Abstract The DECam Ecliptic Exploration Project (DEEP) is a deep survey of the trans-Neptunian solar system being carried out on the 4 m Blanco telescope at the Cerro Tololo Inter-American ...Observatory in Chile using the Dark Energy Camera (DECam). By using a shift-and-stack technique to achieve a mean limiting magnitude of r ∼ 26.2, DEEP achieves an unprecedented combination of survey area and depth, enabling quantitative leaps forward in our understanding of the Kuiper Belt populations. This work reports results from an analysis of 20, 3 deg 2 DECam fields along the invariable plane. We characterize the efficiency and false-positive rates for our moving-object detection pipeline, and use this information to construct a Bayesian signal probability for each detected source. This procedure allows us to treat all of our Kuiper Belt object (KBO) detections statistically, simultaneously accounting for efficiency and false positives. We detect approximately 2300 candidate sources with KBO-like motion with signal-to-noise ratios > 6.5. We use a subset of these objects to compute the luminosity function of the Kuiper Belt as a whole, as well as the cold classical (CC) population. We also investigate the absolute magnitude ( H ) distribution of the CCs, and find consistency with both an exponentially tapered power law, which is predicted by streaming instability models of planetesimal formation, and a rolling power law. Finally, we provide an updated mass estimate for the CC Kuiper Belt of M CC ( H r < 12 ) = 0.0017 − 0.0004 + 0.0010 M ⊕ , assuming albedo p = 0.15 and density ρ = 1 g cm −3 .
•We investigated the distribution of constituents on the classical Uranian satellites.•Red material is most abundant on the leading hemispheres of the outer moons.•Distribution of red material is ...consistent with mantling by irregular satellite dust.•We detected a spot of enhanced reddening on Titania's leading hemisphere.•We detected a weak 2.2 µm absorption feature in some spectra, possibly NH3-hydrates.
The large and tidally-locked “classical” moons of Uranus display longitudinal and planetocentric trends in their surface compositions. Spectrally red material has been detected primarily on the leading hemispheres of the outer moons, Titania and Oberon. Furthermore, detected H2O ice bands are stronger on the leading hemispheres of the classical satellites, and the leading/trailing asymmetry in H2O ice band strengths decreases with distance from Uranus. We hypothesize that the observed distribution of red material and trends in H2O ice band strengths results from infalling dust from Uranus’ irregular satellites. These dust particles migrate inward on slowly decaying orbits, eventually reaching the classical satellite zone, where they collide primarily with the outer moons. The latitudinal distribution of dust swept up by these moons should be fairly even across their southern and northern hemispheres. However, red material has only been detected over the southern hemispheres of these moons, during the Voyager 2 flyby of the Uranian system (subsolar latitude ∼81°S). Consequently, to test whether irregular satellite dust impacts drive the observed enhancement in reddening, we have gathered new ground-based data of the now observable northern hemispheres of these satellites (sub-observer latitudes ∼17–35°N). Our results and analyses indicate that longitudinal and planetocentric trends in reddening and H2O ice band strengths are broadly consistent across both southern and northern latitudes of these moons, thereby supporting our hypothesis. Utilizing a suite of numerical best fit models, we investigate the composition of the reddening agent, finding that both complex organics and amorphous pyroxene match the spectral slopes of our data. We also present spectra that span L/L’ bands (∼2.9–4.1 µm), a previously unexplored wavelength range in terms of spectroscopy for the Uranian satellites, and we compare the shape and albedo of the spectral continua in these L/L’ band data to other icy moons in the Jovian and Saturnian systems. Additionally, we discuss possible localized enhancement of reddening on Titania, subtle differences in H2O ice band strengths between the southern and northern hemispheres of the classical satellites, the distribution of constituents on Miranda, and the possible presence of NH3-hydrates on these moons. In closing, we explore potential directions for future observational and numerical modeling work in the Uranian system.
► We examine space weathering within the large, old Koronis asteroid family. ►We identified a trend of increasing spectral slope with increasing size. ►This trend displays the transition from Q- to ...S-type bodies in the Koronis family. ►This suggests that a number of fresh, Q-type bodies are present in the family.
The space weathering process and its implications for the relationships between S- and Q-type asteroids and ordinary chondrite meteorites is an often debated topic in asteroid science. Q-type asteroids have been shown to display the best spectral match to ordinary chondrites (McFadden, L.A., Gaffey, M.J., McCord, T.B. 1985. Science 229, 160–163). While the Q-types and ordinary chondrites share some spectral features with S-type asteroids, the S-types have significantly redder spectral slopes than the Q-types in visible and near-infrared wavelengths. This reddening of spectral slope is attributed to the effects of space weathering on the observed surface composition. The analysis by Binzel et al. (Binzel, R.P., Rivkin, A.S., Stuart, J.S., Harris, A.W., Bus, S.J., Burbine, T.H. 2004. Icarus 170, 259–294) provided a missing link between the Q- and S-type bodies in near-Earth space by showing a reddening of spectral slope in objects from 0.1 to 5km that corresponded to a transition from Q-type to S-type asteroid spectra, implying that size, and therefore surface age, is related to the relationship between S- and Q-types. The existence of Q-type asteroids in the main-belt was not confirmed until Mothé-Diniz and Nesvorny (Mothé-Diniz, T., Nesvorny, D. 2008. Astron. Astrophys. 486, L9–L12) found them in young S-type clusters. The young age of these families suggest that the unweathered surface could date to the formation of the family. This leads to the question of whether older S-type main-belt families can contain Q-type objects and display evidence of a transition from Q- to S-type. To answer this question we have carried out a photometric survey of the Koronis family using the Kitt Peak 2.1m telescope. This provides a unique opportunity to compare the effects of the space weathering process on potentially ordinary chondrite-like bodies within a population of identical initial conditions. We find a trend in spectral slope for objects 1–5km that shows the transition from Q- to S-type in the main-belt. This data set will prove crucial to our understanding of the space weathering process and its relevant timescales.
•We present photometric color observations for the 42 largest L5 Jupiter Trojans.•We calculate a color principal component for separating DLike and XLike objects.•Our sample contains 76% redder DType ...objects and 24% less red X and Ctype objects.•Our sample shows no noticeable difference in color distribution with inclination.
The L5 Jupiter Trojan asteroids are minor bodies that orbit 60 degrees behind Jupiter. Because these orbits are stable over the lifetime of the Solar System, the properties of these objects may inform us about the conditions under which the Solar System formed. We present BVRKCIKC photometry for the 42 intrinsically brightest and presumably largest members of the L5 Jupiter Trojans. We define a new principal color component aT* that is indicative of taxonomic types relevant to the Jupiter Trojan asteroids. We find that 76% of the largest L5 Jupiter Trojans are consistent with a D-type classification, while 24% show shallower slopes more consistent with X-type and C-Type classifications. Such a breakdown is consistent with other surveys and will help to place the Trojans in the larger context of the Solar System.
We present the faintest mid-ecliptic latitude survey in the second part of Hubble Space Telescope archival search for outer solar system bodies. We report the discovery of 28 new trans-Neptunian ...objects and one small centaur (R ~ 2 km) in the band 5?-20? off the ecliptic. The inclination distribution of these excited objects is consistent with the distribution derived from brighter ecliptic surveys. We suggest that the size and inclination distribution should be estimated consistently using suitable surveys with calibrated search algorithms and reliable orbital information.
We report high-precision photometry of three small and one larger Kuiper Belt objects (KBOs) obtained with the Advanced Camera for Surveys on board the Hubble Space Telescope. The three small bodies ...are the smallest KBOs for which light-curve measurements are available. The object 2003 BF91 has a diameter of 20 km (assuming 10% albedo) and a 1.09 mag, 9.1 hr light curve that is feasibly explained by the rotation of an elongated, coherent body supported by material strength and best imagined as an icy outer solar system analog to asteroid (243) Ida. Two other small KBOs, 2003 BG91 and 2003 BH91 (diameters 31 and 18 km, with albedo 10%), exhibit an unremarkable light curve and no detectable photometric variation, respectively. For the larger KBO 2000 FV53 (116 km diameter, assuming 10% albedo) we strongly detect a nonsinusoidal periodic (7.5 hr) brightness variation with a very small amplitude (0.07 mag). This KBO may be nearly spherical, a result that might not be unusual in the Kuiper Belt but would be remarkable among outer solar system satellites of similar size. Light curves may be caused by variations in albedo or shape, and we carry out a study of possible physical states and bulk densities under the assumptions of both fluid equilibrium and finite, nonzero internal friction. Under most assumptions, the densities for these KBOs are likely in the range 1-2 g cm-3, and a plausible solution for 2000 FV53 is a rubble pile of this density that is held slightly out of the minimum-energy shape by internal friction among constituent blocks that are relatively small. Our interpretation of 2000 FV53 as a pulverized but essentially primordial object and 2003 BF91 as a collisional fragment is consistent with models of collisional timescales in the outer solar system. We compile all published KBO light-curve data to date and compare our results to the larger population.
A survey of small (<5–10
km diameter) members of the Koronis family shows some objects with visible-wavelength broadband colors consistent with membership in the Q-class (Tholen, D.J. 1984. Asteroid ...taxonomy from cluster analysis of photometry. Ph.D. Dissertation, University of Arizona, Tucson, AZ; Bus, S.J., Binzel, R.P. 2002. Icarus 158, 146–177). This agrees with an ordinary chondritic composition for this family and suggests the timescale for changing Q-class to S-class spectra in the main belt is roughly comparable to the regolith refresh time in the 2–5
km size range.
The Structure of the β Leonis Debris Disk Stock, Nathan D; Su, Kate Y. L; Liu, Wilson ...
The Astrophysical journal,
12/2010, Letnik:
724, Številka:
2
Journal Article
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