- ID:
- ivo://CDS.VizieR/J/AJ/154/62
- Title:
- Orbital parameters of Kuiper Belt objects
- Short Name:
- J/AJ/154/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measured the mean plane of the Kuiper Belt as a function of semimajor axis. For the classical Kuiper Belt as a whole (the nonresonant objects in the semimajor axis range 42-48au), we find a mean plane of inclination i_m_=1.8{deg}_-0.4{deg}_^+0.7{deg}^ and longitude of ascending node {Omega}_m_=77{deg}_-14{deg}_^+18{deg}^ (in the J2000 ecliptic-equinox coordinate system), in accord with theoretical expectations of the secular effects of the known planets. With finer semimajor axis bins, we detect a statistically significant warp in the mean plane near semimajor axes 40-42au. Linear secular theory predicts a warp near this location due to the {nu}_18_ nodal secular resonance; however, the measured mean plane for the 40.3-42au semimajor axis bin (just outside the {nu}_18_) is inclined ~13{deg} to the predicted plane, a nearly 3{sigma} discrepancy. For the more distant Kuiper Belt objects of semimajor axes in the range 50-80au, the expected mean plane is close to the invariable plane of the solar system, but the measured mean plane deviates greatly from this: it has inclination i_m_=9.1{deg}_-3.8{deg}_^+6.6{deg}^ and longitude of ascending node {Omega}_m_=227{deg}_-44{deg}_^+18{deg}^. We estimate this deviation from the expected mean plane to be statistically significant at the ~97%-99% confidence level. We discuss several possible explanations for this deviation, including the possibility that a relatively close-in (a<~100au), unseen, small planetary-mass object in the outer solar system is responsible for the warping.
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- ID:
- ivo://CDS.VizieR/J/AJ/116/1998
- Title:
- Outer planetary systems
- Short Name:
- J/AJ/116/1998
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to better understand the range of dynamically long-lived giant planet systems, we present the results of a set of bottom-up numerical simulations designed to generate plausible giant planet systems from a large number of planetary embryos. Our simulations produced systems that are stable for at least a billion years and that exhibit a wide range of characteristics. Some of these systems are reminiscent of the outer solar system. The number of planets ranged from one to seven. Many systems contained only Uranus-mass objects. We constructed systems that were more compact than the outer solar system and systems that were much sparser, with planets on very eccentric orbits. Perhaps most surprisingly, some of the systems that we constructed were stable for at least a billion years despite undergoing macroscopic orbital changes on much shorter timescales.
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/1351
- Title:
- Outer satellites occultation predictions
- Short Name:
- J/MNRAS/462/1351
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gomes-Junior et al. (2015, Cat. J/A+A/580/A76) published 3613 positions for the 8 largest irregular satellites of Jupiter and 1787 positions for the largest irregular satellite of Saturn, Phoebe. These observations were made between 1995 and 2014 and have an estimated error of about 60 to 80 mas. Based on this set of positions, we derived new orbits for the eight largest irregular satellites of Jupiter: Himalia, Elara, Pasiphae, Carme, Lysithea, Sinope, Ananke and Leda. For Phoebe we updated the ephemeris from Desmars et al. (2013, Cat. J/A+A/553/A36) using 75% more positions than the previous one. Due to their orbital characteristics, it is common belief that the irregular satellites were captured by the giant planets in the early Solar System, but there is no consensus for a single model explaining where they were formed. Size, shape, albedo and composition would help to trace back their true origin, but these physical parameters are yet poorly known for irregular satellites. The observation of stellar occultations would allow for the determination of such parameters. Indeed Jupiter will cross the galactic plane in 2019-2020 and Saturn in 2018, improving a lot the chances of observing such events in the near future. Using the derived ephemerides and the UCAC4 catalogue we managed to identify 5442 candidate stellar occultations between January 2016 and December 2020 for the 9 satellites studied here. We discussed how the successful observation of a stellar occultation by these objects is possible and present some potential occultations.
- ID:
- ivo://CDS.VizieR/J/AJ/152/70
- Title:
- Outer Solar System Origins Survey (OSSOS). I.
- Short Name:
- J/AJ/152/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery, tracking, and detection circumstances for 85 trans-Neptunian objects (TNOs) from the first 42deg^2^ of the Outer Solar System Origins Survey. This ongoing r-band solar system survey uses the 0.9deg^2^ field of view MegaPrime camera on the 3.6m Canada-France-Hawaii Telescope. Our orbital elements for these TNOs are precise to a fractional semimajor axis uncertainty <0.1%. We achieve this precision in just two oppositions, as compared to the normal three to five oppositions, via a dense observing cadence and innovative astrometric technique. These discoveries are free of ephemeris bias, a first for large trans-Neptunian surveys. We also provide the necessary information to enable models of TNO orbital distributions to be tested against our TNO sample. We confirm the existence of a cold "kernel" of objects within the main cold classical Kuiper Belt and infer the existence of an extension of the "stirred" cold classical Kuiper Belt to at least several au beyond the 2:1 mean motion resonance with Neptune. We find that the population model of Petit et al. remains a plausible representation of the Kuiper Belt. The full survey, to be completed in 2017, will provide an exquisitely characterized sample of important resonant TNO populations, ideal for testing models of giant planet migration during the early history of the solar system.
- ID:
- ivo://CDS.VizieR/J/A+A/643/L10
- Title:
- Phoebe Spherical Harmonics decomposition
- Short Name:
- J/A+A/643/L10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Phoebe is an irregular satellite of Saturn, and its origin, from either between the orbits of the giant planets or the Kuiper Belt, is still uncertain. The extent of differentiation of its interior can potentially help inform its formation location because it is mainly determined by heat from 26-aluminium. The internal structure is reflected in the shape, assuming the body is relaxed to hydrostatic equilibrium. Although previous data analysis indicates Phoebe is close to hydrostatic equilibrium, its heavily cratered surface makes it difficult to tease out its low-order shape characteristics. This paper aims to extract Phoebe's global shape from the observations returned by the Cassini mission for comparison with uniform and stratified interior models under the assumption of hydrostatic equilibrium. The global shape is derived from fitting spherical harmonics and keeping only the low-degree harmonics that represent the shape underneath the heavily cratered surface. The hydrostatic theoretical model for shape interpretation is based on the Clairaut equation developed to the third order (although the second order is sufficient in this case). We show that Phoebe is differentiated with a mantle density between 1900 and 2400kg/m^3^. The presence of a porous surface layer further restricts the fit with the observed shape. This result confirms the earlier suggestion that Phoebe accreted with sufficient 26-aluminium to drive at least partial differentiation, favoring an origin with C-type asteroids.
- ID:
- ivo://CDS.VizieR/J/A+A/375/285
- Title:
- Photometric observations of 9 Near-Earth Objects
- Short Name:
- J/A+A/375/285
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new CCD observations of nine Near-Earth Asteroids carried out between February, 1999 and July, 2000. The bulk of the data was acquired through an R_C_ filter, while the minor planet 11405 was observed without filter. Data were obtained with the 1.23m telescope of the German-Spanish Astronomical Centre, Calar Alto; with the 0.60m telescope of the Konkoly Observatory and with the 0.28m telescope of the Szeged Observatory. We could determine synodic periods and amplitudes for 5 asteroids, 699: 3.3h, 0.18m; 1866: 2.7h, 0.12m; 1999 JD6: 7.68h, 1.2m ; 2000 GK137: 4.84h, 0.27m; 2000 NM: 9.24h, 0.30m. Based on observations taken at different phases, we could infer a phase parameter m of 0.018+/-0.005 for 1865 Cerberus. An epoch-method yielded a sideral period of 0.27024003(5) for this object with retrograde rotation. The remaining 3 objects have only partial coverage, thus no firm conclusion on their synodic period is possible.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A7
- Title:
- Photometry and models of long-period asteroids
- Short Name:
- J/A+A/610/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The available set of spin and shape modelled asteroids is strongly biased against slowly rotating targets and those with low lightcurve amplitudes. This is due to the observing selection effects. As a consequence, the current picture of asteroid spin axis distribution, rotation rates, radiometric properties, or aspects related to the object's internal structure might be affected too. To counteract these selection effects, we are running a photometric campaign of a large sample of main belt asteroids omitted in most previous studies. Using least chi-squared fitting we determined synodic rotation periods and verified previous determinations. When a dataset for a given target was sufficiently large and varied, we performed spin and shape modelling with two different methods to compare their performance. We used the convex inversion method and the non-convex SAGE algorithm, applied on the same datasets of dense lightcurves. Both methods search for the lowest deviations between observed and modelled lightcurves, though using different approaches. Unlike convex inversion, the SAGE method allows for the existence of valleys and indentations on the shapes based only on lightcurves. We obtain detailed spin and shape models for the first five targets of our sample: (159) Aemilia, (227) Philosophia, (329) Svea, (478) Tergeste, and (487) Venetia. When compared to stellar occultation chords, our models obtained an absolute size scale and major topographic features of the shape models were also confirmed. When applied to thermophysical modelling (TPM), they provided a very good fit to the infrared data and allowed their size, albedo, and thermal inertia to be determined. Convex and non-convex shape models provide comparable fits to lightcurves. However, some non-convex models fit notably better to stellar occultation chords and to infrared data in sophisticated thermophysical modelling (TPM). In some cases TPM showed strong preference for one of the spin and shape solutions. Also, we confirmed that slowly rotating asteroids tend to have higher-than-average values of thermal inertia, which might be caused by properties of the surface layers underlying the skin depth.
- ID:
- ivo://CDS.VizieR/J/AJ/154/241
- Title:
- Photometry of a Kuiper Belt object: 2002 CC_249_
- Short Name:
- J/AJ/154/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Images of the Kuiper Belt object (126719) 2002 CC_249_ obtained in 2016 and 2017 using the 6.5 m Magellan-Baade Telescope and the 4.3 m Discovery Channel Telescope are presented. A light curve with a periodicity of 11.87+/-0.01 hr and a peak-to-peak amplitude of 0.79+/-0.04 mag is reported. This high amplitude double-peaked light curve can be due to a single elongated body, but it is best explained by a contact binary system from its U-/V-shaped light curve. We present a simple full-width-at-half-maximum test that can be used to determine if an object is likely a contact binary or an elongated object based on its light curve. Considering that 2002 CC_249_ is in hydrostatic equilibrium, a system with a mass ratio q_min_=0.6, and a density {rho}_min_=1 g/cm^3^, or less plausible a system with q_max_=1, and {rho}_max_=5 g/cm^3^ can interpret the light curve. Assuming a single Jacobi ellipsoid in hydrostatic equilibrium and an equatorial view, we estimate {rho}>=0.34 g/cm^3^, and a/b=2.07. Finally, we report a new color study showing that 2002 CC_249_ displays an ultra red surface characteristic of a dynamically Cold Classical trans-Neptunian object.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A102
- Title:
- Photometry of 16 Flora family asteroids
- Short Name:
- J/A+A/551/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is known that the Yarkovsky effect moves small asteroids to larger/smaller semimajor axes depending on their prograde/retrograde spins. The YORP effect influences asteroid spin periods and spin axis orientations so that they evolve in time. The alignment of the spin vectors and correlations of the spin rates, now known as Slivan states and observed among members of the Koronis family, are interpreted in terms of the YORP effect and spin-orbit resonances. Splitting asteroid families into prograde and retrograde groups has recently been proposed as a result of the Yarkovsky effect. Prograde and retrograde asteroids drift in different directions, and this has never been observed directly. The influence of the Yarkovsky and YORP effects should be observable among objects in asteroid families, especially in the Flora family, which lies close to the Sun and consists of many small objects. The Flora family asteroids were modelled using the lightcurve inversion technique. As a result the orientation of spin vectors, shapes, and sidereal periods of rotation were obtained.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A131
- Title:
- Photometry of 8 main belt asteroids
- Short Name:
- J/A+A/545/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The shapes and spin states of asteroids observed with photometric techniques can be reconstructed using the lightcurve inversion method. The resultant models can then be confirmed or exploited further by other techniques, such as adaptive optics, radar, thermal infrared, stellar occultations, or space probe imaging. During our ongoing work to increase the set of asteroids with known spin and shape parameters, there appeared a need for displaying the model plane-of-sky orientations for specific epochs to compare models from different techniques. It would also be instructive to be able to track how the complex lightcurves are produced by various asteroid shapes.
