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101. Main belt asteroid shape distrib. from Gaia DR2
ID:
ivo://CDS.VizieR/J/AJ/156/139
Title:
Main belt asteroid shape distrib. from Gaia DR2
Short Name:
J/AJ/156/139
Date:
21 Oct 2021
Publisher:
CDS
Description:
Gaia Data Release 2 (Cat. I/345) includes observational data for 14099 pre-selected asteroids. From the sparsely sampled G-band photometry, we derive lower-limit light curve amplitudes for 11665 main belt asteroids (MBA) in order to provide constraints on the distribution of shapes in the asteroid main belt. Assuming a triaxial shape model for each asteroid, defined through the axial aspect ratios a>b and b=c, we find an average b/a=0.80+/-0.04 for the ensemble, which is in agreement with previous results. By combining the Gaia data with asteroid properties from the literature, we investigate possible correlations of the aspect ratio with size, semimajor axis, geometric albedo, and intrinsic color. Based on our model simulations, we find that MBAs greater than 50 km in diameter on average have higher b/a aspect ratios (are rounder) than smaller asteroids. We furthermore find significant differences in the shape distribution of MBAs as a function of the other properties that do not affect the average aspect ratios. We conclude that a more detailed investigation of shape distribution correlations requires a larger data sample than is provided in Gaia Data Release 2.
102. Main Belt asteroids observed by Spitzer
ID:
ivo://CDS.VizieR/J/A+A/578/A42
Title:
Main Belt asteroids observed by Spitzer
Short Name:
J/A+A/578/A42
Date:
21 Oct 2021
Publisher:
CDS
Description:
Multi-epoch Spitzer Space Telescope 24um data is utilized from the MIPSGAL and Taurus Legacy surveys to detect asteroids based on their relative motion. Infrared detections are matched to known asteroids and average diameters and albedos are derived using the Near Earth Asteroid Model (NEATM) for 1865 asteroids ranging in size from 0.2 to 169km. A small subsample of these objects was also detected by IRAS or MSX and the single wavelength albedo and diameter fits derived from these data are within the uncertainties of the IRAS and/or MSX derived albedos and diameters and available occultation diameters, which demonstrates the robustness of our technique. The mean geometric albedo of the small Main Belt asteroids in this sample is p_V_=0.134 with a sample standard deviation of 0.106. The albedo distribution of this sample is far more diverse than the IRAS or MSX samples. The cumulative size-frequency distribution of asteroids in the Main Belt at small diameters is directly derived and a 3{sigma} deviation from the fitted size-frequency distribution slope is found near 8km. Completeness limits of the optical and infrared surveys are discussed.
103. Main-belt asteroids optical light curves
ID:
ivo://CDS.VizieR/J/A+A/596/A40
Title:
Main-belt asteroids optical light curves
Short Name:
J/A+A/596/A40
Date:
21 Oct 2021
Publisher:
CDS
Description:
Because the second reaction wheel failed, a new mission was conceived for the otherwise healthy Kepler space telescope. In the course of the K2 mission, the telescope is staring at the plane of the Ecliptic. Thousands of solar system bodies therefore cross the K2 fields and usually cause additional noise in the highly accurate photometric data. We here follow the principle that some person's noise is another person's signal and investigate the possibility of deriving continuous asteroid light curves. This is the first such endeavor. In general, we are interested in the photometric precision that the K2 mission can deliver on moving solar system bodies. In particular, we investigate space photometric optical light curves of main-belt asteroids. We studied the K2 superstamps that cover the fields of M35, and Neptune together with Nereid, which were observed in the long-cadence mode (29.4min sampling). Asteroid light curves were generated by applying elongated apertures. We used the Lomb-Scargle method to determine periodicities that are due to rotation.
104. Main-belt asteroids polarimetric survey. II.
ID:
ivo://CDS.VizieR/J/A+A/539/A115
Title:
Main-belt asteroids polarimetric survey. II.
Short Name:
J/A+A/539/A115
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of a polarimetric survey of main-belt asteroids at Complejo Astronomico el Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. The data were obtained with the Torino and CASPROF polarimeters at the 2.15m telescope. The Torino polarimeter is an instrument that allows simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation.
105. Main-belt asteroids polarimetry. III
ID:
ivo://CDS.VizieR/J/A+A/542/A11
Title:
Main-belt asteroids polarimetry. III
Short Name:
J/A+A/542/A11
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of a polarimetric survey of main-belt asteroids at Complejo Astronomico El Leoncito (Casleo), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties.
106. Main-belt asteroids polarimetry. IV
ID:
ivo://CDS.VizieR/J/A+A/569/A122
Title:
Main-belt asteroids polarimetry. IV
Short Name:
J/A+A/569/A122
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of a polarimetric survey of main-belt asteroids at Complejo Astronomico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. The data were obtained using the Torino and CASPROF polarimeters at the 2.15m telescope. The Torino polarimeter is an instrument that allows simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation.
107. Main-belt asteroids polarimetry. VI.
ID:
ivo://CDS.VizieR/J/A+A/607/A103
Title:
Main-belt asteroids polarimetry. VI.
Short Name:
J/A+A/607/A103
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a polarimetric survey of main-belt asteroids at Complejo Astronomico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry and to estimate the diversity in the polarimetric properties of asteroids that belong to different taxonomic classes. The data were obtained using the CASPOL polarimeter at the 2.15 m telescope. CASPOL is a polarimeter based on a CCD detector and a Savart plate. The survey began in 1995 and data on a large sample of asteroids were obtained until 2012. A second period began in 2013 using a polarimeter with a more sensitive detector in order to study small asteroids, families, and special taxonomic groups. We present and analyze the unpublished results for 128 asteroids of different taxonomic types, 55 of them observed for the first time. The observational data allowed us to find probable new cases of Barbarian objects but also two D-type objects, (565) Marbachia and (1481) Tubingia, that seem to have phase-polarization curves with a large inversion angle. The data obtained combined with data from the literature enabled us to find phase-polarization curves for 121 objects of different taxonomic types and to study the relations between several polarimetric and physical parameters. Using an approximation for the phase-polarization curve we found the index of refraction of the surface material and the scatter separation distance for all the objects with known polarimetric parameters. We also found that the inversion angle is a function of the index of refraction of the surface, while the phase angle where the minimum of polarization is produced provides information about the distance between scatter particles or, to some extent, the porosity of the surface.
108. Main Belt asteroids with WISE/NEOWISE. I.
ID:
ivo://CDS.VizieR/J/ApJ/741/68
Title:
Main Belt asteroids with WISE/NEOWISE. I.
Short Name:
J/ApJ/741/68
Date:
01 Feb 2022 07:05:56
Publisher:
CDS
Description:
We present initial results from the Wide-field Infrared Survey Explorer (WISE), a four-band all-sky thermal infrared survey that produces data well suited for measuring the physical properties of asteroids, and the NEOWISE enhancement to the WISE mission allowing for detailed study of solar system objects. Using a NEATM thermal model fitting routine, we compute diameters for over 100000 Main Belt asteroids (MBAs) from their IR thermal flux, with errors better than 10%. We then incorporate literature values of visible measurements (in the form of the H absolute magnitude) to determine albedos. Using these data we investigate the albedo and diameter distributions of the Main Belt. As observed previously, we find a change in the average albedo when comparing the inner, middle, and outer portions of the Main Belt. We also confirm that the albedo distribution of each region is strongly bimodal. We observe groupings of objects with similar albedos in regions of the Main Belt associated with dynamical breakup families. Asteroid families typically show a characteristic albedo for all members, but there are notable exceptions to this.
109. Makemake (136472) long-term photometry
ID:
ivo://CDS.VizieR/J/A+A/625/A46
Title:
Makemake (136472) long-term photometry
Short Name:
J/A+A/625/A46
Date:
21 Oct 2021
Publisher:
CDS
Description:
We aim to study the rotational properties of the dwarf planet Makemake. The photometric observations were carried out at different telescopes between 2006 and 2017. Most of the measurements were acquired in BVRI broad-band filters of a standard Johnson-Cousins photometric system. We found that Makemake rotates more slowly than was previously reported. A possible lightcurve asymmetry suggests a double-peaked period of P=22.8266+/-0.0001h. A small peak-to-peak lightcurve amplitude in R-filter A=0.032+/-0.005mag implies an almost spherical shape or near pole-on orientation. We also measured BVRI colours and the R-filter phase-angle slope and revised the absolute magnitudes. The absolute magnitude of Makemake remained unchanged since its discovery in 2005. No direct evidence of a newly discovered satellite was found in our photometric data, however we discuss the possible existence of another larger satellite.
110. Mars Express astrometric obs. of Martian moons
ID:
ivo://CDS.VizieR/J/A+A/614/A15
Title:
Mars Express astrometric obs. of Martian moons
Short Name:
J/A+A/614/A15
Date:
21 Oct 2021
Publisher:
CDS
Description:
Both Martian moons, Phobos and Deimos, have been observed during several imaging campaigns by the SRC on Mars Express. Several tens of images are obtained during mutual event observations - when the Martian moons are both observed or together with another solar system body. These observations provide new opportunities to determine the bodies' positions in their orbits. A method was sought to automate the observation of the positions of the imaged bodies. Within one image sequence a similarly accurate localization of the objects in all images should be possible. Shape models of Phobos and Deimos are applied to simulate the appearance of the bodies in the images. Matching the illuminated simulation against the observation provides a reliable determination of the bodies' location within the image. To enhance the matching confidence several corrections need to be applied to the simulation to closely reconstruct the observation. In total 884 relative positions between the different objects are provided.