64 research outputs found
Material Around the Centaur (2060) Chiron from the 2018 November 28 UT Stellar Occultation
A stellar occultation of Gaia DR3 2646598228351156352 by the Centaur (2060)
Chiron was observed from the South African Astronomical Observatory on 2018
November 28 UT. Here we present a positive detection of material surrounding
Chiron from the 74-in telescope for this event. Additionally, a global
atmosphere is ruled out at the tens of mircobar level for several possible
atmospheric compositions. There are multiple 3-sigma drops in the 74-in light
curve: three during immersion and two during emersion. Occulting material is
located between 242-270 km from the center of the nucleus in the sky plane.
Assuming the ring-plane orientation proposed for Chiron from the 2011
occultation, the flux drops are located at 352, 344, and 316 km (immersion),
and 357, and 364 km (emersion) from the center, with normal optical depths of
0.26, 0.36, and 0.22 (immersion) and 0.26 and 0.18 (emersion), and equivalent
widths between 0.7-1.3 km. This detection is similar to the previously proposed
two-ring system and is located within the error bars of that ring-pole plane;
however, the normal optical depths are less than half of the previous values,
and three features are detected on immersion. These results suggest that the
properties of the surrounding material have evolved between the 2011, 2018, and
2022 observations.Comment: Accepted by the Planetary Science Journal 21 Oct. 2023; 13 pages, 9
figures, 4 table
Fluorescence measurements for evaluating the application of multivariate analysis techniques to optically thick environments.
Laser-induced fluorescence measurements of cuvette-contained laser dye mixtures are made for evaluation of multivariate analysis techniques to optically thick environments. Nine mixtures of Coumarin 500 and Rhodamine 610 are analyzed, as well as the pure dyes. For each sample, the cuvette is positioned on a two-axis translation stage to allow the interrogation at different spatial locations, allowing the examination of both primary (absorption of the laser light) and secondary (absorption of the fluorescence) inner filter effects. In addition to these expected inner filter effects, we find evidence that a portion of the absorbed fluorescence is re-emitted. A total of 688 spectra are acquired for the evaluation of multivariate analysis approaches to account for nonlinear effects
The structure of Chariklo's rings from stellar occultations
Two narrow and dense rings (called C1R and C2R) were discovered around the
Centaur object (10199) Chariklo during a stellar occultation observed on 2013
June 3. Following this discovery, we planned observations of several
occultations by Chariklo's system in order to better characterize the physical
properties of the ring and main body. Here, we use 12 successful occulations by
Chariklo observed between 2014 and 2016. They provide ring profiles (physical
width, opacity, edge structure) and constraints on the radii and pole position.
Our new observations are currently consistent with the circular ring solution
and pole position, to within the km formal uncertainty for the ring
radii derived by Braga-Ribas et al. The six resolved C1R profiles reveal
significant width variations from to 7.5 km. The width of the fainter
ring C2R is less constrained, and may vary between 0.1 and 1 km. The inner and
outer edges of C1R are consistent with infinitely sharp boundaries, with
typical upper limits of one kilometer for the transition zone between the ring
and empty space. No constraint on the sharpness of C2R's edges is available. A
1 upper limit of m is derived for the equivalent width of
narrow (physical width <4 km) rings up to distances of 12,000 km, counted in
the ring plane
Integration of electrostatic and fluid dynamics within a dust devil
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94610/1/jgre2050.pd
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