New Long-Wavelength Radio Source Occultations by Saturn's Rings

Details New Long-Wavelength Radio Source Occultations by Saturn's Rings New Long-Wavelength Radio Source Occultations by Saturn's Rings

Oct 2000

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000dps....32.4803b&link_type=abstract

American Astronomical Society, DPS Meeting #32, #48.03; Bulletin of the American Astronomical Society, Vol. 32, p.1086

Astronomy and Astrophysics

Astronomy

Scientific paper

Three point-like extragalactic radio sources have been observed passing behind the rings of Saturn, and the varying attenuation of the background sources' intensities result in radial profiles of ring opacity. These events took place in September 1998, February 1999, and October 1999, with the opening angle of the rings varying from -16o to -20o. The first and last events were observed with the Very Large Array and the middle one with the Australian Telescope Compact Array. Collectively the occultation geometries probe all ring radii. All three events were observed at 20 cm wavelength with one event also observed at 90 cm wavelength, and hence they probe the distribution of ring particles with sizes larger than ~ 10 cm. The source fluxes at λ 20 cm are 6 mJy, 30 mJy, and 25 mJy respectively, compared to the (extended) Saturn thermal emission of order 100 mJy. The relative weakness of the first source was compensated for by the slower apparent motion of Saturn at opposition which occurred near that event. Thermal emission from the rings was not detectable due to their extremely low emissivity at these wavelengths. The events were predicted by a search of point sources in the NRAO VLA Sky Survey catalog [Condon et al. (1998), AJ 115, 1693], and subsequent high resolution mapping confirmed their positions and compactness. For an unresolved source, our radial resolution in the rings is ultimately limited by the Fresnel zone diameter of √ {2λ D} = 720√ {λ /21 cm} km. This work extends the radio occultation experiment carried out by the Voyager I spacecraft [Marouf et al. (1983), Icarus 54, 189], which determined opacity profiles of the rings at λ 4 cm and λ 13 cm. Observations of occultations of natural radio sources by Saturn at longer wavelengths provide a similar direct probe of the ring particle sizes in the dynamically-important 30 cm--10 m size range.

Affiliated with

Also associated with

No associations

Rating

New Long-Wavelength Radio Source Occultations by Saturn's Rings does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with New Long-Wavelength Radio Source Occultations by Saturn's Rings, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and New Long-Wavelength Radio Source Occultations by Saturn's Rings will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-867308