J/A+A/295/206 Meteor stream activity. II. (Jenniskens, 1995)
Meteor stream activity. II. Meteor outbursts
Jenniskens P.
<Astron. Astrophys. 295, 206 (1995)>
=1995A&A...295..206J 1995A&A...295..206J (SIMBAD/NED Reference)
ADC_Keywords: Minor planets
Keywords: meteors: meteoroids
Description:
In the past two centuries, alert amateur and professional meteor
astronomers have documented 35 outbursts of 17 individual meteor
streams well enough to allow the construction of a homogeneous set of
activity curves. These curves add to similar profiles of the annual
streams in a previous paper (Paper I, See Cat. J/A+A/287/990).
The activity curves, expressed in terms of Zenith Hourly Rates (ZHR),
have a shape that is usually well described by:
ZHR=ZHR(max)10^(-B|λ_{sun }-{lambda☉_(max)}|)^. The
steepness of the slopes varies from an exponent of B=7 to B=220 per
degree of solar longitude, with a typical value of B=30.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1a.dat 94 49 Catalogue of meteor outburst events that
occurred between 1793 and 1993
table1b.dat 118 49 Parameters that describe the main peak in the
activity curve
table1c.dat 80 12 Parameters that describe the background
component in the activity curve
--------------------------------------------------------------------------------
See also:
J/A+A/287/990 : Meteor stream activity I. (Jenniskens 1994)
Byte-by-byte Description of file: table1a.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- ComType Comet type (1)
5- 7 A3 --- Code Name of the stream in a three letter code
9- 28 A20 --- Name Common name
30- 42 A13 --- Date Date of maximum activity
44- 48 F5.1 deg RAdeg ? True radiant position in equinox 1950.0,
corrected for zenith attraction
(Earth's gravitational pull)
50- 54 F5.1 deg DEdeg ? True radiant position in equinox 1950.0,
corrected for zenith attraction
(Earth's gravitational pull)
55 A1 --- u_RAdeg [)] Uncertainty flag on radiant position
56 A1 --- n_RAdeg [*] Note on radiant position
57 A1 --- l_Vinf [~] Limit flag on Vinf
58- 59 I2 km/s Vinf Apparent entry velocity, which is the
geocentric entry velocity to which is added
the component due to the Earth's
gravitational pull:
Vinf = sqrt(V_G2 + 11.22) km/s
61- 62 A2 --- l_Chi [=≳ ] Limit flag on Chi
63- 65 F3.1 --- Chi ? Magnitude distribution index,
Chi = n(M+1)/n(M).
68- 69 I2 --- Nobs1 ? Number of people who observed the event
70 A1 --- n_Nobs1 [mrs] Note when Nobs1 is not detailed
m: many, r: radar, s: several
72 I1 --- Nobs2 ? Number of reports that are useful for
evaluating the activity profile
74- 80 F7.1 --- E-C ? Time in days or years that the Earth
follows (+) or leads (-) the comet at
passing the node
82 A1 --- x_E-C [dy] Units in which E-C is expressed,
d = days, y = years
84- 91 F8.5 --- DE-C ? Minimum distance that the comet passes
outside (+) or inside (-) the Earth's orbit
93- 94 I2 --- ID Catalogue entry number
--------------------------------------------------------------------------------
Note (1): nc: near-comet type
fc: far-comet type
u: unknown type
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1b.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- ComType Comet type (1)
5- 6 I2 -- ID Catalogue entry number
9- 11 A3 --- Code Coded name
13- 16 I4 yr Year Year of the event
18- 19 A2 --- l_lomax [<≥∼ ] limit flag on lomax
20- 26 F7.3 deg lomax ? Peak position in terms of solar
longitude (Eq. 1950.0)
27 A1 --- n_lomax [)T?] When 'T' the data are in table1c
29- 30 A2 --- l_ZHRmax [≥∼ ] Limit flag on ZHRmax
31- 35 I5 h-1 ZHRmax ? Peak rate (meteors per hour)
36 A1 --- n_ZHRmax [l?] 'l' means 'like rain'
39- 42 I4 h-1 e_ZHRmax ? rms uncertainty on ZHRmax
43 A1 --- u_ZHRmax [)] Uncertainty flag on ZHRmax
45- 46 A2 --- l_Bp [≥≲ ] Limit flag on Bp
47- 51 F5.1 deg-1 Bp ? Slope of ascending (B+) and
descending (B-) branches
52 A1 --- n_Bp [-] A '-' indicates an interval for Bp
53- 54 I2 deg-1 Bp2 ? Highest value of Bp when n_Bp = '-'
55- 58 F4.1 deg-1 e_Bp ? rms uncertainty on Bp
60- 61 A2 --- l_dE-C [<≥∼ ] Limit flag on dE-C
62- 67 F6.3 deg dE-C ? Difference between time of maximum
activity and the node of the comet
dE-C=lomax/Omega_c (or between maximum
activity and point of closest approach
when n_dE-C = 1 )
68 A1 --- u_dE-C [)] Uncertainty flag on dE-C
69 I1 --- n_dE-C [1]? When 'n_dE-C' = 1, dE-C is the
difference between maximum activity
and point of closest approach
70 A1 --- l_Pc [~] Limit flag on Pc
71- 77 F7.2 yr Pc ? Orbital period of the comet
78 A1 --- n_Pc [i] When 'i', the orbital period of the
comet is infinity
79- 82 F4.2 AU q ? Perihelion distance (2)
85- 87 I3 deg i ? Inclination of orbit (2)
90- 92 I3 deg w ? Argument of perihelion (2)
95- 99 F5.2 g M0 ? Mass of a zero magnitude meteor
100 A1 --- l_rho [~] Limit flag on 10-24rho
101-107 F7.1 10-24g/cm3 rho ? Density of matter in the peak of the
meteoroid stream. (10-24rho)
109 A1 --- l_Mtot [~] Limit flag on Mtot
110-117 F8.6 10+15g Mtot ? Total mass in the stream. I assume
cylindrical geometry. Masses are taken
to be a factor less than this for
near-comet type outbursts, where
matter is concentrated near the
comet's position.
118 A1 --- u_Mtot [)] Uncertainty flag on Mtot
--------------------------------------------------------------------------------
Note (1): nc: near-comet type
fc: far-comet type
u: unknown type
Note (2): For meteoroids to cross the orbit of the Earth, orbital elements
are related according to: a(1-e2) = 1 ± e cos(w).
where e = 1-q/a is the eccentricity of the orbit.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1c.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- ComType Comet type (1)
5- 6 I2 --- ID Identification number
9- 11 A3 --- Code Coded name
13- 16 I4 yr Year Year of observation
19- 25 F7.3 deg lomax Peak position in terms of solar
longitude (Eq. 1950.0)
26 A1 --- u_lomax [)] Uncertainty flag on lomax
27 A1 --- l_ZHRmax [~] Limit flag on ZHRmax
28- 33 F6.1 h-1 ZHRmax Peak rate (meteors per hour)
35- 36 I2 h-1 e_ZHRmax ? rms uncertainty on ZHRmax
37 A1 --- u_ZHRmax [)] Uncertainty flag on ZHRmax
39 A1 --- l_Bb+ [~] Limit flag on Bb+
40- 43 F4.2 deg-1 Bb+ ? Slope of ascending branches
45- 47 F3.1 deg-1 e_Bb+ ? rms uncertainty on Bb+
51 A1 --- l_Bb- [~] Limit flag on Bb-
52- 54 F3.1 deg-1 Bb- ? Slope of descending branches
56- 58 F3.1 deg-1 e_Bb- ? rms uncertainty on Bb-
60- 65 F6.4 10+15g Mb ? Mass of the background
67- 71 F5.1 --- Mb/Mp ? Ratio of mass in the background component
relative to the main peak
75- 80 F6.4 10+15g Mtot ? Sum of mass estimates of background and
main peak
--------------------------------------------------------------------------------
Note (1): nc: near-comet type
fc: far-comet type
u: unknown type
--------------------------------------------------------------------------------
(End) Patricia Bauer [CDS] 04-Nov-1994