[meteorite-list] Twelve New Satellites of Saturn Discovered

[Ron Baalke]

http://www.ifa.hawaii.edu/~jewitt/saturn2005.html

TWELVE NEW MOONS FOR SATURN 
David Jewitt
May 3, 2005

SUMMARY

Minor Planet Electronic Circular MPEC J13 today reports the discovery of
12 previously unknown satellites of Saturn, doubling the number of known
irregular satellites and bringing the total number of moons of that
planet to 46. The discoveries were made as part of a long-term and
highly productive program to explore the planetary satellite systems
using the world's largest telescopes atop Mauna Kea, Hawaii.

DETAILS

The satellites were discovered on December 12, 2004 using the wide-field
SuprimeCam camera on the 8.2-meter diameter Subaru telescope on
Mauna Kea. They were followed up in January, February and March 2005
using Subaru and the nearby 8-m diameter Gemini North
telescope [see Sample Images <http://www.ifa.hawaii.edu/~jewitt/satsatimages.html>]

The satellites were formally announced by the International Astronomical
Union on May 3, 2005. The orbital elements are given in Table 1
<http://www.ifa.hawaii.edu/~jewitt/elements.jpg>. All but one (S/2004
S11) orbit Saturn in a direction opposite to the planet's spin. These
retrograde orbits are a hallmark of an origin by capture. The new moons
range in diameter from about 3 km to 7 km, assuming a surface albedo of 4%.

<http://www.ifa.hawaii.edu/faculty/jewitt/2004s11movie-1.gif>

Figure 1: New irregular satellite S/2004 S11 is located in the center of
this 3-image blink sequence from the Subaru telescope. The satellite
moves nearly vertically in these images (West is to the top, North to
the right), which are separated in time by about 1/2 hour. Background
stars and galaxies remain fixed. Objects which appear in only one image
are cosmic ray hits, noise spikes and/or image defects. Click the image
for a larger view. If you can't find the satellite, here's a cheat
<http://www.ifa.hawaii.edu/~jewitt/satsatimages.html>.

SCIENCE

These new discoveries improve our knowledge of the satellite system and
should, eventually, lead to an understanding of the origin
of the irregular satellites. Already we have found that the most 
studied capture model <http://www.ifa.hawaii.edu/~jewitt/capture.html> 
is unable to explain the systematics of the irregular satellite 
populations. Most surprisingly, we have found that the four giant 
planets all possess about the same number of irregular satellites when 
measured down to a given size, independent of planet mass, location, or 
formation mode.  This observation remains unexplained.

THE FACILITIES

# SUBARU OBSERVATORY <http://www.naoj.org/>
# GEMINI OBSERVATORY <http://www.gemini.edu/>

RELATED LINKS

# Hawaii Irregular Satellites Page
<http://www.ifa.hawaii.edu/faculty/jewitt/irregulars.html>
# Scott's Saturn Satellite Page
<http://www.ifa.hawaii.edu/~sheppard/satellites/satsatdata.html>

CONTACTS

# David Jewitt, University of Hawaii, jewitt at ifa.hawaii.edu,
phone 808 956 7682
# Scott Sheppard, Dept. Terrestrial Magnetism, Carnegie 
Institute of Washington, sheppard at dtm.ciw.edu, phone 202 478 8854
# Jan Kleyna, University of Hawaii
# Brian Marsden, Harvard-Smithsonian Center for Astrophysics