- ID:
- ivo://CDS.VizieR/J/A+A/561/A37
- Title:
- Prediction of stellar occultations 2012.5-2014
- Short Name:
- J/A+A/561/A37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The prediction tables of stellar occultations by 5 Centaurs and 34 TNOs (referred simply as TNOs hereafter) for the period 2012.5-2014 were built to support the investigation of the physical properties of (8405) Asbolus, (24835) 1995 SM55, (10199) Chariklo, (26375) 1999 DE9, (47171) 1999 TC36, (38628) Huya, (54598) Bienor, (55565) 2002 AW197, (55576) Amycus, (83982) Crantor, (119951) 2002 KX14, (307261) 2002 MS4, (84522) 2002 TC302, (55637) 2002 UX25, (55638) 2002 VE95, (119979) 2002 WC19, (120132) 2003 FY128, (174567) 2003 MW12, (120178) 2003 OP32, 2003 UZ413, (84922) 2003 VS2, (90568) 2004 GV9, 2004 NT33, (175113) 2004 PF115, (120347) Salacia, (120348) 2004 TY364, (144897) 2004 UX10, 2005 CC79 (2011 FX62), (303775) 2005 QU182, (145451) 2005 RM43, (145452) 2005 RN43, (145453) 2005 RR43, (202421) 2005 UQ513, 2007 JH43, (278361) 2007 JJ43, (225088) 2007 OR10, (229762) 2007 UK126, 2008 OG19, and 2010 EK139 for this period. These objects are important to understand the structure, origin, and evolution of the outer solar system. Our goal was to derive precise predictions. With this aim, we constructed astrometric star catalogues in the UCAC4 system covering their sky paths. For that, we carried out during 2011-2013 an observational program at the ESO2p2/WFI instrument covering the sky path of these 39 TNOs for the period 2012.5-2014. We made the astrometry of 550 GB of images with the Platform for Reduction of Astronomical Images Automatically (PRAIA). By relatively simple astrometric techniques, we treated the overlapping observations and derived a field distortion pattern for the WFI mosaic of CCDs to within 50mas precision. The catalogue star positions were obtained in the UCAC4 frame with uncertainties of 40mas for stars up to magnitude completeness (about R=19). New stellar proper motions were also determined with 2MASS and the USNO B1.0 catalogue positions as first epoch. The catalogues for all TNOs contain in all more than 12.4 million entries, covering the sky paths of the objects with 30 arcmin width. The magnitude completeness is about R=19 with a limit about R=21. Ephemeris offsets with about 10mas to 100mas precision were applied for each TNO orbit to improve the predictions. They were obtained during 2011-2013 from a parallel observational campaign carried out with telescope diameters from 0.6m to 2.2m. The 7343 candidate stars listed in the prediction tables were searched using a proximity radius of 650mas with the geocentric apparent orbit (corrected by ephemeris offsets) of the body considered. This radius is a little more than seven times the apparent radius of a body with Pluto's size (50mas) plus the apparent Earth radius (285 mas) as projected in the sky plane at 31AU (about the Pluto-Earth distance for 2008-2015). No threshold in R magnitude was used in the search for candidates, as relatively faint R objects may turn out to be bright infrared stars, perfect targets for the SOFIA observatory and for ground-based instruments well equipped with J, H, or K band detectors (J, H, and K magnitudes are promptly available in the tables if the star belongs to the 2MASS). Besides, events may be also favoured by slow shadow speeds of less than 20km/s. Also, no constraint on a geographic place was applied, as in principle SOFIA observations can be done from any sub-solar point on Earth. Events in daylight at sub-planet point were not excluded either, as they could yet be observable in the dark, right above the horizon, from places near the Earth terminator. We furnish here prediction tables for future and also for past stellar occultations covering the sky paths between 2012.5-2014. The importance of predictions for occultations still to come is obvious. But the predictions of past occultations are also useful for at least three reasons. First, they can be used by anyone as reference for ongoing fittings of light curves of recent past observed events. Second, they serve to derive ephemeris drifts by comparing expected and observed central instants and C/A values. Finally, they can be used as an external check for the accuracy and precision of our prediction tables. In all, for R=19 stars (catalogue magnitude completeness) and 40mas errors in the WFI positions, we may assume a bulk error of about 80mas for C/A, dominated by the ephemeris offsets errors of about 70mas. For about 40AU, this implies a shadow path uncertainty over the Earth of the order of 2300km. If the ephemeris offsets can be well determined to within 30mas precision, then a bulk error of 50mas in C/A can be achieved, leading to a precision of about 1400km for the WFI occultation path predictions. Thus, the probability of actually observing the occultation is not as high as hoped, but not despairingly small, especially if the event occurs above a dense, populated region in terms of astronomers, including amateurs, with access to telescopes.
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- ID:
- ivo://CDS.VizieR/J/A+A/541/A142
- Title:
- Prediction of stellar occultations 2008-2015
- Short Name:
- J/A+A/541/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The prediction tables of stellar occultations by Eris, Haumea, Makemake, Quaoar, Orcus, Sedna, Varuna, Ixion, 2002TX300 and 2003AZ84 for 2008-2015 were built to support the investigation of the physical properties of large transneptunian objects - keystones in the study of structure, origin and evolution of the Solar System. Our goal was to derive precise, astrometric predictions. With this aim, we constructed astrometric star catalogs in the UCAC2 system covering their sky paths. For that, we have carried out in 2007-2009 an observational program at the ESO2p2/WFI instrument covering the sky path of these 10 large TNOs for the 2008-2015. We made the astrometry of 316 GB of images with the Platform for Reduction of Astronomical Images Automatically (PRAIA). By relatively simple astrometric techniques, we treated the overlapping observations and derived a field distortion pattern for the WFI mosaic of CCDs to within 50 mas precision. The catalog star positions were obtained in the UCAC2 frame with errors of 40mas for stars up to magnitude completeness (about R=19). New stellar proper motions were also determined with 2MASS and the USNO B1.0 catalog positions as first epoch. The catalogs of all TNOs contain in all more than 5.35 million stars with proper motions, covering the sky paths of the objects with 30 arcmin width. The magnitude completeness is about R=19 with a limit about R=21. Ephemeris offsets with about 50mas to 100mas precision were applied for each TNO orbit to improve the predictions. They were obtained during 2007-2010 from a parallel observational campaign carried out with 0.6m to 2.2m size telescopes. The 2718 candidate stars listed in the prediction tables were searched using a proximity radius of 335mas with the geocentric apparent orbit (corrected by ephemeris offsets) of the body considered. This radius is about the apparent radius of a body with Pluto's size (50mas) plus the apparent Earth radius (285mas) as projected in the sky plane at 31AU (about the Pluto-Earth distance for 2008-2015). No threshold in R magnitude was used in the search for candidates, as relatively faint R objects may turn out to be bright infrared stars, perfect targets for the SOFIA observatory and for ground-based instruments well equipped with H, J or K band detectors (H, J and K magnitudes are promptly available in the tables if the star belongs to the 2MASS). Besides, events may be also favored by slow shadow speeds of less than 20km/s. Also, no constraint on a geographic place was applied, as in principle SOFIA observations can be done from any sub-solar point on Earth. Events in daylight at sub-planet point were not excluded either, as they could yet be observable in the dark, right above the horizon, from places near the Earth terminator. We furnish here prediction tables for future and also for past stellar occultations covering the sky paths between 2008-2015. The importance of predictions for occultations still to come is obvious. But the predictions of past occultations are also useful for at least three reasons. First, they can be used by anyone as reference for ongoing fittings of light curves of recent past observed events. Second, they serve to derive ephemeris drifts by comparing expected and observed central instants and C/A values. Finally, they can be used as an external check for the accuracy and precision of our prediction tables. In all, for R=19 stars (catalog magnitude completeness) and 40mas errors in the WFI positions, we may assume a bulk error of about 80mas for C/A, dominated by the ephemeris offsets errors of about 70mas. For about 40AU, this implies a shadow path uncertainty over the Earth of the order of 2300km. If the ephemeris offsets can be well determined to within 30mas precision, then a bulk error of 50mas in C/A can be achieved, leading to a precision of about 1400km for the WFI occultation path predictions. Thus, the probability of actually observing the occultation is not as high as hoped, but not despairingly small, especially if the event occurs above a dense, populated region in terms of astronomers, including amateurs.
- ID:
- ivo://CDS.VizieR/J/ApJ/789/151
- Title:
- Properties of asteroids in comet-like orbits
- Short Name:
- J/ApJ/789/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated the population of asteroids in comet-like orbits using available asteroid size and albedo catalogs of data taken with the Infrared Astronomical Satellite, AKARI, and the Wide-field Infrared Survey Explorer on the basis of their orbital properties (i.e., the Tisserand parameter with respect to Jupiter, T_J_, and the aphelion distance, Q). We found that (1) there are 123 asteroids in comet-like orbits by our criteria (i.e., Q > 4.5 AU and T_J_< 3), (2) 80% of them have low albedo, p_v_< 0.1, consistent with comet nuclei, (3) the low-albedo objects among them have a size distribution shallower than that of active comet nuclei, that is, the power index of the cumulative size distribution is around 1.1, and (4) unexpectedly, a considerable number (i.e., 25 by our criteria) of asteroids in comet-like orbits have high albedo, p_v_> 0.1. We noticed that such high-albedo objects mostly consist of small (D < 3 km) bodies distributed in near-Earth space (with perihelion distance of q < 1.3 AU). We suggest that such high-albedo, small objects were susceptible to the Yarkovsky effect and drifted into comet-like orbits via chaotic resonances with planets.
- ID:
- ivo://CDS.VizieR/J/AJ/151/164
- Title:
- Properties of asteroids in Karin cluster
- Short Name:
- J/AJ/151/164
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Karin cluster is a young asteroid family thought to have formed only ~5.75Myr ago. The young age can be demonstrated by numerically integrating the orbits of Karin cluster members backward in time and showing the convergence of the perihelion and nodal longitudes (as well as other orbital elements). Previous work has pointed out that the convergence is not ideal if the backward integration only accounts for the gravitational perturbations from the solar system planets. It improves when the thermal radiation force known as the Yarkovsky effect is accounted for. This argument can be used to estimate the spin obliquities of the Karin cluster members. Here we take advantage of the fast growing membership of the Karin cluster and show that the obliquity distribution of diameter D~1-2km Karin asteroids is bimodal, as expected if the YORP effect acted to move obliquities toward extreme values (0{deg} or 180{deg}). The measured magnitude of the effect is consistent with the standard YORP model. The surface thermal conductivity is inferred to be 0.07-0.2W/m/K (thermal inertia ~300--500J/m^2^/K/s^1/2^). We find that the strength of the YORP effect is roughly ~0.7 of the nominal strength obtained for a collection of random Gaussian spheroids. These results are consistent with a surface composed of rough, rocky regolith. The obliquity values predicted here for 480 members of the Karin cluster can be validated by the light-curve inversion method.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A87
- Title:
- Properties of slowly rotating asteroids.
- Short Name:
- J/A+A/654/A87
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Recent results for asteroid rotation periods from the TESS mission showed how strongly previous studies have underestimated the number of slow rotators, revealing the importance of studying those targets. For most slowly rotating asteroids (those with P>12h), no spin and shape model is available because of observation selection effects. This hampers determination of their thermal parameters and accurate sizes. Also, it is still unclear whether signatures of different surface material properties can be seen in thermal inertia determined from mid-infrared thermal flux fitting. We continue our campaign in minimising selection effects among main belt asteroids. Our targets are slow rotators with low light-curve amplitudes. Our goal is to provide their scaled spin and shape models together with thermal inertia, albedo, and surface roughness to complete the statistics. Rich multi-apparition datasets of dense light curves are supplemented with data from Kepler and TESS spacecrafts. In addition to data in the visible range, we also use thermal data from infrared space observatories (mainly IRAS, Akari and WISE) in a combined optimisation process using the Convex Inversion Thermophysical Model. This novel method has so far been applied to only a few targets, and therefore in this work we further validate the method itself. We present the models of 16 slow rotators, including two updated models. All provide good fits to both thermal and visible data.The obtained sizes are on average accurate at the 5% precision level, with diameters found to be in the range from 25 to 145km. The rotation periods of our targets range from 11 to 59h, and the thermal inertia covers a wide range of values, from 2 to <400J/m^2^/s^1/2^/K, not showing any correlation with the period. With this work we increase the sample of slow rotators with reliable spin and shape models and known thermal inertia by 40%. The thermal inertia values of our sample do not display a previously suggested increasing trend with rotation period, which might be due to their small skin depth.
- ID:
- ivo://CDS.VizieR/J/AJ/159/25
- Title:
- PS1 light curves and rotation periods of new asteroids
- Short Name:
- J/AJ/159/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The intranight trajectories of asteroids can be approximated by straight lines, and so are their intranight detections. Therefore, the Hough transform, a line detecting algorithm, can be used to connect the line-up detections to find asteroids. We applied this algorithm to a high-cadence Pan-STARRS 1 (PS1) observation, which was originally designed to collect asteroid light curves for rotation period measurements. The algorithm recovered most of the known asteroids in the observing fields and, moreover, discovered 3574 new asteroids with magnitude mainly of 21.5<w_p1_<22.5mag. This magnitude range is equivalent to subkilometer main-belt asteroids (MBAs), which usually lack rotation period measurements due to their faintness. Using the light curves of the 3574 new asteroids, we obtained 122 reliable rotation periods, of which 13 are super-fast rotators (SRFs; i.e., rotation period of <2hr). The required cohesion to survive these SFRs range from tens to thousands of Pa, a value consistent with the known SFRs and the regolith on the Moon and Mars. The higher chance of discovering SFRs here suggests that subkilometer MBAs probably harbor more SFRs.
177. (16) Psyche images
- ID:
- ivo://CDS.VizieR/J/A+A/619/L3
- Title:
- (16) Psyche images
- Short Name:
- J/A+A/619/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroid (16) Psyche is the target of the NASA Psyche mission. It is considered one of the few main-belt bodies that could be an exposed proto-planetary metallic core and that would thus be related to iron meteorites. Such an association is however challenged by both its near- and mid-infrared spectral properties and the reported estimates of its density. Here, we aim to refine the density of (16) Psyche to set further constraints on its bulk composition and determine its potential meteoritic analog. We observed (16) Psyche with ESO VLT/SPHERE/ZIMPOL as part of our large program (ID 199.C-0074). We used the high angular resolution of these observations to refine Psyche's three-dimensional (3D) shape model and subsequently its density when combined with the most recent mass estimates. In addition, we searched for potential companions around the asteroid. We derived a bulk density of 3.99+/-0.26g/cm^3^ for Psyche. While such density is incompatible at the 3-sigma level with any iron meteorites (~7.8g/cm^3^), it appears fully consistent with that of stony-iron meteorites such as mesosiderites (density ~4.25g/cm^3^). In addition, we found no satellite in our images and set an upper limit on the diameter of any non-detected satellite of 1460+/-200m at 150km from Psyche (0.2%xR_Hill_, the Hill radius) and 800+/-200m at 2000km (3%xRHill). Considering that the visible and near-infrared spectral properties of mesosiderites are similar to those of Psyche, there is merit to a long-published initial hypothesis that Psyche could be a plausible candidate parent body for mesosiderites.
- ID:
- ivo://CDS.VizieR/J/A+A/638/L15
- Title:
- (16) Psyche. VLT/SPHERE images and shape models
- Short Name:
- J/A+A/638/L15
- Date:
- 23 Mar 2022
- Publisher:
- CDS
- Description:
- Asteroid (16) Psyche is the largest M-type asteroid in the main belt and the target of the NASA Psyche mission. It is also the only asteroid of this size (D>200km) known to be metal rich. Although various hypotheses have been proposed to explain the rather unique physical properties of this asteroid, a perfect understanding of its formation and bulk composition is still missing. We aim to refine the shape and bulk density of (16) Psyche and to perform a thorough analysis of its shape to better constrain possible formation scenarios and the structure of its interior. We obtained disk-resolved VLT/SPHERE/ZIMPOL images acquired within our ESO large program (ID 199.C-0074), which complement similar data obtained in 2018. Both data sets offer a complete coverage of Psyche's surface. These images were used to reconstruct the three-dimensional (3D) shape of Psyche with two independent shape modeling algorithms (MPCD and ADAM). A shape analysis was subsequently performed, including a comparison with equilibrium figures and the identification of mass deficit regions. Our 3D shape along with existing mass estimates imply a density of 4.20+/-0.60g/cm^3, which is so far the highest for a solar system object following the four telluric planets. Furthermore, the shape of Psyche presents small deviations from an ellipsoid, that is, prominently three large depressions along its equator. The flatness and density of Psyche are compatible with a formation at hydrostatic equilibrium as a Jacobi ellipsoid with a shorter rotation period of ~3h. Later impacts may have slowed down Psyche's rotation, which is currently ~4.2h, while also creating the imaged depressions. Our results open the possibility that Psyche acquired its primordial shape either after a giant impact while its interior was already frozen or while its interior was still molten owing to the decay of the short-lived radionuclide ^26^Al.
- ID:
- ivo://CDS.VizieR/I/321
- Title:
- Pulkovo SMP Photographic Catalogue
- Short Name:
- I/321
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of new reduction of 1545 photographic observations of 14 selected asteroids' obtained with Normal Astrograph of Pulkovo observatory from 1948 to 1990 years presented. Photographic plates, stored in observatory's archive, was digitized using consumer flatbed scanner with special designed technique. The accuracy of measured photoplates was performed. The UCAC3 was used as reference catalog. The analysis of instrumental systematic effects, revealing in common distortion and magnitude equation, was performed and taken into account. The equatorial coordinates of 1378 single observations of selected asteroids was obtained and was made their comparison with results of reduction of this material obtained earlier. 1475 positions of stars with large proper motions from LSPM catalog was measured among background objects.
- ID:
- ivo://CDS.VizieR/J/other/PSS/134.96
- Title:
- 2007-2016 Pulkovo Uranian satellites obs.
- Short Name:
- J/other/PSS/134.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the observations of the Uranian satellites made with the 26-inch refractor at the Pulkovo Observatory in 2007-2016. During this time we got 17 normal positions of Ariel, 43 normal positions of Umbriel, 112 normal positions of Titania and 122 normal positions of Oberon. The observations were performed every year from the end of august to the beginning of January. Our results show a good quality of contemporary theories of Uranian satellites' and planets' motion. Published positions of the Uranian satellites can be useful for construction of future theories. Almost 7000 CCD frames were analyzed and reduced using the UCAC4 catalog. Observation processing and coordinate measurement were performed with the IZMCCD software package (izmccd.puldb.ru). Special approach was used to eliminate a scattered halo caused by the bright planet.
