January 2001 TOPS Newsletter
Hau`oli Makahiki Hou, TOPS Participants!
TOPS 2001 ApplicationsTeachers, if you have friends who would like to attend TOPS 2001, please have them contact Bev immediately. We are still looking for some high quality applicants. We are reviewing applications as quickly as possible (a lengthy task with the number of student applicants we 've had) and hope to notify all applicants of their status later this week.
Party TimeYou, your friends, and your families are invited to our next TOPS star party on February 17 from 5:00 - 9:00 pm at Dillingham Field. We' ll begin with a potluck at 5:00. Please RSVP to Mary at email@example.com if you plan to come.
TOPS 2001 ScheduleIf you have any suggestions for the workshop schedule of classes and activities, please send your comments to Bev by January 31. We are working on the final schedule for the 2001 workshop.
UH College CreditsIf you received an Incomplete grade, Karen will submit your new grade later this semester. You won't hear from the university about your new grade until the end of the spring semester, when they process all the grades at once. An Incomplete does not reflect badly on you. In nearly every case, it just means that you are carrying out your follow-up workshops and other activities in the spring semester instead of the fall. This is fine with us but confusing to the university. TOPS just doesn't fit the normal class schedule.
Great Accomplishments!Caleb Parson is Teacher of the Year at Rota High School. Congratulations, Caleb. If any of you other teachers or students win awards or honors, please send the news to Bev. We would like to boast about you in this newsletter.
Forrest Luke Needs HelpFor those of you on Oahu, here are some events you might enjoy, and you can help Forrest, our most faithful TOPS volunteer, at the same time. In addition to volunteering at TOPS, Forrest also conducts star parties for schools and other organizations. He needs help on the following dates:
Eleven New Moons of JupiterIFA astronomers, including some guest faculty members at TOPS, have discovered new moons around Jupiter. You can get more information at the Web site, http://www.ifa.hawaii.edu/faculty/jewitt/jmoons/jmoons.html. Following is the press release that summarizes the discovery.
University of Hawaii Institute for Astronomy scientists report their discovery of 11 new satellites of Jupiter, all members of Jupiter's outer "irregular" satellite system. These observations double the number of such moons known to orbit the planet and are the largest number of satellites ever discovered at one time. Ten of the discoveries were announced on January 5 on International Astronomical Union Circular IAUC 7555. The 11th was announced at the end of November on IAUC 7525.
The satellites were discovered during a systematic search of the space near Jupiter conducted at the University of Hawaii 88 inch (2.2 meter) telescope atop Mauna Kea. The team, lead by IfA graduate student Scott Sheppard and Professor David Jewitt, and aided by Drs. Yan Fernandez and Eugene Magnier, used a large format charge-coupled device (CCD) camera (the "8K") to obtain a wide field of view. The CCD produces digital images that can be conveniently analyzed using computers. The observing strategy was to obtain 3 images of each position in order to search for objects moving against the star and galaxy background. Objects near Jupiter move with a characteristic slow speed that helps us to distinguish them from foreground asteroids and background Kuiper Belt Objects.
One of the 11 new satellites turns out to have been a previously observed but long-lost object S/2000 J1. The other 10 have not been previously seen.
The sizes of the satellites are not well known because their albedos (the surface reflectivities) are unmeasured. However, crude estimates based on the apparent brightnesses in our data and on an assumed albedo of 4% place the diameters in the range 3 to 8 km. Because the albedos are probably not less than 4%, the sizes are probably not larger than those obtained here.
The newly discovered satellites follow "irregular orbits", meaning that their orbits are large, eccentric and inclined to Jupiter's equator.
Satellites S/2000 J2 - J10 have orbital radii about 300 times the radius of Jupiter and inclinations near 150 to 160 degrees, meaning that they are retrograde. These objects join the 5 previously known retrograde satellites of Jupiter, bringing the total number of such objects to 14. New satellite S/2000 J11 falls in the prograde irregular group, with orbital radii near 150 Jupiter radii and inclinations near 30 degrees. A total of 5 such objects are now known. Lastly, S/2000 J1 occupies neither of the previously known dynamical clusters, with orbital radius near 100 Jupiter radii and inclination 45 degrees.
Irregular satellites are thought to have been captured from heliocentric orbit when Jupiter was young. The best evidence for this hypothesis is that the orbits of some of the irregular moons are actually retrograde (meaning, they orbit the planet in a direction opposite to Jupiter's rotation). Essentially the only plausible way to produce irregular satellites is by capture. However, it is not easy for Jupiter (or any other planet) to directly capture passing asteroids from heliocentric orbit. In general, some of the initial energy of the heliocentric objects must be dissipated so that Jupiter can hold on to it. The origin of the dissipation that lead to the capture of Jupiter's irregular satellites is unknown. In fact, at the present time there is no plausible source of dissipation so that capturing satellites is presently almost impossible. It is theorized, however, that the youthful Jupiter sustained a bloated atmosphere that extended far above the cloud tops of the present planet. Friction with this atmosphere could have captured the irregular satellites. In possible support of this hypothesis, we note that some of the satellites belong to dynamical groups or "families" with similar semi-major axes and inclinations. Perhaps these families were formed when initial bodies broke up on capture, due to the pressure exerted by impact with the extended atmosphere.
New Internet ResourceThe IFA Web site has a new page that carries links to Internet articles about the Institute for Astronomy and its research. The page is at http://www.ifa.hawaii.edu/info/press-releases/in_the_press.html.
Teacher OpportunitiesArt Kimura, program director for Future Flight Hawaii at UH Hilo, is looking for teachers who would like to serve on a developmental committee and/or participate as instructors. This year Future Flight is sponsoring Ellison Onizuka Space Science Day on Jan. 27. (Hope all you Big Islanders received email from us about this event.) A steering committee is being organized to plan and direct this annual event. You can get more information on the Future Flight Web site at http://www.pgd.hawaii.edu/futureflight/. If you would like to get involved with this program, please contact Art in Hilo at 934-7261.
Future Flight also offers the following opportunities:
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|Karen Meech, Institute for Astronomy, University of Hawaii firstname.lastname@example.org|