- ID:
- ivo://CDS.VizieR/J/AJ/152/63
- Title:
- NEOWISE reactivation mission: 2nd yr data
- Short Name:
- J/AJ/152/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within +/-~20% and +/-~40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100m), and have low albedos.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/814/117
- Title:
- NEOWISE Reactivation mission: 1st yr data
- Short Name:
- J/ApJ/814/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present preliminary diameters and albedos for 7956 asteroids detected in the first year of the NEOWISE Reactivation mission. Of those, 201 are near-Earth asteroids and 7755 are Main Belt or Mars-crossing asteroids. 17% of these objects have not been previously characterized using the Near-Earth Object Wide-field Infrared Survey Explorer, or "NEOWISE" thermal measurements. Diameters are determined to an accuracy of ~20% or better. If good-quality H magnitudes are available, albedos can be determined to within ~40% or better.
- ID:
- ivo://CDS.VizieR/J/AJ/154/168
- Title:
- NEOWISE: thermal model fits for NEOs and MBAs
- Short Name:
- J/AJ/154/168
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Near-Earth ObjectWide-field Infrared Survey Explorer (NEOWISE) reactivation mission has completed its third year of surveying the sky in the thermal infrared for near-Earth asteroids and comets. NEOWISE collects simultaneous observations at 3.4 and 4.6 {mu}m of solar system objects passing through its field of regard. These data allow for the determination of total thermal emission from bodies in the inner solar system, and thus the sizes of these objects. In this paper, we present thermal model fits of asteroid diameters for 170 NEOs and 6110 Main Belt asteroids (MBAs) detected during the third year of the survey, as well as the associated optical geometric albedos. We compare our results with previous thermal model results from NEOWISE for overlapping sample sets, as well as diameters determined through other independent methods, and find that our diameter measurements for NEOs agree to within 26% (1{sigma}) of previously measured values. Diameters for the MBAs are within 17% (1{sigma}). This brings the total number of unique near-Earth objects characterized by the NEOWISE survey to 541, surpassing the number observed during the fully cryogenic mission in 2010.
124. New asteroid models
- ID:
- ivo://CDS.VizieR/J/A+A/620/A91
- Title:
- New asteroid models
- Short Name:
- J/A+A/620/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In addition to stellar data, Gaia Data Release 2 (DR2) also contains accurate astrometry and photometry of about 14000 asteroids covering 22 months of observations. We used Gaia asteroid photometry to reconstruct rotation periods, spin axis directions, and the coarse shapes of a subset of asteroids with enough observations. One of our aims was to test the reliability of the models with respect to the number of data points and to check the consistency of these models with independent data. Another aim was to produce new asteroid models to enlarge the sample of asteroids with known spin and shape. We used the lightcurve inversion method to scan the period and pole parameter space to create final shape models that best reproduce the observed data. To search for the sidereal rotation period, we also used a simpler model of a geometrically scattering triaxial ellipsoid. By processing about 5400 asteroids with at least ten observations in DR2, we derived models for 173 asteroids, 129 of which are new. Models of the remaining asteroids were already known from the inversion of independent data, and we used them for verification and error estimation. We also compared the formally best rotation periods based on Gaia data with those derived from dense lightcurves. We show that a correct rotation period can be determined even when the number of observations N is less than 20, but the rate of false solutions is high. For N>30, the solution of the inverse problem is often successful and the parameters are likely to be correct in most cases. These results are very promising because the final Gaia catalogue should contain photometry for hundreds of thousands of asteroids, typically with several tens of data points per object, which should be sufficient for reliable spin reconstruction.
- ID:
- ivo://CDS.VizieR/J/AJ/152/221
- Title:
- New extreme trans-Neptunian objects
- Short Name:
- J/AJ/152/221
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are performing a wide and deep survey for extreme distant solar system objects. Our goal is to understand the high-perihelion objects Sedna and 2012 VP113 and determine if an unknown massive planet exists in the outer solar system. The discovery of new extreme objects from our survey of some 1080 square degrees of sky to over 24th magnitude in the r-band are reported. Two of the new objects, 2014 SR349 and 2013 FT28, are extreme detached trans-Neptunian objects, which have semimajor axes greater than 150 au and perihelia well beyond Neptune (q>40au). Both new objects have orbits with arguments of perihelia within the range of the clustering of this angle seen in the other known extreme objects. One of these objects, 2014 SR349, has a longitude of perihelion similar to the other extreme objects, but 2013 FT28 is about 180{deg} away or anti-aligned in its longitude of perihelion. We also discovered the first outer Oort Cloud object with a perihelion beyond Neptune, 2014 FE72. We discuss these and other interesting objects discovered in our ongoing survey. All the high semimajor axis (a>150au) and high-perihelion (q>35au) bodies follow the previously identified argument of perihelion clustering as first reported and explained as being from an unknown massive planet in 2014 by Trujillo & Sheppard, which some have called Planet X or Planet Nine. With the discovery of 2013 FT28 on the opposite side of the sky, we now report that the argument of perihelion is significantly correlated with the longitude of perihelion and orbit pole angles for extreme objects and find there are two distinct extreme clusterings anti-aligned with each other. This previously unnoticed correlation is further evidence of an unknown massive planet on a distant eccentric inclined orbit, as extreme eccentric objects with perihelia on opposite sides of the sky (180{deg} longitude of perihelion differences) would approach the inclined planet at opposite points in their orbits, thus making the extreme objects prefer to stay away from opposite ecliptic latitudes to avoid the planet (i.e., opposite argument of perihelia or orbit pole angles).
- ID:
- ivo://CDS.VizieR/J/ApJ/791/121
- Title:
- NIR albedos of main-belt asteroids
- Short Name:
- J/ApJ/791/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present revised near-infrared albedo fits of 2835 main-belt asteroids observed by WISE/NEOWISE over the course of its fully cryogenic survey in 2010. These fits are derived from reflected-light near-infrared images taken simultaneously with thermal emission measurements, allowing for more accurate measurements of the near-infrared albedos than is possible for visible albedo measurements. Because our sample requires reflected light measurements, it undersamples small, low-albedo asteroids, as well as those with blue spectral slopes across the wavelengths investigated. We find that the main belt separates into three distinct groups of 6%, 16%, and 40% reflectance at 3.4 {mu}m. Conversely, the 4.6 {mu}m albedo distribution spans the full range of possible values with no clear grouping. Asteroid families show a narrow distribution of 3.4 {mu}m albedos within each family that map to one of the three observed groupings, with the (221) Eos family being the sole family associated with the 16% reflectance 3.4 {mu}m albedo group. We show that near-infrared albedos derived from simultaneous thermal emission and reflected light measurements are important indicators of asteroid taxonomy and can identify interesting targets for spectroscopic follow-up.
- ID:
- ivo://CDS.VizieR/J/AJ/135/55
- Title:
- NIR spectra of Centaurs and Kuiper Belt objects
- Short Name:
- J/AJ/135/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here an extensive survey of near-infrared (NIR) spectra of Kuiper belt objects (KBOs) and Centaurs taken with the Keck I Telescope. We find that most spectra in our sample are well characterized by a combination of water ice and a featureless continuum. A comparative analysis reveals that the NIR spectral properties have little correlation to the visible colors or albedo, with the exception of the fragment KBOs produced from the giant impact on 2003 E
- ID:
- ivo://CDS.VizieR/J/A+A/646/A182
- Title:
- Non-gravitational effects in retrograde orbits
- Short Name:
- J/A+A/646/A182
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dynamical studies of asteroid populations in retrograde orbits, i.e. with orbital inclinations greater than 90 degrees, are interesting because the origin of such orbits is still unexplained. Generally, the retrograde asteroids population includes mostly Centaurs and transneptunian objects (TNOs). A special case is the Near Earth Object (343158) 2009 HC82 from the Apollo group. Another interesting object is the comet 333P/LINEAR, which for several years was considered as the second retrograde object approaching Earth. One more comet in retrograde orbit, 161P Hartley/IRAS appears to be an object of similar type. Thanks to the large amount of observational data for these two comets, we tested various models of cometary non-gravitational forces applied to their dynamics. The goal was to estimate which of non-gravitational perturbations could affect the stability of retrograde bodies. In principle, we study the local stability by measuring the divergence of nearby orbits. We have numerically determined Lyapunov chaotic indicators (LCI) and the associated Lyapunov times (LT). This time, our calculations of these parameters were extended by more advanced models of non-gravitational perturbations (i.e. Yarkovsky drift and in selected cases cometary forces). This allowed estimating the chaos in the Lyapunov sense. We found that the Yarkovsky effect for obliquities of gamma=0{deg} and gamma=180{deg} can change LT substantially. In most cases, for the prograde rotation, we received more stable solutions. Moreover, we confirmed the role of retrograde resonances in this process. Additionally, the studied cometary effects also significantly influence the long-term behaviour of the selected comets. LT can reach values from 100 to over 1000 years. All results indicate that the use of models with non-gravitational effects for retrograde bodies is clearly justified.
- ID:
- ivo://CDS.VizieR/J/AJ/159/264
- Title:
- Observation of 10 Vesta asteroids with WISE/NEOWISE
- Short Name:
- J/AJ/159/264
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we investigate the size, thermal inertia, surface roughness, and geometric albedo of 10 Vesta family asteroids using the Advanced Thermophysical Model (ATM), based on the thermal-infrared data acquired by mainly NASA's Wide-field Infrared Survey Explorer (WISE). Here, we show that the average thermal inertia and geometric albedo of the investigated Vesta family members are 42J/m^2^/s^1/2^/K and 0.314, respectively, where the derived effective diameters are less than 10km. Moreover, the family members have a relatively low roughness fraction on their surfaces. The similarity in thermal inertia and geometric albedo among the V-type Vesta family members may reveal their close connection in origin and evolution. As the fragments of the cratering event of Vesta, the family members may have undergone a similar evolutionary process, thereby leading to very close thermal properties. Finally, we estimate their regolith grain sizes with different volume filling factors.
- ID:
- ivo://CDS.VizieR/J/ApJ/720/1691
- Title:
- Observations of the distant Kuiper belt
- Short Name:
- J/ApJ/720/1691
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a wide-field survey using the 1.2m Samuel Oschin Telescope at Palomar Observatory. This survey was designed to find the most distant members of the Kuiper Belt and beyond. We searched ~12000deg^2^ down to a mean limiting magnitude of 21.3 in R. A total number of 52 Kuiper Belt objects and Centaurs have been detected, 25 of which were discovered in this survey. Except for the redetection of Sedna, no additional Sedna-like bodies with perihelia greater than 45AU were detected despite sensitivity out to distances of 1000AU. We discuss the implications for a distant Sedna-like population beyond the Kuiper Belt, focusing on the constraints we can place on the embedded stellar cluster environment the early Sun may be have been born in, where the location and distribution of Sedna-like orbits sculpted by multiple stellar encounters is indicative of the birth cluster size. We also report our observed latitude distribution and implications for the size of the plutino population.
