- 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.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/507/495
- Title:
- Light curves of Datura and 2003 CL5 asteroids
- Short Name:
- J/A+A/507/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Research of asteroid families has been recently refreshed by the discovery of very young ones. These families are of great interest because they represent the product of their parent body fragmentation before orbital and physical evolutionary processes can change them. A cluster of seven objects around the largest body (1270) Datura is of particular interest because it has enough known members and resides in the inner part of the main asteroid belt, facilitating observations. We carried out photometric observations of the two largest members of the Datura family - asteroids (1270) Datura and (90265) 2003 CL5 - with the goal of inferring their physical parameters. We also used numerous astrometric observations of Datura-family members in the past few years to revisit the age of this cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/134/787
- Title:
- Light curves of dwarf plutonian planets
- Short Name:
- J/AJ/134/787
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I report new time-resolved light curves and determine the rotations and phase functions of several large Kuiper Belt objects, which includes the dwarf planet Eris (2003 UB313). Three of the new sample of 10 trans-Neptunian objects display obvious short-term periodic light curves.
- ID:
- ivo://CDS.VizieR/J/A+A/546/A72
- Title:
- Light curves of Flora region asteroids
- Short Name:
- J/A+A/546/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies have uncovered evidence that the statistical properties of asteroids' physical parameters are a fundamental source of information on the physics of their collisions and evolution. The analysis of the spin rates and spin vector distributions helps us to understand the role of various known and new effects. The alignment of spin vectors and the correlation of spin rates are for the first time observed for ten members of the Koronis family. These unexpected non-random orientations of the spin axes and correlations of the spin rates, now known as Slivan states are interpreted in terms of a YORP effect and spin-orbit resonances. To study non-gravitational-effects, there appears to be a need for new observational campaigns devoted to determining the physical parameters of the asteroid families. We analysed the photometric observations of the asteroids, which are the most efficient method of studying asteroid physical parameters.
- ID:
- ivo://CDS.VizieR/J/A+AS/112/125
- Title:
- Lightcurves of minor planets
- Short Name:
- J/A+AS/112/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 81 photometric lightcurve of 36 minor planets observed in the V and B bands at the ESO 50cm telescope at La Silla (Chile). These asteroids were selected preferentially in order to improve their ecliptic longitude coverage in view of pole determinations and lightcurve inversions. We also give some first photometric observations and/or rotational period for several asteroids.
- ID:
- ivo://CDS.VizieR/J/A+A/550/L11
- Title:
- Lightcurves of Near-Earth Asteroid 162173 (1999 JU3)
- Short Name:
- J/A+A/550/L11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-Earth asteroid (hereafter NEA) 162173 (1999 JU3) is a potential target of two asteroid sample return missions not only because of its accessibility but also because of the first C-type asteroid for exploration missions. The lightcurve related physical properties of this object were investigated during the 2011-2012 apparition. We aim to confirm the physical parameters useful for JAXAs Hayabusa 2 mission such as rotational period, absolute magnitude and phase function. Our data complement previous studies which did not cover low phase angles. With optical imagers and 1-2m class telescopes, we acquired the photometric data at different phase angles. We independently derived the rotational lightcurve and the phase curve of the asteroid.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A123
- Title:
- Lightcurves of Near-Earth Asteroid 3200 Phaethon
- Short Name:
- J/A+A/619/A123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The near-Earth asteroid 3200 Phaethon (1983 TB) is an attractive object not only from a scientific viewpoint but also because of JAXA's DESTINY+ target. The rotational lightcurve and spin properties were investigated based on the data obtained in the ground-based observation campaign of Phaethon. We aim to refine the lightcurves and shape model of Phaethon using all available lightcurve datasets obtained via optical observation, as well as our time-series observation data from the 2017 apparition. Using eight 1-2-m telescopes and an optical imager, we acquired the optical lightcurves and derived the spin parameters of Phaethon. We applied the lightcurve inversion method and SAGE (Shaping Asteroids with Genetic Evolution) algorithm to deduce the convex and non-convex shape model and pole orientations.
- ID:
- ivo://CDS.VizieR/J/A+A/511/A49
- Title:
- Lightcurves of 12 NEAs
- Short Name:
- J/A+A/511/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Very small asteroids (VSAs) are thought to be the building blocks of larger asteroids and, as such, are interesting to study. Many of these monolithic or deeply fractured objects display rapid rotations with periods as short as several minutes. Observations of such asteroids can reveal their spin limits, which can be related to the tensile strength of their interiors. The evolution of the spins of these objects is primarily shaped by the YORP effect, the theory of which needs comparison with observations. With the 10m SALT telescope, we observed VSAs belonging to near-Earth asteroids. The obtained lightcurves were used to derive synodical periods of rotation, amplitudes, and elongations of these bodies. Results for 14 rapidly rotating asteroids were reported in the first paper in this series. Here we show lightcurves of 2 fast rotators, 9 objects with periods >=1h, and a possible non-principal axis rotator. We also list negative detections that most probably indicate asteroids with long periods and/or low amplitudes. Combining our results with the data from the literature, we obtain a set of 79 near-Earth VSAs with a median period of 0.25h (15min). By adjusting the spin limits predicted by theory to those observations, we find tentative evidence that the tensile strengths of VSAs, after scaling them to the same size, are of the same order as the minimum tensile strengths of stony meteoroids that undergo fragmentation under the atmospheric load.
- ID:
- ivo://CDS.VizieR/J/A+A/509/A94
- Title:
- Lightcurves of 14 NEAs
- Short Name:
- J/A+A/509/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report first results from our extensive survey of the very small (H>21.5mag) near-Earth asteroids. Our aim was to obtain photometric lightcurves for these faint, fast moving objects and to measure their rotation periods and amplitudes of light variations. These parameters can be used to make statistical analysis of the still little known population of the smallest asteroids, test present theories of the YORP effect as well as to study their spin limits, which are connected with their internal structure. Due to the faintness of the targets and the expected short periods of rotation, observations were performed with the large, 10-m SALT telescope in SAAO (South Africa). For most asteroids, V filter images with exposure times of 5-60 seconds were obtained with the instrument's SALTICAM's CCD camera. Even though the non-sidereal tracking was not available, the SALTICAM's relatively large field-of-view of 8'x8' helped to perform the relative photometry of the fast-moving targets. The presented asteroids have synodic periods ranging from 77s to 44min, effective diameters from 21 to 94m, and significantly elongated shapes.
- ID:
- ivo://CDS.VizieR/J/A+A/508/451
- Title:
- Light curves of 5 Trans-Neptunian Objects
- Short Name:
- J/A+A/508/451
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Trans-Neptunian objects (TNOs) represent a new frontier in the study of our Solar System. In particular, the investigation of their rotational properties can provide important hints about their internal structure and collisional evolution. We expand the limited sample of TNOs with known rotation rates, and improve the knowledge of the physical nature of these bodies.
