Saturn's Rings Thermal Opposition Effect with Decreasing Solar Elevation as seen by Cassini CIRS

Details Saturn's Rings Thermal Opposition Effect with Decreasing Solar Elevation as seen by Cassini CIRS Saturn's Rings Thermal Opposition Effect with Decreasing Solar Elevation as seen by Cassini CIRS

Oct 2010

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010dps....42.2206d&link_type=abstract

American Astronomical Society, DPS meeting #42, #22.06; Bulletin of the American Astronomical Society, Vol. 42, p.989

Astronomy and Astrophysics

Astronomy

Scientific paper

From 2004 to 2010, the Composite Infrared Spectrometer (CIRS) onboard Cassini spacecraft took more than 50,000 spectra of the rings. By fitting the Focal Plane 1 (FP1) spectra (16.67 - 1000 microns) with a blackbody model (Spilker et al. 2005, Planetary and Space Science 2006, vol. 54 pp1167-1176), we obtain the effective ring temperature T and the scale factor β, which includes the filling factor.
We derived thermal phase curves, i.e. temperature as a function of phase angle, for 15 ring regions of 3000km across and for different ranges of solar elevation (0°< |B'|< 25°).The thermal phase curves from almost zero to 50 degrees phase angle do not show any small surge (< 3°) contrary to that previously observed at optical wavelengths, mainly due to lack of high data sampling at low phase angles. They are well fit by a linear function, for which we defined a slope and a temperature corresponding to the near-zero phase angle. At equinox, when the solar elevation is zero, thermal phase curves are flat and temperatures are the coldest ever reached during the prime and equinox missions.
The trends of the temperature's decrease with phase angle for decreasing solar elevation are different for the thickest ring (B ring) and the thinnest ring (C ring). In the B ring, the absolute slope of thermal phase curves increases with decreasing solar elevation |B'| whereas the thermal phase curves of the C ring at different |B'| seem almost parallel. We attribute these variations to the shadowing effect that is a combination of the fraction of non-hidden particles as seen by the observer and by the Sun.
Interestingly, the filling factor β from CIRS spectra decreases with decreasing solar elevation. This implies that the shadowing effect could play a role in both parameters β and T.

Affiliated with

Also associated with

No associations

Rating

Saturn's Rings Thermal Opposition Effect with Decreasing Solar Elevation as seen by Cassini CIRS 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 Saturn's Rings Thermal Opposition Effect with Decreasing Solar Elevation as seen by Cassini CIRS, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Saturn's Rings Thermal Opposition Effect with Decreasing Solar Elevation as seen by Cassini CIRS will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1122221