Geoscience Reference
In-Depth Information
where
m
∆
=
m
1
−
5 log ∆ is heliocentric magnitude of comet,
m
1
is comet's
observed integrated magnitude,
H
0
is absolute magnitude of comet,
n
is
photometrical exponent, ∆ and
r
are the geocentric and the heliocentric
distances of comet, respectively.
An absolute magnitude
H
10
, which had been introduced by
S. Vsekhsvyatsky, is important for the study of the secular evolution of
cometary activity. This parameter is represented by the equation
H
10
=
m
1
−
5log∆
−
10 log
r.
(2)
3. Visual Brightness Behavior
The light curve of visual integrated brightness of comets characterizes the
change of their activity with time and with heliocentric distance. The com-
parison of light curves of short-period comets in their different returns gives
the information about the evolution of cometary activity and on the rela-
tion between cometary brightness behavior, solar activity, and condition in
the interplanetary space.
3.1.
Light curves
The brightness behavior of comet 9P/Tempel 1 before perihelion was sim-
ilar during all four returns (see Fig. 1). As it can be seen, the peaks on
brightness (associated to comet outbursts) occur at equal about similar
heliocentric distances in all returns. Especially it can be clearly seen that
the outbursts occurred on distances 1.8, 1.76, 1.62, and 1.51 AU from Sun
[log(
r
)=0
.
255, 0.246, 0.210, and 0.179 accordingly]. Authors have found
10
12
14
16
18
20
22
1972
1983
1994
2005
0.15
0.18
0.21
0.24
0.27
0.3
log (
r
)
Fig. 1. The light curves of comet 9P/Tempel 1 in four returns. For a better display
m
∆
has been displaced by 4
m
for 1983, 7
m
for 1994, and 9
m
for 2005.
