The moon of Jupiter – S/2000
J11 – was discovered in late November 2000
by the following team of astronomers: S.S. Sheppard
,
D.C. Jewitt
,
Y. Fernandez
and G. Magnier
. This discovery was achieved by
2.2-m telescope atop Mauna Kea (Hawaii).
S/2000 J11 is one of eleven new satellites new satellites discovered since the
→Voyager-2
Jupiter system fly-by which occured 21 years ago (1979). With this moon, the team discovered also: Themisto, Kalyke,
Iocaste, Erinome, Harpalyke,
Isonoe, Praxidike,
Megaclite, Taygete and Chaldene.
The moon is in elliptical prograde orbit (→eccentricity
e = 0.2480) with a →semimajor axis a = 12,555,000 km. At pericenter (closest to the planet) S/2000 J11 is separated from the Jupiter a distance of q = 9,441,360 km. At apocenter (furthest from the planet) this moon is separated from the Jupiter a distance of Q = 15,668,640 km.
In future these parameters may vary due to a large orbital distance from Jupiter and the orbital motion being disturbed by the Sun and other factors. Perhaps it is a captured asteroid,
and in future will possibly return to heliocentric orbit.
An in teresting feature of that
moon is that being the in nermost ''irregular'' satellite of Jupiter (in
a higly inclined elliptical orbit), it revolves in the same direction as the
planet is spinning on its axis. Due to its similarity in semimajor axis to some
of the other satellites of Jupiter, it is considered to be a member of a so
called Himalia (probably the remnants of a single
large body). It is in teresting to note that it remains the only one of the eleven moons discovered in 2000 that has not yet been given a name while
the →IAU
has already named even those discovered in 2001! And so far giving names to Jupiter's satellites has proven not to be very difficult due to Zeus' notorious adultery
– he was cheating on Hera with countless lovers :)
The orbital period is over
2/3 earthly year, which means that the average speed of its celestial motion is
only 1°15'16'' per day. When this motion was detected and compared to the changes in Jupiter's position, this body was classified as a true planetary satellite (and not a distant celestial body with its position projected near the planet).
Other obstacle in detecting this moon earlier was its brightness of only 22.4m
(over 3.6 million times fainter than the faintest stars visible to naked eye). For comparison: Jupiter's brightness is about –2.7m,
so S/2000 J11 is shining fainter by about 25.1m.
The corresponding difference in brightness is almost 11 billion times!
I have given some crucial data of S/2000 J11 below. Table one contains the basic
information. Whereas table two gives more detailed parametrs of its orbit (calculated using the following formulae).
Translated by Karol Pankowski
|
S/2000 J11
|
|---|
| Mean distance from the planet [×103 km] |
12,555.0
|
| Mean distance from the planet [planetary R] |
175.6
|
| Orbital period [days] |
287.00
|
| Orbital eccentricity [e] |
0.2480
|
| Orbit inclination [degrees] |
28.3
|
| Mean diameter [km] |
4.0
|
| Main discoverer and year of the discovery |
S.S. Sheppard 2000
|
| Visual magnitude [mag] |
22.4
|
| Mass [kg] |
?
|
Orbital Parameters |
Pericenter [q] |
Apocenter [Q] |
| Distance from the planet [×103 km] |
9,441.4
|
15,668.6
|
| Distance from the planet [planetary R] |
132.1
|
219.2
|
| Angular size of the moon's orbit observed from the Earth* [degrees] |
0°51'37.36''
|
1°25'40.63''
|
|
| Angular diameter of the planet's disc as observed from the moon [degrees] |
0°52'03.79''
|
0°31'22.27''
|
| Brightness of the planet as observed from the moon** [mag] |
–11.8
|
–10.7
|
| Diameter of the moon's disc as observed from the planet's "surface" [degrees] |
0°00'00.09''
|
0°00'00.05''
|
| Brightness of the moon as observed from the planet's "surface"** [mag] |
13.3
|
14.4
|
|
Orbital velocity [km/sec] |
4.09
|
2.47
|
* This value is calculated for Jupiter at opposition (distance 628.8 million km = 4.2 AU)
** The given value of magnitude is not corrected for some decreasing factors (e.g. the changing phase of illumination)
|
See other related links:
Monde
des Monats
– HIMALIAGRUPPE
Jupiter's New Satellites
The Astronomy Workshop
– Satellite Viewer
Planetary Satellite Mean Orbital Parameters
Natural Satellite Physical Parameters