- ID:
- ivo://CDS.VizieR/J/ApJS/219/27
- Title:
- Surveys of asteroid rotation periods using iPTF
- Short Name:
- J/ApJS/219/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two dedicated asteroid rotation-period surveys have been carried out in the R band with ~20 minute cadence using the intermediate Palomar Transient Factory (iPTF) during 2014 January 6-9 and February 20-23. The total survey area covered 174deg^2^ in the ecliptic plane. Reliable rotation periods for 1438 asteroids are obtained from a larger data set of 6551 mostly main-belt asteroids, each with >=10 detections. Analysis of 1751, PTF-based, reliable rotation periods clearly shows the spin barrier at ~2hr for rubble-pile asteroids. We found a new large super-fast rotator, 2005 UW163, and another five candidates as well. For asteroids of 3<D<15km, our spin-rate distribution shows a number decrease along with frequency after 5 rev/day, which is consistent with the results of the Asteroid Light Curve Database. The discrepancy between our work and that of Pravec et al. (update 2014 April 20) comes mainly from asteroids with {Delta}_m_<0.2mag, which could be the result of different survey strategies. For asteroids with D<3km, we see a significant number drop at f=6rev/day. The relatively short YORP effect timescale for small asteroids could have spun up those elongated objects to reach their spin-rate limit resulting in breakup to create such a number deficiency. We also see that the C-type asteroids show a smaller spin-rate limit than the S-type, which agrees with the general impression that C-type asteroids have a lower bulk density than S-type asteroids.
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- ID:
- ivo://CDS.VizieR/J/A+A/617/A12
- Title:
- Taxonomic classification of asteroids
- Short Name:
- J/A+A/617/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We tabulate the taxonomic classification of 18265 asteroids catalogued by MOVIS. A probabilistic method and the k-nearest neighbors (KNN k=3) algorithm are used to assign a taxonomic type for each object.
- ID:
- ivo://CDS.VizieR/J/AJ/151/11
- Title:
- Taxonomy of potentially hazardous asteroids
- Short Name:
- J/AJ/151/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Through their delivery of water and organics, near-Earth objects (NEOs) played an important role in the emergence of life on our planet. However, they also pose a hazard to the Earth, as asteroid impacts could significantly affect our civilization. Potentially hazardous asteroids (PHAs) are those that, in principle, could possibly impact the Earth within the next century, producing major damage. About 1600 PHAs are currently known, from an estimated population of 4700+/-1450. However, a comprehensive characterization of the PHA physical properties is still missing. Here we present spectroscopic observations of 14 PHAs, which we have used to derive their taxonomy, meteorite analogs, and mineralogy. Combining our results with the literature, we investigated how PHAs are distributed as a function of their dynamical and physical properties. In general, the ''carbonaceous'' PHAs seem to be particularly threatening, because of their high porosity (limiting the effectiveness of the main deflection techniques that could be used in space) and low inclination and minimum orbit intersection distance (MOID) with the Earth (favoring more frequent close approaches). V-type PHAs also present low MOID values, which can produce frequent close approaches (as confirmed by the recent discovery of a limited space weathering on their surfaces). We also identified those specific objects that deserve particular attention because of their extreme rotational properties, internal strength, or possible cometary nature. For PHAs and NEOs in general, we identified a possible anti-correlation between the elongation and the rotational period, in the range of P_rot_~5-80hr. This would be compatible with the behavior of gravity-dominated aggregates in rotational equilibrium. For periods >~80-90hr, such a trend stops, possibly under the influence of the YORP effect and collisions. However, the statistics is very low, and further observational and theoretical work is required to characterize such slow rotators.
- ID:
- ivo://CDS.VizieR/J/A+A/598/A63
- Title:
- 2015 TB145 light curve
- Short Name:
- J/A+A/598/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The near-Earth asteroid (NEA) 2015 TB145 had a very close encounter with Earth at 1.3 lunar distances on October 31, 2015. We obtained 3-band mid-infrared observations of this asteroid with the ESO VLT-VISIR instrument covering about 4 hours in total. We also monitored the visual lightcurve during the close-encounter phase. The NEA has a (most likely) rotation period of 2.939+/-0.005-hours and the visual lightcurve shows a peak-to-peak amplitude of about 0.12+/-0.02mag. A second rotation period of 4.779+/-0.012h, with an amplitude of the Fourier fit of 0.10+/-0.02mag, also seems compatible with the available lightcurve measurements. We estimate a V-R colour of 0.56+/-0.05mag from different entries in the MPC database. A reliable determination of the object's absolute magnitude was not possible. Applying different phase relations to the available R-/V-band observations produced H_R_=18.6mag (standard H-G calculations) or H_R_=19.2mag and H_V_=19.8mag (via the H-G_12_ procedure for sparse and low-quality data), with large uncertainties of about 1mag. We performed a detailed thermophysical model analysis by using spherical and partially also ellipsoidal shape models. The thermal properties are best explained by an equator-on (+/-~30{deg}) viewing geometry during our measurements with a thermal inertia in the range 250-700J/m^2^/s^0.5^/K (retrograde rotation) or above 500J/m^2^/s^0.5^/K (prograde rotation). We find that the NEA has a minimum size of about 625m, a maximum size of just below 700m, and a slightly elongated shape with a/b~1.1.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A134
- Title:
- The large TNO 2002 TC302
- Short Name:
- J/A+A/639/A134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On 28th January 2018, the large Trans-Neptunian Object 2002 TC_302_ occulted a m_v_~15.3 star with designation 593-005847 in the UCAC4 stellar catalog, corresponding to Gaia source 130957813463146112. Twelve positive occultation chords were obtained from Italy, France, Slovenia and Switzerland. Also, four negative detections were obtained near the north and south limbs. This represents the best observed stellar occultation by a TNO other than Pluto in terms of the number of chords published thus far. From the twelve chords, an accurate elliptical fit to the instantaneous projection of the body can be obtained, compatible with the near misses. The resulting ellipse has major and minor axes of 543+/-18km and 460+/-11km, respectively, with a position angle of 3+/-1 degrees for the minor axis. This information, combined with rotational light curves obtained with the 1.5-m telescope at Sierra Nevada Observatory and the 1.23-m telescope at Calar Alto observatory, allows us to derive possible three-dimensional shapes and density estimations for the body based on hydrostatic equilibrium assumptions. The effective diameter in equivalent area is around 84km smaller than the radiometrically derived diameter using thermal data from Herschel and Spitzer Space Telescopes. This might indicate the existence of an unresolved satellite of up to ~300km in diameter, to account for all the thermal flux, although the occultation and thermal diameters are compatible within their error bars given the considerable uncertainty of the thermal results. The existence of a potential satellite also appears to be consistent with other ground-based data presented here. From the effective occultation diameter combined with absolute magnitude measurements we derive a geometric albedo of 0.147+/-0.005, which would be somewhat smaller if 2002 TC_302_ has a satellite. The best occultation light curves do not show any signs of ring features or any signatures of a global atmosphere.
206. Themis Family
- ID:
- ivo://CDS.VizieR/J/A+AS/134/463
- Title:
- Themis Family
- Short Name:
- J/A+AS/134/463
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observational circumstances of 36 members of the Themis family observed at the 1.52m telescope of ESO (La Silla) under the agreement with the CNPq-Observatorio Nacional (Brazil). File Summary:
- ID:
- ivo://CDS.VizieR/J/AJ/156/60
- Title:
- Thermal model fits for short-arc NEOs with NEOWISE
- Short Name:
- J/AJ/156/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Automated asteroid detection routines set requirements on the number of detections, signal-to-noise ratio, and the linearity of the expected motion in order to balance completeness, reliability, and time delay after data acquisition when identifying moving object tracklets. However, when the full-frame data from a survey are archived, they can be searched later for asteroids that were below the initial detection thresholds. We have conducted such a search of the first three years of the reactivated Near-Earth Object Wide-field Infrared Survey Explorer data, looking for near-Earth objects discovered by ground-based surveys that have previously unreported thermal infrared data. Using these measurements, we can then perform thermal modeling to measure the diameters and albedos of these objects. We present new physical properties for 116 Near-Earth Objects found in this search.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A139
- Title:
- Thermal properties of slow asteroids
- Short Name:
- J/A+A/625/A139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Earlier work suggests that slowly rotating asteroids should have higher thermal inertias than faster rotators because the heat wave penetrates deeper into the subsurface. However, thermal inertias have been determined mainly for fast rotators due to selection effects in the available photometry used to obtain shape models required for thermophysical modelling (TPM). Our aims are to mitigate these selection effects by producing shape models of slow rotators, to scale them and compute their thermal inertia with TPM, and to verify whether thermal inertia increases with the rotation period. To decrease the bias against slow rotators, we conducted a photometric observing campaign of main-belt asteroids with periods longer than 12h, from multiple stations worldwide, adding in some cases data from WISE and Kepler space telescopes. For spin and shape reconstruction we used the lightcurve inversion method, and to derive thermal inertias we applied a thermophysical model to fit available infrared data from IRAS, AKARI, and WISE. We present new models of 11 slow rotators that provide a good fit to the thermal data. In two cases, the TPM analysis showed a clear preference for one of the two possible mirror solutions. We derived the diameters and albedos of our targets in addition to their thermal inertias, which ranged between 3_-3_^+33^ and 45_-30_^+60^J/m^2^/s^1/2^/K. Together with our previous work, we have analysed 16 slow rotators from our dense survey with sizes between 30 and 150 km. The current sample thermal inertias vary widely, which does not confirm the earlier suggestion that slower rotators have higher thermal inertias.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A109
- Title:
- The SkyMapper DR3 SSOs
- Short Name:
- J/A+A/658/A109
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The populations of small bodies of the Solar System (asteroids, comets, and Kuiper Belt objects) are used to constrain the origin and evolution of the Solar System. Their orbital distribution and composition distribution are both required to track the dynamical pathway from their formation regions to their current locations. We aim to increase the sample of Solar System objects (SSOs) that have multifilter photometry and compositional taxonomy. Methods. We searched for moving objects in the SkyMapper Southern Survey. We used the predicted SSO positions to extract photometry and astrometry from the SkyMapper frames. We then applied a suite of filters to clean the catalog from false-positive detections. We finally used the near-simultaneous photometry to assign a taxonomic class to objects. We release a catalog of 880,528 individual observations, consisting of 205515 known and unique SSOs. The catalog completeness is estimated to be about 97% down to V=18mag and the purity is higher than 95% for known SSOs. The near-simultaneous photometry provides either three, two, or a single color that we use to classify 117356 SSOs with a scheme consistent with the widely used Bus-DeMeo taxonomy. The present catalog contributes significantly to the sample of asteroids with known surface properties (about 40% of main-belt asteroids down to an absolute magnitude of 16). We will release more observations of SSOs with future SkyMapper data releases.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A106
- Title:
- Time-series photometry of 2012 DA14
- Short Name:
- J/A+A/559/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The object 2012 DA14 is a near-Earth asteroid with a size of several tens of meters. It had approached closely the Earth on 15 February 2013 UT, providing an opportunity for precise measurements of this tiny asteroid. The solar phase angle of 2012 DA14 had varied widely around its closest approach but was almost constant during the following night. We performed time-series photometric observations on those two nights to determine the rotational properties and phase effect. The observations were carried out using the 0.55-m telescope at Saitama University, Japan. The R-band images were obtained continuously over a 2h period at the closest approach and for about 5h on the next night.
