نتایج جستجو برای: asteroid hyalosis
تعداد نتایج: 3443 فیلتر نتایج به سال:
OBJECTIVE To evaluate the ability of stereoscopic nonmydriatic digital retinal imaging to detect ocular pathologic features other than diabetic retinopathy (DR) in patients with diabetes mellitus (DM) compared with dilated retinal examination by retinal specialist ophthalmologists. DESIGN Clinic-based comparative instrument study and retrospective chart review. PARTICIPANTS Two hundred eigh...
We show that Directed Energy (DE) systems offer the potential for true planetary defense from small to km class threats. Directed energy has evolved dramatically recently and is on an extremely rapid ascent technologically. It is now feasible to consider DE systems for threats from asteroids and comets. DE-STAR (Directed Energy System for Targeting of Asteroids and exploRation) is a phased-arra...
The asteroid 2003 EH1, proposed as the parent body of the Quadrantid meteor shower, is thought to be the remnant of a past cometary object, tentatively identified with the historical comets C/1490 Y1 and C/1385 U1. In the present work we use recovery astrometry to extend the observed arc of 2003 EH1 from 10 months to about 5 years, enough to exclude the proposed direct relationship of the aster...
Introduction: As Dawn’s ion engine propels the spacecraft toward the asteroid belt, there is growing interest in the asteroids as planetary predecessors. Pallas is the third largest asteroid, similar in size to Vesta, and has an orbit similar to that of Ceres. Pallas is one of the three objects in the main belt that may be a proto-planet rather than a fragment or remnant of the early solar system.
It is well known that asteroid families have steeper absolute magnitude (H) distributions for H 12–13 values than the background population. Beyond this threshold, the shapes of the absolute magnitude distributions in the family/background populations are difficult to determine, primarily because both populations are not yet observationally complete. Using a recently generated catalog containin...
The asteroid observations made with the automatic meridian circle at Bordeaux observatory from 1985 to 1994, and which have recently become available, are presented. The residuals of these observations obtained using the orbital elements published in the “Ephemerides of Minor Planets for 1996” are analysed. An anomaly for the asteroid (17) Thetis was found, indicating a current close encounter ...
The zodiacal dust bands are bright infrared (IR) strips produced by thermal emission from circumsolar rings of particles. Two of the three principal dust bands, known as b and g, were previously linked to the recent asteroid collisions that produced groups of fragments, so-called asteroid families, near the orbits of (832) Karin and (490) Veritas. The origin of the third, near-ecliptic a band h...
We present a procedure for asteroids 3D surface reconstruction from images for close approach distances. Different from other 3D reconstruction scenario from spacecraft images, the closer flyby gave the chance to revolve around the asteroid shape and thus acquiring images from different viewpoints with a higher baseline. The chance to have more information of the asteroids surface is however pa...
RESUME We use a 2-D hybrid code (fluid electrons, particle ions) to simulate the interaction of the solar wind with a magnetized asteroid. The asteroid field is taken as a dipole with different strengths. For a small magnetic moment a whistler wake is generated. Stronger dipoles generate a magnetosonic perturbation. We compare simulation results with the signatures observed by Galileo near Gasp...
Asteroids with satellites are natural laboratories to constrain the formation and evolution of our solar system. The binary Trojan asteroid (624) Hektor is the only known Trojan asteroid to possess a small satellite. Based on W. M. Keck adaptive optics observations, we found a unique and stable orbital solution, which is uncommon in comparison to the orbits of other large multiple asteroid syst...
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