1983 VII
1987 XXX
1843
1858
1882
1908
1956
1965
1970
1973
1976
1980
1983
1988
0.005
0.58
0.008
0.95
0.32
0.008
0.54
0.14
0.20
3.36
0.99
1.17
1.000
0.996
1.000
1.001
1.000
1.000
0.996
1.000
1.000
1.057
0.990
0.998
144.3
117.0
142.0
140.2
119.9
141.9
90.0
14.3
43.1
1.7
73.3
62.8
Sp.-V/AQuan/1999/10/10:09:50
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13.2 C OMETS / 327
Table 13.5. (Continued.)
Comet
Name
Designation
C/1988 J1
C/1990 K1
C/1991 C3
C/1992 J2
C/1995 O1
C/1996 B2
Shoemaker–Holt
Levy
McNaught–Russell
Bradfield
Hale–Bopp
Hyakutake
1988 III
1990 XX
1990 XIX
1992 XIII
—
—
Discovery date
(Year)
Perihelion
(AU)
Orbital
eccentricity
Orbital
inclination
1988
1990
1991
1992
1995
1996
1.17
0.94
4.78
0.59
0.91
0.23
0.998
1.000
1.002
1.000
0.996
1.0
62.8
131.6
113.4
158.6
89.4
124.9
References
1. Marsden, B.G., & Williams, G.V. 1995, Catalogue of Cometary Orbits, 10th ed., IAU Central Bureau for Astronomical
Telegrams and Minor Planets
2. Beatty, J.K., & Chaikin, A., editors. 1990, in The New Solar System (Sky Publishing, Cambridge), p. 292
Table 13.6. Outer solar system objects of probable cometary nature.a,b,c
Provisional
designation
Perihelion
(AU)
Aphelion
(AU)
a
e
i
H
D
(km)
1977 UB
1992 AD
1993 HA2
1994 TA
1995 DW2
1995 GO
1997 CU26
8.45
8.67
11.8
11.7
18.9
6.84
13.1
18.8
31.8
37.4
22.0
31.0
29.3
18.4
13.648
20.226
24.594
16.843
24.916
18.069
15.712
0.381
0.571
0.519
0.304
0.243
0.622
0.169
6.9
24.7
15.7
5.4
4.2
17.6
23.4
6.5
7.0
9.6
11.5
9.0
9.0
6.0
180
150
75
25
100
100
300
Trans-Neptunian Objects
1992 QB1
1993 FW
1993 RO
1993 RP
1993 SB
1993 SC
1994 ES2
1994 EV3
1994 GV9
1994 JQ1
1994 JR1
1994 JS
1994 JV
1994 TB
1994 TG
1994 TG2
1994 TH
1994 VK8
1995 DA2
1995 DB2
1995 DC2
1995 FB21
1995 GA7
1995 GJ
1995 GY7
1995 HM5
1995 KJ1
1995 KK1
40.9
41.5
31.5
34.9
26.9
32.3
40.3
40.8
41.0
41.8
34.8
33.0
35.3
27.1
42.3
42.4
40.9
41.7
33.7
40.1
40.8
42.4
34.8
39.0
41.3
29.5
43.5
32.0
47.7
45.5
47.7
43.8
52.4
47.5
50.8
44.7
46.0
46.1
44.1
51.6
35.3
52.6
42.3
42.4
40.9
44.0
38.7
52.5
46.9
42.4
44.2
46.8
41.3
49.3
43.5
47.0
44.298
43.522
39.608
39.329
39.633
39.880
45.530
42.763
43.495
43.959
39.434
42.289
35.251
39.845
42.254
42.448
40.940
42.830
36.181
46.290
43.850
42.426
39.455
42.907
41.347
39.369
43.468
39.475
0.077
0.045
0.205
0.114
0.321
0.191
0.115
0.046
0.058
0.049
0.119
0.219
0
0.321
0
0
0
0.027
0.069
0.134
0.070
0
0.119
0.091
0
0.251
0
0.190
2.2
7.8
3.7
2.6
1.9
5.1
1.1
1.7
0.6
3.8
3.8
14.1
18.1
12.1
6.8
2.2
16.1
1.5
6.6
4.1
2.3
0.7
3.5
22.9
0.9
4.8
2.7
9.3
7.0
7.0
8.0
9.0
8.0
7.0
7.5
7.0
7.0
7.0
7.5
8.0
7.0
7.0
7.0
7.0
7.0
6.5
8.0
7.5
7.0
7.5
7.5
7.0
7.5
8.0
6.5
8.5
250
250
150
100
150
250
200
250
250
250
200
150
250
250
250
250
250
300
150
200
250
200
200
250
200
150
300
125
Number
Centaurs
2060
5145
7066
Name
Chiron
Pholus
Nessus
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328 / 13
S OLAR S YSTEM S MALL B ODIES
Table 13.6. (Continued.)
Number
Name
Provisional
designation
Perihelion
(AU)
Aphelion
(AU)
a
e
i
H
D
(km)
1995 QY9
1995 QZ9
1995 WY2
1995 YY3
1996 KV1
1996 KW1
1996 KX1
1996 KY1
1996 RQ20
1996 RR20
1996 SZ4
1996 TK66
1996 TL66
1996 TO66
1996 TP66
1996 TQ66
1996 TR66
1996 TS66
1997 CQ29
1997 CR29
1997 CS29
1997 CT29
1997 CU29
1997 CV29
1997 CW29
1997 QH4
1997 QJ4
1997 RT5
1997 RX9
1997 RY6
1997 SZ10
1997 TX8
29.2
33.7
40.6
30.7
41.2
46.6
35.7
35.7
39.2
32.8
29.6
42.9
35.1
38.1
26.4
34.6
33.2
38.5
41.2
42.0
43.4
42.3
41.9
40.0
36.3
41.3
34.8
42.2
42.1
41.4
31.6
32.0
51.0
45.8
52.3
48.1
44.7
46.6
43.4
43.3
49.4
47.1
50.1
43.2
134.0
49.3
53.0
44.7
52.1
49.7
47.7
42.0
44.0
44.9
44.8
48.5
42.5
47.4
44.3
42.2
42.1
41.4
47.6
46.6
40.115
39.769
46.432
39.389
42.966
46.602
39.543
39.517
44.291
39.936
39.817
43.035
84.457
43.700
39.703
39.667
42.636
44.100
44.412
41.996
43.703
43.580
43.331
44.227
39.375
44.359
39.568
42.239
42.135
41.360
39.584
39.312
0.271
0.153
0.126
0.221
0.041
0
0.097
0.096
0.115
0.180
0.257
0.004
0.585
0.128
0.335
0.127
0.222
0.126
0.073
0
0.006
0.030
0.034
0.096
0.079
0.070
0.121
0
0
0
0.201
0.186
4.8
19.5
1.7
0.4
8.4
5.5
1.5
30.9
31.6
5.3
4.7
3.3
24.0
27.3
5.7
14.6
12.3
7.4
2.9
20.2
2.3
1.0
1.5
7.8
19.0
12.8
16.0
12.6
29.8
12.4
12.7
9.0
7.5
7.5
7.0
8.5
7.0
7.0
8.5
8.0
7.0
7.0
8.0
7.0
5.0
4.5
6.5
6.5
7.5
6.0
6.5
6.5
5.0
5.0
6.5
7.0
6.5
7.0
7.5
7.0
8.0
7.5
8.5
8.5
200
200
250
125
250
250
125
150
250
250
150
250
600
750
300
300
200
400
300
300
600
600
300
250
300
250
200
250
150
200
125
125
Notes
a IAU Minor Planet Center web page as of 1998, January 1. URL http://cfa.www.harvard.edu/cfa/ps/mpc.html.
b For explanation of symbols, see section on Minor Planets.
c Object 2060 Chiron is known to exhibit cometary activity, e.g., IAUC 4770 and is catalogued as comet 95P.
13.3
ZODIACAL LIGHT
The zodiacal light is due to sunlight scattered by the interplanetary dust cloud. Zodiacal light brightness
is a function of viewing direction, wavelength, heliocentric distance (r) and position of the observer
relative to the dust symmetry plane. The brightness does not vary with the solar cycle [9, 10]. A
comprehensive review is given in [11].
Table 13.7 presents the surface brightness (radiance) and degree of linear polarization of the
zodiacal light at λ5000 Å for an observer at r = 1 AU in the dust symmetry plane as a function of
helioecliptic longitude (λ − λ ) and latitude (β) [11–15].
Sp.-V/AQuan/1999/10/10:09:50
Page 329
13.3 Z ODIACAL L IGHT / 329
Table 13.7. Zodiacal light brightness and polarization.
β(◦ )
15
20
25
30
45
60
75
0
2450
.08
1260
.10
770
.11
500
.12
215
.16
117
.19
78
.20
5
2300
.09
1200
.10
740
.11
490
.12
212
.16
117
.19
78
.20
3700
.11
1930
.11
1070
.12
675
.13
460
.14
206
.17
116
.19
78
.20
λ − λ (◦ )
0
5
10
10
15
9000
.13
5300
.13
2690
.13
1450
.13
870
.13
590
.14
410
.15
196
.17
114
.19
78
.20
20
5000
.14
3500
.14
1880
.14
1100
.15
710
.15
495
.15
355
.15
185
.17
110
.19
77
.20
25
3000
.15
2210
.15
1350
.16
860
.16
585
.16
425
.16
320
.16
174
.18
106
.19
76
.20
30
1940
.16
1460
.16
955
.16
660
.16
480
.16
365
.17
285
.17
162
.18
102
.19
74
.20
35
1290
.17
990
.17
710
.17
530
.17
400
.17
310
.17
250
.17
151
.18
98
.20
73
.20
40
925
.17
735
.17
545
.17
415
.17
325
.18
264
.18
220
.18
140
.19
94
.20
72
.20
45
710
.18
570
.18
435
.18
345
.18
278
.18
228
.18
195
.18
130
.19
91
.20
70
.20
60
395
.19
345
.19
275
.19
228
.19
190
.19
163
.20
143
.20
105
.20
81
.20
67
.20
75
264
.18
248
.18
210
.18
177
.18
153
.18
134
.19
118
.19
91
.19
73
.19
64
.19
90
202
.16
196
.16
176
.16
151
.16
130
.16
115
.16
103
.17
81
.18
67
.18
62
.19
105
166
.12
164
.12
154
.12
133
.12
117
.13
104
.13
93
.14
75
.15
64
.17
60
.19
120
147
.08
145
.08
138
.09
120
.09
108
.09
98
.10
88
.11
70
.13
60
.15
58
.18
135
140
.05
139
.05
130
.05
115
.06
105
.06
95
.07
86
.08
70
.11
60
.14
57
.17
150
140
.02
139
.02
129
.02
116
.03
107
.03
99
.04
91
.05
75
.08
62
.12
56
.16
165
153
−.02
150
−.02
140
−.01
129
−.01
118
0
110
.02
102
.03
81
.07
64
.11
56
.16
180
180
0
166
−.02
152
−.03
139
−.02
127
−.01
116
0
105
.02
82
.06
65
.11
56
.16
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S OLAR S YSTEM S MALL B ODIES
The brightness is given in S10 (V), the equivalent number of tenth visual magnitude solar-type stars
per square degree. One S10 (V) = 1.26 × 10−8 W m−2 sr−1 µm−1 at 5000 Å. The uncertainty in
brightness and polarization is 10% in the bright regions, to 20% in the faint regions. Negative values
mean that the direction of polarization lies in the scattering plane. The brightness at the ecliptic pole
(β = 90◦ ) is 60 S10 (V) and the degree of linear polarization is 0.19 [11, 12].
The component of the solar corona due to scattering by interplanetary dust is known as the F corona.
The brightness of the solar F corona in S10 (V) is given in Table 13.8 as a function of elongation
() [16, 17], for the line of sight in the ecliptic plane (i = 0◦ ) and line of sight in a plane perpendicular
to the ecliptic plane (i = 90◦ ).
Table 13.8. Brightness of the solar F corona.
i = 0◦
i = 90◦
1◦
2
5
10
3.9 × 106
8.6 × 105
1.2 × 105
2.4 × 104
2.6 × 106
4.3 × 105
4.8 × 104
8300
UBV colors of the zodiacal light are given by [15]
IV
= 1.14 − 5.5 × 10−4 ,
IB
IB
= 1.11 − 5.0 × 10−4 ,
IU
where = solar elongation in degrees. An intensity ratio of 1.0 corresponds to solar color.
The dependence of intensity on heliocentric distance for an observer at r AU (0.3 ≤ r ≤ 1.0) as
measured from the Helios probe is [15]
I (r )
= r −2.3 .
I (1 AU)
The dependence of polarization on heliocentric distance [15] can be approximated by
P(r )
= r +0.3 .
P(1 AU)
For 1 < r < 3.3 AU, the I (r ) is given by
I (r )
= r −2.5±0.5 ,
I (1 AU)
as measured from Pioneer 10 [18].
The plane of symmetry of the zodiacal light deviates from the ecliptic by a few degrees, causing
annual variations of 10%–20% (peak to peak) in the zodiacal light brightness as viewed from Earth.
The symmetry plane differs in the inner and outer solar system; at r > 1 AU it is close to the invariant
plane
for r < 1 AU, i = 3◦.0 ± 0◦.3,
for r ≥ 1 AU,
i = 1◦.5 ± 0◦.4,
= 87◦ ± 4◦ ,
[19],
= 96◦ ± 15◦ ,
[9],
where i = inclination to the ecliptic and = ecliptic longitude of the ascending node.
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13.4 I NFRARED Z ODIACAL E MISSION / 331
Figure 13.1. Zodiacal emission (radiance) as a function of solar elongation in the ecliptic plane [20]. : 10.9 µm;
: 20.9 µm.
13.4
INFRARED ZODIACAL EMISSION
At λ 3 µm, thermal emission from the interplanetary dust (zodiacal emission, or ZE) dominates
over scattered light. The zodiacal emission at 1 AU has been measured from rockets [20], from the
Infrared Astronomical Satellite (IRAS) [21, 22], and from the Diffuse Infrared Background Experiment
(DIRBE) on the Cosmic Background Explorer (COBE) satellite [23].
The observed variation in the 10.9 µm and 20.9 µm radiance along the ecliptic plane is presented in
Figure 13.1 [20]. Absolute calibration accuracy is approximately 20%. Model fits for assumed radial
dust distribution ∝ r −1.3 and r −1.0 are shown by the dashed and solid lines.
Figure 13.2 shows the variation of zodiacal emission with ecliptic latitude at or near = 90◦ (i.e.,
in a plane perpendicular to the Earth–Sun line) as determined from survey observations of the IRAS
satellite between February and November 1983 [21, 24]. Only the smooth component of the ZE is
shown, represented by the following slowly-varying empirical function [25]. To remove zodiacal dust
bands [22], point sources, and the diffuse emission of the Galaxy, the function was fitted in a lower
envelope sense to IRAS scans that extended nearly from one ecliptic pole to the other:
I (β) = I0 − δ I {1 − δβ | cosec(β) | [1 − exp(−β/δβ − (β/δβ)2 /3)]},
where
I (β) = brightness at ecliptic latitude β,
β = geocentric ecliptic latitude,
I0 = peak brightness,
δ I = parameter with units of brightness, and
δβ = angle parameter characterizing the width of the brightness distribution.
The parameter values shown in Table 13.9 represent an annual average of the ZE at = 90◦ .
The position of peak emission deviates sinusoidally from the ecliptic plane by about two degrees on
Sp.-V/AQuan/1999/10/10:09:50
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S OLAR S YSTEM S MALL B ODIES
Figure 13.2. Intensity of the smooth component of the zodiacal emission as a function of the ecliptic latitude at
solar elongation 90 ◦ : annual average from IRAS data [25].
a yearly cycle owing to the Earth’s orbital motion in a plane inclined with respect to the approximate
symmetry plane of the interplanetary dust; the peak brightness of the ZE near the ecliptic plane, I0 , and
the ecliptic pole brightness, given by I0 − δ I (1 − δβ), similarly vary modestly on an annual cycle [25].
Table 13.9. Empirical function parameters for the ZE at = 90◦ .
Wavelength
Fitted parameter
12 µm
25 µm
60 µm
I0 (MJy sr−1 )
δ I (MJy sr−1 )
δβ (degrees)
37
34
15.6
77
70
14.0
31
29
12.0
At 12 and 25 µm the diffuse infrared emission of the sky is dominated by zodiacal emission; at
60 µm, the ZE becomes less prominent, and by 100 µm emission from the galactic plane dominates
the appearance of the sky, and the ZE is too weak compared with emission from the Galaxy to permit
reliable separation by this method.
A linear transformation converts the IRAS values in Table 13.9 and Figure 13.2 to the somewhat
different DIRBE calibration to an rms accuracy of several percent [26]. (Unlike IRAS, DIRBE has an
instrumentally established zero point, an ability to measure electrical and radiative offsets, and superior
stray light rejection.) The transformation is given as
(DIRBE value) = Gain × (IRAS value) + Offset,
where, at 12, 25, and 60 µm, respectively, Gain = 1.06, 1.01, and 0.87, and Offset = −0.48, −1.32,
and 0.13 MJy sr−1 .
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13.5 M ETEOROIDS AND I NTERPLANETARY D UST / 333
13.5
METEOROIDS AND INTERPLANETARY DUST
This section deals with the characteristics of meteoroids and interplanetary dust as determined from
studies of their ablation or collection in the Earth’s atmosphere, and from detections of impacts on
spacecraft. The remote sensing of the space dust population through observations of the zodiacal light,
or infrared studies such as from IRAS, COBE, ISO, etc., are covered in the preceding section.
Solid particles in space smaller than about 10 m in size are termed meteoroids, larger bodies being
asteroids. Meteoroids produce meteors (synonym shooting star) when they enter the atmosphere.
The term “meteor” encompasses the atmospheric phenomena resulting (optical emission, train of
ionization, etc.). Dependent upon composition, entry angle, speed, and density, particles smaller than
about 100 µm in size do not ablate, but remain intact and gradually settle to the Earth’s surface. These
particles are termed interplanetary dust. Such a size limit is also convenient because the majority of
the zodiacal light is the result of scattering by particles in the 10–100 µm range.
The absolute visual magnitude of a meteor (M) is the observed magnitude corrected to a standard
height of 100 km at the observer’s zenith. Meteor activity (i.e., detection rate) is normally expressed
in terms of the zenithal hourly rate. Sporadic (nonshower) activity is of the order of 5–10 per hour
to M = 6.5, although there is a seasonal variation which depends upon the solar longitude and the
observer’s latitude. Meteor shower activity may be detectable at rates as low as a few per hour, although
most well-known showers have zenithal rates of order 20–50 per hour. The prominent meteor showers,
occurring when the Earth passes through a meteoroid stream, are listed in Tables 13.10 and 13.11.
Every so often an exceptional shower will occur, with rates up to many thousands per hour being seen.
At the time of writing the next such events, termed meteor storms, are anticipated in 1998 and/or 1999
November when the Leonid storm is due. For a more extensive discussion of all of the above, see [27].
Table 13.10. Principal meteor showers.a
Radiant
Shower nameb
Quadrantids
Lyridsg
η Aquarids
Arietidsh
ζ Perseidsh
β Tauridsh
α Capricornids
S δ Aquarids
Perseidsi
κ Cygnids
S Taurids
N Taurids
Orionids
Draconids j
Leonidsk
Geminids
Ursidsl
Diurnal drift
Activity period
Solar long.c
RA
Dec
RA
Dec
Local time
of transit
Vgd
re
Peak
ZHR
Number
density f
Jan 01–05
Apr 16–25
Apr 19–May 28
May 29–Jun 19
Jun 01–17
Jun 07–Jul 07
Jul 03–Aug 19
Jul 15–Aug 28
Jul 17–Aug 24
Aug 03–31
Sep 15–Nov 25
Sep 15–Nov 25
Oct 02–Nov 07
Oct 06–10
Nov 14–21
Dec 07–17
Dec 17–26
283.3
32.1
43.1
77
77
97
127
126
139.9
146
221
231
208
197.0
235.2
262.0
270.9
230
271
336
44
62
86
307
339
46
286
50
60
95
262
152
112
217
+49
+34
−02
+23
+23
+19
−10
−16
+58
+59
+14
+23
+16
+54
+22
+33
+75
+0.4
+1.1
+0.9
+0.7
+1.1
+0.8
+0.9
+0.7
+1.3
+0.3
+0.8
+0.9
+0.7
+0.4
+0.7
+1.0
0
−0.2
0.0
+0.4
+0.6
+0.4
+0.4
+0.3
+0.2
+0.1
+0.1
+0.2
+0.2
+0.1
0
−0.4
−0.1
0
08.5
04.0
07.6
09.9
11.0
11.2
00.0
02.2
05.7
21.3
00.5
00.5
04.3
16.1
06.4
01.9
08.4
39
48
65
35
25
28
20
39
58
22
25
27
65
17
70
33
31
2.2
2.9
2.7
—
—
—
2.5
3.2
2.6
3.0
2.3
2.3
2.9
2.6
2.5
2.6
3.0
120
20
50
—
—
—
10
20
100
5
10
8
25
—
25
110
20
80
8–10
4–5
—
—
—
150
20–25
10–20
125
50
30
2
—
1–2
290
80
Notes
a Courtesy J. Rendtel, M. Gyssens, P. Roggemans, and P. Brown, International Meteor Organization. All angles are in
degrees, and referred to the 1950.0 equinox.
b See Table 13.11 for parent comet identifications.
c The solar longitude is that at the time of peak shower activity.
d V is the geocentric velocity of the meteoroid; the velocity at the top of the atmosphere after acceleration by the Earth is
g
given by V 2 = Vg2 + 125 (in km/s).
e The mass index s is related to the population index r by s = 1 + 2.3 log r (see [1] for details).
10
f The number density gives the number of particles of m > 10−3 g per 109 km3 [2].
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S OLAR S YSTEM S MALL B ODIES
g ZHR to 90.
h Daytime showers.
i ZHR > 200 in 1992–94 near parent comet return.
j Also known as the Giacobinids; periodic shower with ZHR > 200 occurring near alternate parent comet returns.
k Meteor storms anticipated in 1998 and 1999 near parent comet return with ZHR > 1000.
l ZHR to 50.
References
1. Hughes, D.W. 1978, in Cosmic Dust, edited by J.A.M. McDonnell (Wiley, New York), p. 123
2. Hughes, D.W. 1987, A&A, 187, 879
Table 13.11. Orbits of meteoroid streams [1].
Shower name
(AU)
eb
qc
(AU)
ωd
(◦ )
e
(◦ )
if
(◦ )
Quadrantids
Lyrids
η Aquarids
Arietids
ζ Perseids
β Taurids
α Capricornids
S δ Aquarids
Perseids
κ Cygnids
S Taurids
N Taurids
Orionids
Draconids
Leonids
Geminids
Ursids
3.08
28
13
1.6
1.6
2.2
2.53
2.86
28
3.09
1.93
2.59
15
3.51
11.5
1.36
5.70
0.683
0.968
0.958
0.94
0.79
0.85
0.77
0.976
0.965
0.68
0.806
0.861
0.962
0.717
0.915
0.896
0.85
0.977
0.919
0.560
0.09
0.34
0.34
0.59
0.069
0.953
0.99
0.375
0.359
0.571
0.996
0.985
0.142
0.939
170
214
95
29
59
246
269
153
152
194
113
292
83
172
173
324
206
283.3
32.1
43.1
77
77
277
127
306
139.9
146
41
231
28
197.0
235.2
262.0
270.9
72.5
79
163.5
21
0
6
7
27.2
113.8
38
5.2
2.4
163.9
30.7
162.6
23.6
53.6
aa
Parent objects
96P/Machholz 1 & 1491 I?
C/Thatcher (1861 G1)
1P/Halley
96P/Machholz 1 & 1491 I?
2P/Encke & various asteroids
—
—
96P/Machholz 1 & 1491 I?
109P/Swift–Tuttle
—
2P/Encke & various asteroids
1P/Halley
21P/Giacobini–Zinner
55P/Tempel–Tuttle
(3200) Phaethon
8P/Tuttle
Notes
a a is the semimajor axis.
b e is the orbital eccentricity.
c q is the perihelion distance, q = a(1 − e).
d ω is the argument of perihelion.
e is the longitude of the ascending node (equinox 1950.0).
f i is the inclination to the ecliptic.
Reference
1. Cook, A.F. 1973, in Evolutionary and Physical Properties of Meteoroids, NASA SP-319, edited by C.L.
Hemenway and A.F. Cook (NASA, Washington, DC)
The above discussion pertains to visual meteors, mostly produced by meteoroids larger than ∼ 1 cm
in size. Fainter meteors may be detected through HF/VHF radio wave scattering from their trains of
ionization [27, 28]. Such meteors are due to smaller meteoroids, typically 100 µm–1 mm in size.
The limiting magnitude is about +15 (corresponding to the micrometeor limit at ∼ 100 µm); radars
sensitive to such magnitudes may detect meteors at rates of one per few seconds, and especially
powerful radars covering large areas at rates exceeding one per second [29]. It was thought for some
years (see [27]) that the deficit of meteors detected in the radar regime (masses 10−6 –10−2 g) was due
to the reduced ionizing efficiency of low-speed meteoroids (that efficiency varies as ∼ V 3.5−4.0 , V
being the top-of-the-atmosphere velocity), but it is now known that the finite “echo ceiling” [28] of
HF/VHF radars has led to only those ablating lower than ∼ 105 km being detected, meaning that the
majority ablating higher have been missed, but are detectable using MF radars [29, 30].
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13.5 M ETEOROIDS AND I NTERPLANETARY D UST / 335
The magnitude of a meteor is given in [27, 28]:
M = 40 − 2.5 log10 αz ,
where αz is the zenithal electron line density (per meter) in the train.
There have been many determinations of the relationship between αz , V , and the initial meteoroid
mass m [27, 31], both from theory and from observations. The form of the expression is generally
given as
αz = C 1 m x V y
(m−1 ),
where the normalizing constant C1 has values typically in the range 2–8 × 10−10 , x = 0.9–1.1, and
y = 3.2–4.0. Dependent upon the velocity, one finds [27]:
log10 αz = C2 + log10 m,
where C2 = 16–17. This implies that a meteor of zenithal magnitude zero (M = 0) has a mass of
∼ 0.1–1 g.
The above assumed that the mean sporadic meteoroid speed is ∼ 30–40 km/s; in fact the initial
analysis of the Harvard Radar Meteor Project results [32] implied that the mean speed, at least for
faint radar meteors, is < 20 km/s, but apparently an error was made such that the real mean speed is
somewhat higher than 20 km s−1 [33]. Particles arriving from heliocentric elliptical orbits may impact
the Earth at speeds between 11 and 73 km/s.
The composition of meteoroids and dust is still a matter of uncertainty. Spectroscopic observations
of meteors indicate highly differentiated material similar to various meteorite classes, whilst dust
collection in the stratosphere also indicates compositions similar to meteorite classes although volatile
components may have been lost through heating in atmospheric entry; hypervelocity spacecraft impacts
are unlikely to leave traces of any but the most refractory components. A variety of recent papers
on these topics, and other features of meteoroids and interplanetary dust, may be found in [34–39].
The present state of knowledge indicates that the particles under consideration are largely comprised
of meteoritic-type materials (silicates, nickel–iron) but with a significant fraction of heavy organics
(kerogens) that are thermodynamically stable over periods of ∼ 104 yr after release from their parent
bodies, but which are destroyed on atmospheric entry.
The origin of at least some meteoroids is indicated by the association of various meteor showers
with specific comets through orbit similarity [40]. The orbits of meteoroids determined in various
surveys are reviewed and cataloged in [41], where evidence linking showers with various Earthcrossing asteroids (see Table 13.11) is also discussed. Larger meteoroids in the 5–10 m size range
may also be cometary fragments [42]. While many meteoroids appear to be of low density (ρ <
1 g/cm3 ), there is also a high-density component with ρ = 3–8 g/cm3 [43], [44]. The evolution of
meteoroid streams is reviewed in [45]. The origin of sporadic meteors appears to be gravitational
stirring of streams, in particular by Jupiter; small meteoroids and dust are also subject to orbital
circularization/inspiralling toward the Sun under the influence of the Poynting–Robertson drag force,
with various other effects also being significant.
Meteoroids tend to end their lives through impacts upon smaller dust particles, their comminution
maintaining the interplanetary dust supply (although it is not clear whether the present complex is in
balance [46]), which in turn is depleted through collisions, inspiralling, and eventual ejection from the
solar system by radiation/solar wind pressure.
The terrestrial mass accretion rate of small meteoroids and dust has been established from impact
data collected with the Long Duration Exposure Facility [47] and other satellites [48], the small particle
influx being 40 ± 20 × 106 kg per year (see Figure 13.3), in accord with the influx determined by radar
Sp.-V/AQuan/1999/10/10:09:50
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S OLAR S YSTEM S MALL B ODIES
Figure 13.3. The logarithmic incremental mass influx to the Earth, in units of 106 kg per year per logarithmic
mass interval. For these small particles (meteoroids and dust) the peak influx is at ∼ 10−5 g, and the integral under
this curve is ∼ 40, 000 tonnes/year [47], although larger particles (asteroids and comets) dominate the long-term
averaged mass influx [50]. From [47], Figure 4.
meteor techniques [29]. The small particle influx can also be measured from ice cores [49]. The influx
over the whole mass spectrum (from dust through to large asteroids and comets) is reviewed in [50].
Whilst the interplanetary complex of meteoroids and dust is significant in a number of ways (such as
its effect upon atmospheric chemistry and the light it scatters producing a diffuse background), its total
mass is only equivalent to an asteroid or comet a few tens of kilometers in diameter.
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