1,215 research outputs found
Detection of arcs in Saturn's F ring during the 1995 Sun ring-plane crossing
Observations of the November 1995 Sun crossing of the Saturn's ring-plane
made with the 3.6m CFH telescope, using the UHAO adaptive optics system, are
presented here. We report the detection of four arcs located in the vicinity of
the F ring. They can be seen one day later in HST images. The combination of
both data sets gives accurate determinations of their orbits. Semi-major axes
range from 140020 km to 140080 km, with a mean of 140060 +- 60 km. This is
about 150 km smaller than previous estimates of the F ring radius from Voyager
1 and 2 data, but close to the orbit of another arc observed at the same epoch
in HST images.Comment: 8 pages, 3 figures, 1 table, To appear in A&A, for comments :
[email protected]
Church Directory and List of Preachers of Churches of Christ
https://digitalcommons.acu.edu/crs_books/1576/thumbnail.jp
Church Directory and List of Preachers of Churches of Christ
https://digitalcommons.acu.edu/crs_books/1403/thumbnail.jp
Is the Church of Christ A Denomination?
https://digitalcommons.acu.edu/crs_books/1076/thumbnail.jp
Christ in History, An Appreciation: An Address delivered before the graduating class of Harding College, Searcy, Arkansas, June, 1944.
https://digitalcommons.acu.edu/crs_books/1172/thumbnail.jp
Galileo In-Situ Dust Measurements in Jupiter's Gossamer Rings
During its late orbital mission at Jupiter the Galileo spacecraft made two
passages through the giant planet's gossamer ring system. The impact-ionization
dust detector on board successfully recorded dust impacts during both ring
passages and provided the first in-situ measurements from a dusty planetary
ring. In all, a few thousand dust impacts were counted with the instrument
accumulators during both ring passages, but only a total of 110 complete data
sets of dust impacts were transmitted to Earth. Detected particle sizes range
from about 0.2 to 5 micron, extending the known size distribution by an order
of magnitude towards smaller particles than previously derived from optical
imaging (Showalter et al. 2008). The grain size distribution increases towards
smaller particles and shows an excess of these tiny motes in the Amalthea
gossamer ring compared to the Thebe ring. The size distribution for the
Amalthea ring derived from our in-situ measurements for the small grains agrees
very well with the one obtained from images for large grains. Our analysis
shows that particles contributing most to the optical cross-section are about 5
micron in radius, in agreement with imaging results. The measurements indicate
a large drop in particle flux immediately interior to Thebe's orbit and some
detected particles seem to be on highly-tilted orbits with inclinations up to
20 deg.Comment: 13 figures, 4 tables, submitted to Icaru
Quantum graphs with singular two-particle interactions
We construct quantum models of two particles on a compact metric graph with
singular two-particle interactions. The Hamiltonians are self-adjoint
realisations of Laplacians acting on functions defined on pairs of edges in
such a way that the interaction is provided by boundary conditions. In order to
find such Hamiltonians closed and semi-bounded quadratic forms are constructed,
from which the associated self-adjoint operators are extracted. We provide a
general characterisation of such operators and, furthermore, produce certain
classes of examples. We then consider identical particles and project to the
bosonic and fermionic subspaces. Finally, we show that the operators possess
purely discrete spectra and that the eigenvalues are distributed following an
appropriate Weyl asymptotic law
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