- ID:
- ivo://CDS.VizieR/J/A+A/610/A21
- Title:
- KiDS Survey for solar system objects mining
- Short Name:
- J/A+A/610/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The search for minor bodies in the Solar System promises insights into its formation history. Wide imaging surveys offer the opportunity to serendipitously discover and identify these traces of planetary formation and evolution. We present a method to acquire position, photometry, and proper motion measurements of Solar System objects in surveys using dithered image sequences. The application of this method on the Kilo-Degree Survey is demonstrated. Optical images of 346deg^2^ fields of the sky are searched in up to four filters using the AstrOmatic software suite to reduce the pixel to catalog data. The Solar System objects within the acquired sources are selected based on a set of criteria depending on their number of observation, motion, and size. The Virtual Observatory SkyBoT tool is used to identify known objects. We observed 20,221 SSO candidates, with an estimated false-positive content of less than 0.05%. Of these SSO candidates, 53.4% are identified by SkyBoT. KiDS can detect previously unknown SSOs because of its depth and coverage at high ecliptic latitude, including parts of the Southern Hemisphere. Thus we expect the large fraction of the 46.6% of unidentified objects to be truly new SSOs. Our method is applicable to a variety of dithered surveys such as DES, LSST, and Euclid. It offers a quick and easy-to-implement search for Solar System objects. SkyBoT can then be used to estimate the completeness of the recovered sample.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/653/A57
- Title:
- (216) Kleopatra images
- Short Name:
- J/A+A/653/A57
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The recent estimates of the 3D shape of the M/Xe-type triple asteroid system (216) Kleopatra indicated a density of ~5g/cm^3^, which is by far the highest for a small Solar System body. Such a high density implies a high metal content as well as a low porosity which is not easy to reconcile with its peculiar "dumbbell" shape. Given the unprecedented angular resolution of the VLT/SPHERE/ZIMPOL camera, here, we aim to constrain the mass (via the characterization of the orbits of the moons) and the shape of (216) Kleopatra with high accuracy, hence its density. We combined our new VLT/SPHERE observations of (216) Kleopatra recorded during two apparitions in 2017 and 2018 with archival data from the W.M. Keck Observatory, as well as lightcurve, occultation, and delay-Doppler images, to derive a model of its 3D shape using two different algorithms (ADAM, MPCD). Furthermore, an N-body dynamical model allowed us to retrieve the orbital elements of the two moons as explained in the accompanying paper. The shape of (216) Kleopatra is very close to an equilibrium dumbbell figure with two lobes and a thick neck. Its volume equivalent diameter (118.75+/-1.40)km and mass (2.97+/-0.32)*10^18^kg (i.e., 56% lower than previously reported) imply a bulk density of (3.38+/-0.50)g/cm^3^. Such a low density for a supposedly metal-rich body indicates a substantial porosity within the primary. This porous structure along with its near equilibrium shape is compatible with a formation scenario including a giant impact followed by reaccumulation. (216) Kleopatra's current rotation period and dumbbell shape imply that it is in a critically rotating state. The low effective gravity along the equator of the body, together with the equatorial orbits of the moons and possibly rubble-pile structure, opens the possibility that the moons formed via mass shedding.
- ID:
- ivo://CDS.VizieR/J/ApJS/237/19
- Title:
- KMTNet LCs of ~1000 main-belt asteroids
- Short Name:
- J/ApJS/237/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VRI spectrophotometry of 1003 main-belt asteroids (MBAs) observed with the Sutherland, South Africa node of the Korea Microlensing Telescope Network (KMTNet). All of the observed MBAs were serendipitously captured in KMTNet's large 2{deg}x2{deg} field of view during a separate targeted near-Earth Asteroid study. Our broadband spectrophotometry is reliable enough to distinguish among four asteroid taxonomies and we confidently categorize 836 of the 1003 observed targets as either a S-, C-, X-, or D-type asteroid by means of a machine learning algorithm approach. Our data show that the ratio between S-type MBAs and (C+X+D)-type MBAs, with H magnitudes between 12 and 18 (12km>~diameter>~0.75km), is almost exactly 1:1. Additionally, we report 0.5-3hr (median: 1.3hr) light-curve data for each MBA and we resolve the complete rotation periods and amplitudes for 59 targets. Of the 59 targets, 2 have rotation periods potentially below the theoretical zero-cohesion boundary limit of 2.2hr. We report lower limits for the rotation periods and amplitudes for the remaining targets. Using the resolved and unresolved light curves we determine the shape distribution for this population using a Monte Carlo simulation. Our model suggests a population with an average elongation b/a=0.74+/-0.07 and also shows that this is independent of asteroid size and taxonomy.
- ID:
- ivo://CDS.VizieR/J/AJ/154/162
- Title:
- KMTNet-SAAO observation of near-Earth asteroids
- Short Name:
- J/AJ/154/162
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here VRI spectrophotometry of 39 near-Earth asteroids (NEAs) observed with the Sutherland, South Africa, node of the Korea Microlensing Telescope Network (KMTNet). Of the 39 NEAs, 19 were targeted, but because of KMTNet's large 2{deg}x2{deg} field of view, 20 serendipitous NEAs were also captured in the observing fields. Targeted observations were performed within 44 days (median: 16 days, min: 4 days) of each NEA's discovery date. Our broadband spectrophotometry is reliable enough to distinguish among four asteroid taxonomies and we were able to confidently categorize 31 of the 39 observed targets as either an S-, C-, X-, or D-type asteroid by means of a Machine Learning algorithm approach. Our data suggest that the ratio between "stony" S-type NEAs and "not-stony" (C+X+D)-type NEAs, with H magnitudes between 15 and 25, is roughly 1:1. Additionally, we report ~1 hr light curve data for each NEA, and of the 39 targets, we were able to resolve the complete rotation period and amplitude for six targets and report lower limits for the remaining targets.
- ID:
- ivo://CDS.VizieR/J/AJ/142/120
- Title:
- 104 large asteroids mass determination studies
- Short Name:
- J/AJ/142/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The techniques described in an earlier paper were used to determine masses of 104 asteroids by the method of asteroid-asteroid gravitational interaction. For each of the 104 perturbers, 4 large sets of test particles selected by different criteria were used to calculate 4 mass values from a weighted mean of individual results within each set.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A56
- Title:
- Largest main belt asteroids data
- Short Name:
- J/A+A/654/A56
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Until recently, the 3D shape, and therefore density (when combining the volume estimate with available mass estimates), and surface topography of the vast majority of the largest (D>=100km) main-belt asteroids have remained poorly constrained. The improved capabilities of the SPHERE/ZIMPOL instrument have opened new doors into ground-based asteroid exploration. To constrain the formation and evolution of a representative sample of large asteroids, we conducted a high-angular-resolution imaging survey of 42 large main-belt asteroids with VLT/SPHERE/ZIMPOL. Our asteroid sample comprises 39 bodies with D>=100km and in particular most D>=200km main-belt asteroids (20/23). Furthermore, it nicely reflects the compositional diversity present in the main belt as the sampled bodies belong to the following taxonomic classes: A, B, C, Ch/Cgh, E/M/X, K, P/T, S, and V. The SPHERE/ZIMPOL images were first used to reconstruct the 3D shape of all targets with both the ADAM and MPCD reconstruction methods. We subsequently performed a detailed shape analysis and constrained the density of each target using available mass estimates including our own mass estimates in the case of multiple systems. The analysis of the reconstructed shapes allowed us to identify two families of objects as a function of their diameters, namely "spherical" and "elongated" bodies. A difference in rotation period appears to be the main origin of this bimodality. In addition, all but one object (216 Kleopatra) are located along the Maclaurin sequence with large volatile-rich bodies being the closest to the latter. Our results further reveal that the primaries of most multiple systems possess a rotation period of shorter than 6h and an elongated shape (c/a<=0.65). Densities in our sample range from ~1.3g/cm^3^ (87 Sylvia) to ~4.3g/cm^3^ (22 Kalliope). Furthermore, the density distribution appears to be strongly bimodal with volatile poor ({rho}>=2.7g/cm^3^) and volatile-rich ({rho}>=2.2g/cm^3^) bodies. Finally, our survey along with previous observations provides evidence in support of the possibility that some C-complex bodies could be intrinsically related to IDP-like P- and D-type asteroids, representing different layers of a same body (C: core; P/D: outer shell). We therefore propose that P/ D-types and some C-types may have the same origin in the primordial trans-Neptunian disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/L21
- Title:
- LC of the TNO Varuna
- Short Name:
- J/ApJ/883/L21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From CCD observations carried out with different telescopes, we present short-term photometric measurements of the large trans-Neptunian object Varuna in 10 epochs, spanning around 19 years. We observe that the amplitude of the rotational light curve has changed considerably during this period of time from 0.41 to 0.55mag. In order to explain this variation, we constructed a model in which Varuna has a simple triaxial shape, assuming that the main effect comes from the change of the aspect angle as seen from Earth, due to Varuna's orbital motion in the 19yr time span. The best fits to the data correspond to a family of solutions with axial ratios b/a between 0.56 and 0.60. This constrains the pole orientation in two different ranges of solutions presented here as maps. Apart from the remarkable variation of the amplitude, we have detected changes in the overall shape of the rotational light curve over shorter timescales. After the analysis of the periodogram of the residuals to a 6.343572hr double-peaked rotational light-curve fit, we find a clear additional periodicity. We propose that these changes in the rotational light-curve shape are due to a large and close-in satellite whose rotation induces the additional periodicity. The peak-to-valley amplitude of this oscillation is in the order of 0.04mag. We estimate that the satellite orbits Varuna with a period of 11.9819hr (or 23.9638hr), assuming that the satellite is tidally locked, at a distance of ~1300km (or ~2000km) from Varuna, outside the Roche limit.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A98
- Title:
- Lightcurve inversion for 491 asteroids
- Short Name:
- J/A+A/649/A98
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We perform lightcurve inversion for 491 asteroids to retrieve phase curve parameters, rotation periods, pole longitudes and latitudes, and convex and triaxial ellipsoid shapes by using the sparse photometric observations from Gaia Data Release 2 and the dense ground-based observations from the DAMIT data base. We develop a method for the derivation of reference absolute magnitudes and phase curves from the Gaia data, allowing for comparative studies among hundreds of asteroids.
- ID:
- ivo://CDS.VizieR/J/A+A/576/A18
- Title:
- Light curve of (2060) Chiron
- Short Name:
- J/A+A/576/A18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose that several short-duration events observed in past stellar occultations by Chiron were produced by ring material. Some similarities between these events and the characteristics of Chariklo's rings could indicate common mechanisms around centaurs. From a reanalysis of the stellar occultation data in the literature, we determined two possible orientations of the pole of Chiron's rings, with ecliptic coordinates {lambda}=(352+/-10){deg}, {beta}=(37+/-10){deg} or {lambda}=(144+/-10){deg}, {beta}=(24+/-10){deg}. The mean radius of the rings is (324+/-10)km. One can use the rotational lightcurve amplitude of Chiron at different epochs to distinguish between the two solutions for the pole. Both solutions imply a lower lightcurve amplitude in 2013 than in 1988, when the rotational lightcurve was first determined. We derived Chiron's rotational lightcurve in 2013 from observations at the 1.23m CAHA telescope, and indeed its amplitude was smaller than in 1988. We also present a rotational lightcurve in 2000 from images taken at the CASLEO 2.15m telescope that is consistent with our predictions. Out of the two poles, the {lambda}=(144+/-10){deg}, {beta}=(24+/-10){deg} solution provides a better match to a compilation of rotational lightcurve amplitudes from the literature and those presented here. We also show that using this preferred pole orientation, Chiron's long-term brightness variations are compatible with a simple model that incorporates the changing brightness of the rings while the tilt angle with respect to the Earth is changing with time. Also, the variability of the water ice band in Chiron's spectra as seen in the literature can be explained to a large degree by an icy ring system whose tilt angle changes with time and whose composition includes water ice, analogously to the case of Chariklo. We present several possible formation scenarios for the rings from qualitative points of view and speculate on why rings might be common in centaurs. We also speculate on whether the known bimodal color distribution of the centaurs could be due to centaurs with rings and centaurs without rings.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A48
- Title:
- Light curves of asteroid (25143) Itokawa
- Short Name:
- J/A+A/562/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-Earth asteroid (25143) Itokawa was visited by the Hayabusa spacecraft in 2005, resulting in a highly detailed shape and surface topography model. This model has led to several predictions for the expected radiative torques on this asteroid, suggesting that its spin rate should be decelerating. To detect changes in rotation rate that may be due to YORP-induced radiative torques, which in turn may be used to investigate the interior structure of the asteroid. Through an observational survey spanning 2001 to 2013 we obtained rotational lightcurve data at various times over the last five close Earth-approaches of the asteroid. We applied a polyhedron-shape-modelling technique to assess the spin-state of the asteroid and its long term evolution. We also applied a detailed thermophysical analysis to the shape model determined from the Hayabusa spacecraft. We have successfully measured an acceleration in Itokawa's spin rate of dw/dt=(3.54+/-0.38)*10^-8^rad/day^2^, equivalent to a decrease of its rotation period of ~45ms/yr. From the thermophysical analysis we find that the center-of-mass for Itokawa must be shifted by ~21m along the long-axis of the asteroid to reconcile the observed YORP strength with theory. This can be explained if Itokawa is composed of two separate bodies with very different bulk densities of 1750+/-110kg/m^3^ and 2850+/-500kg/m^3^, and was formed from the merger of two separate bodies, either in the aftermath of a catastrophic disruption of a larger differentiated body, or from the collapse of a binary system. We therefore demonstrate that an observational measurement of radiative torques, when combined with a detailed shape model, can provide insight into the interior structure of an asteroid. Futhermore, this is the first measurement of density inhomogeneity within an asteroidal body, that reveals significant internal structure variation. A specialised spacecraft is normally required for this.
