- 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 We present and analyze the unpublished results for 128 asteroids of different taxonomic types, 55 of them observed for the first time.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.
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Search Results
- 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/154/76
- Title:
- Masses of 30 large subject asteroids
- Short Name:
- J/AJ/154/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The conventional least-squares asteroid mass determination algorithm allows us to solve for the mass of a large subject asteroid that is perturbing the trajectory of a smaller test asteroid. However, this algorithm is necessarily a first approximation, ignoring the possibility that the subject asteroid may itself be perturbed by the test asteroid, or that the encounter's precise geometry may be entangled with encounters involving other asteroids. After reviewing the conventional algorithm, we use it to calculate the masses of 30 main-belt asteroids. Compared to our previous results, we find new mass estimates for eight asteroids (11 Parthenope, 27 Euterpe, 51 Neimausa, 76 Freia, 121 Hermione, 324 Bamberga, 476 Hedwig, and 532 Herculina) and significantly more precise estimates for six others (2 Pallas, 3 Juno, 4 Vesta, 9 Metis, 16 Psyche, and 88 Thisbe). However, we also find that the conventional algorithm yields questionable results in several gravitationally coupled cases. To address such cases, we describe a new algorithm that allows the epoch state vectors of the subject asteroids to be included as solve-for parameters, allowing for the simultaneous solution of the masses and epoch state vectors of multiple subject and test asteroids. We then apply this algorithm to the same 30 main-belt asteroids and conclude that mass determinations resulting from current and future high-precision astrometric sources (such as Gaia) should conduct a thorough search for possible gravitational couplings and account for their effects.
- ID:
- ivo://CDS.VizieR/J/A+A/320/652
- Title:
- Mass of (11) Parthenope
- Short Name:
- J/A+A/320/652
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The asteroid observations made with the automatic meridian circle at Bordeaux observatory from 1985 to 1994, and which have recently become available, are presented. The residuals of these observations obtained using the orbital elements published in the ``Ephemerides of Minor Planets for 1996'' are analysed. An anomaly for the asteroid (17) Thetis was found, indicating a current close encounter between this asteroid and (4) Vesta. Such an encounter will allow very interesting determinations of the mass of Vesta to be made in the future. Lastly, our determination of the mass of (11) Parthenope is discussed, which was based on its perturbations on the orbit of Thetis. The result obtained, (2.58+/-0.10)x10^-12^M{sun}, appears significant.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A84
- Title:
- Meteor showers new parent bodies
- Short Name:
- J/A+A/622/A84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several new meteor showers are added to the International Astronomical Union (IAU) list of meteor showers every year. Given the multiplication of video meteor measurements new parent bodies are to be found in addition to new showers. Such an endeavor is usually performed by comparing orbital elements, using a high threshold single-linking Dsh-criterion. However, questions remain about the accuracy of the method and the veracity of the newly associated parent bodies. Our goal is to find the presence of new parent bodies in a statistical meaningful way. A search for parent bodies was performed among SonotaCo and EDMOND databases. The association of asteroids with meteors was based on different methods, discussed and compared below. In addition, a thorough statistical test was performed in order to investigate the possible random associations. A list of potential new parent bodies associated with at least 50 meteors is found. A statistical test was used to show whether the group of meteor orbits and the asteroid is a random coincidence or not. Out of 54 potential new parent bodies, only three new parent bodies are not excluded by the statistical test: 2014 BN14, 2015 TX24 and 2015 QT3, with a probability of chance occurrence of 37, 10 and 13%, respectively. This shows the need for rigorous method when searching for the existence of meteor showers and parent bodies. Ideally, such a test (or even better, tests) should be conducted in order to confirm (or not) the current IAU list of meteor showers. Similarly, all meteor orbit data in our databases should ideally be revisited using the latest methods providing a better estimate of the real uncertainty and accuracy of the derived orbits.
- ID:
- ivo://CDS.VizieR/J/A+A/295/206
- Title:
- Meteor stream activity. II.
- Short Name:
- J/A+A/295/206
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the past two centuries, alert amateur and professional meteor astronomers have documented 35 outbursts of 17 individual meteor streams well enough to allow the construction of a homogeneous set of activity curves. These curves add to similar profiles of the annual streams in a previous paper (Paper I, See Cat. <J/A+A/287/990>). The activity curves, expressed in terms of Zenith Hourly Rates (ZHR), have a shape that is usually well described by: ZHR=ZHR(max)10^(-B|{lambda}_{sun }_-{lambda_{sun}_(max)}|)^. The steepness of the slopes varies from an exponent of B=7 to B=220 per degree of solar longitude, with a typical value of B=30.
- ID:
- ivo://CDS.VizieR/J/ApJ/831/197
- Title:
- Mg-rich olivines with electron microscopy
- Short Name:
- J/ApJ/831/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Antarctica micrometeorites (~1200) and cosmic spherules (~5000) from deep sea sediments are studied using electron microscopy to identify Mg-rich olivine grains in order to determine the nature of the particle precursors. Mg-rich olivine (FeO<5wt%) in micrometeorites suffers insignificant chemical modification during its history and is a well-preserved phase. We examine 420 forsterite grains enclosed in 162 micrometeorites of different types-unmelted, scoriaceous, and porphyritic-in this study. Forsterites in micrometeorites of different types are crystallized during their formation in solar nebula; their closest analogues are chondrule components of CV-type chondrites or volatile rich CM chondrites. The forsteritic olivines are suggested to have originated from a cluster of closely related carbonaceous asteroids that have Mg-rich olivines in the narrow range of CaO (0.1-0.3wt%), Al_2_O_3_ (0.0-0.3wt%), MnO (0.0-0.3wt%), and Cr_2_O_3_ (0.1-0.7wt%). Numerical simulations carried out with the Chemical Ablation Model (CABMOD; Vondrak+ 2008ACP.....8.7015V) enable us to define the physical conditions of atmospheric entry that preserve the original compositions of the Mg-rich olivines in these particles. The chemical compositions of relict olivines affirm the role of heating at peak temperatures and the cooling rates of the micrometeorites. This modeling approach provides a foundation for understanding the ablation of the particles and the circumstances in which the relict grains tend to survive.
- ID:
- ivo://CDS.VizieR/J/AJ/152/163
- Title:
- Mission Accessible Near-Earth Objects Survey
- Short Name:
- J/AJ/152/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Mission Accessible Near-Earth Objects Survey aims to physically characterize sub-km near-Earth objects (NEOs). We report the first photometric results from the survey that began in 2013 August. Photometric observations were performed using 1-4m class telescopes around the world. We present rotational periods and light curve amplitudes for 86 sub-km NEOs, though in some cases only lower limits are provided. Our main goal is to obtain light curves for small NEOs (typically, sub-km objects) and estimate their rotational periods, light curve amplitudes, and shapes. These properties are used for a statistical study to constrain overall properties of the NEO population. A weak correlation seems to indicate that smaller objects are more spherical than larger ones. We also report seven NEOs that are fully characterized (light curve and visible spectra) as the most suitable candidates for a future human or robotic mission. Viable mission targets are objects fully characterized, with {Delta}v^NHATS^{<=}12km/s, and a rotational period P>1hr. Assuming a similar rate of object characterization as reported in this paper, approximately 1230 NEOs need to be characterized in order to find 100 viable mission targets.
