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It is demonstrated that the Local Sheet is both geometrically and dynamically distinct from the Local Supercluster and that the evolution of the Sheet and Local Group were probably interconnected. The Sheet is inclined by 8 degrees with…
The Lunar CRater Observations and Sensing Satellite (LCROSS) mission impacted a spent Centaur rocket stage into a permanently shadowed region near the lunar south pole. The Sheperding Spacecraft (SSC) separated \sim9 hours before impact and…
We present results of $^{12}$CO(J = 1-0) imaging observations of NGC 4567/4568, a galaxy pair in a close encounter, with Atacama Large Millimetre/submillimetre Array. For the first time, we find clear evidence of a molecular collision front…
We present estimates of the basic physical properties -- including size and albedo -- of the extreme Centaur 2013 AZ60. These properties have been derived from optical and thermal infrared measurements. Our optical measurements revealed a…
The Deep Impact encounter with the nucleus of 9P/Tempel ejected small grains (a <~ 10 micron) into the comet's coma, evidenced by thermal emission from small dust grains at mid-infrared wavelengths (~10 micron) and dynamical simulations of…
Metallic bodies that were the cores of differentiated bodies are sources of iron meteorites and are considered to have formed early in the terrestrial planet region before migrating to the main asteroid belt. Surface temperatures and mutual…
El Gordo (ACT-CL J0102-4915) is an extremely massive galaxy cluster ($M_{200} \approx 3 \times 10^{15}$ $M_{\odot}$) at redshift $z = 0.87 $ composed of two subclusters with mass ratio 3.6 merging at speed $V_{infall} \approx 2500$ km/s.…
Haumea, thought to be the Kuiper Belt's 3rd most massive object, has a fast 3.92 hr rotational period, resulting in its shape as a triaxial ellipsoid. Here, we make the first detailed predictions of Haumea's surface morphology, considering…
Via joint analysis of a calibrated telescopic survey, which found scattering Kuiper Belt objects, and models of their expected orbital distribution, we measure the form of the scattering object's size distribution. Ruling out a single…
[Condensed] We search 0.02 deg^2 for trans-Neptunian objects (TNOs) with m<=29.2 (diameter ~15 km) using the ACS on HST. Three new objects are discovered, roughly 25 times fewer than expected from extrapolation of the differential sky…
Impact crater counts on the Saturnian satellites are a key element for estimating their surface ages and placing constraints on their impactor population. The Cassini mission radar observations allowed crater counts to be made on the…
We present time-resolved photometric observations of Jupiter family comet 17P/Holmes during its dramatic outburst of 2007. The observations, from the orbiting Solar Mass Ejection Imager (SMEI), provide the most complete measure of the…
The discovery of a large putative impact crater buried beneath Hiawatha Glacier along the margin of the northwestern Greenland Ice Sheet has reinvigorated interest into the nature of large impacts into thick ice masses. This circular…
On June 30, 1908, at about 0h 14.5m UTC, the Tunguska Event (TE) occurred, most likely caused by the fall of a small stony asteroid of about 50-80 meters in diameter over the basin of the Tunguska River (Central Siberia). This paper will…
Late accretion is a process that strongly modulated surface geomorphic and geochemical features of Mercury. Yet, the fate of the impactors and their effects on Mercury's surface through the bombardment epoch are not clear. Using Monte-Carlo…
Among asteroid families, the Astrid family is peculiar because of its unusual inclination distribution. Objects at $a\simeq$~2.764 au are quite dispersed in this orbital element, giving the family a "crab-like" appearance. Recent works…
HST ACS images of the young SN remnant Cas A are used to explore the expansion and spatial distribution of its highest velocity debris. Proper motions of over 1800 outlying ejecta knots are reported. The distribution of transverse expansion…
The trailing hemisphere of Dione is characterized by the Wispy Terrain, where it exhibits a hemispheric-scale network of extensional tectonic faults superposed on the moon's cratered surface. The faults likely reflect past endogenic…
Between 2019 and 2024, we used the Gemini-N and JWST observatories to conduct a detailed case study of the active Centaur 450P/LONEOS, whose orbit was significantly altered by a close Saturn encounter in 1992. Gemini-N GMOS optical images…
We present the global distribution of fine structure infrared line emission in the Cassiopeia A supernova remnant using data from the Spitzer Space Telescope's Infrared Spectrograph. We identify emission from ejecta materials in the…