Taxonomy of Centaurs and Trans-Neptunian Objects

The original publication is available at http://iopscience.iop.org/1538-3881/.International audienceTrans-Neptunian objects (TNOs) and Centaurs display thewidest color diversity in comparison to other small solar system bodies. The investigation of their properties can help in understanding the evolution of these objects. In this paper we propose a classification scheme based on multivariate statistical analysis of a homogeneous, high-quality set of B - V, V - R, V - I , and V - J color indices. Analyzing a sample of 51 objects and using a high confidence level, four groups have been identified and named: BB, BR, IR, and RR. The group BB contains objects with neutral color and RR those with very red color, while the others have intermediate behavior. We extend the analysis to 84 other objects for which three colors are available, obtaining a preliminary classification. A tentative interpretation of these groups in terms of surface characteristics is given

Near-IR spectroscopy of asteroids 21 Lutetia, 89 Julia, 140 Siwa, 2181 Fogelin, and 5480 (1989YK8), potential targets for the Rosetta mission; remote observations campaign on IRTF

In the frame of the international campaign to observe potential target asteroids for the Rosetta mission, remote observations have been carried out between Observatoire de Paris, in Meudon-France, and the NASA Infrared Telescope Facility on Mauna Kea. The SpeX instrument was used in the 0.8-2.5 microns spectral region, for two observing runs in March and June 2003. This paper presents near-IR spectra of the asteroids 21 Lutetia, 89 Julia, 140 Siwa, 2181 Fogelin, and 5480 (1989YK8). Near-IR spectra of the asteroids 21 Lutetia and 140 Siwa are flat and featureless. The spectrum of 89 Julia reveals absorption bands around 1 and 2 microns, which may indicate the presence of olivine and olivine-pyroxene mixtures and confirm the S-type designation. The small main-belt asteroids 2181 Fogelin and 5480 (1989YK8) are investigated spectroscopically for the first time. Near-IR spectra of these asteroids also show an absorption feature around 1 micron, which could be and indicator of igneous/metamorphic surface of the objects; new observations in visible as well as thermal albedo data are necessary to draw a reliable conclusion on the surface mineralogy of both asteroids.Comment: Sent: October 2003, Accepted: December, 200

Asteroid observations at low phase angles. IV : Average parameters for the new H, G1, G2 magnitude system

Peer reviewe

REASONS OF STUDENT SOCIAL APATHY

The purpose of the article: The purpose of this study is to identify the social representations of students about the manifestations of social apathy and its causes. The leading methods for the study of this problem are the method of questioning, which allows conducting a qualitative analysis of students’ social representations about the manifestations of social apathy and its causes; to identify the opinion of students about the manifestations of social apathy in the behavior of young people. Materials and methods: As the main method of research in this work, the method of questioning is chosen. Results of the research: Positions of overcoming of social apathy are allocated: social apathy is a personal problem with which the person has to cope independently, nobody can help him with it; the help of collective in the solution of this problem is necessary; participation of professional psychologists is necessary. The point of view of students is revealed that the solution to this problem has to be complex: the person, collective, psychologists, other social institutions. A number of features of social behavior attributed to people subject to social apathy are shown: unsociability, isolation, irresponsibility, passivity, immersion in their own problems, exposure to someone else's influence, and an understated level of claims. Applications: This research can be used for universities, teachers, and students. Novelty/Originality: In this research, the model of reasons for student social apathy is presented in a comprehensive and complete manner

Asteroid target selection for the new Rosetta mission baseline: 21 Lutetia and 2867 Steins

Reproduced with permission. Copyright ESO. Article published by EDP Sciences and available at http://www.aanda.org.International audienceThe new Rosetta mission baseline to the comet 67P/Churyumov-Gerasimenko includes two asteroid fly-bys. To help in target selection we studied all the candidates of all the possible scenarios. Observations have been carried out at ESO-NTT (La Silla, Chile), TNG (Canaries), and NASA-IRTF (Hawaii) telescopes, in order to determine the taxonomy of all the candidates. The asteroid targets were chosen after the spacecraft interplanetary orbit insertion manoeuvre, when the available total amount of ΔV was known. On the basis of our analysis and the available of ΔV, we recommended to the ESA ScienceWorking Group the asteroids 21 Lutetia and 2867 Steins as targets for the Rosetta mission. The nature of Lutetia is still controversial. Lutetia's spectral properties may be consistent with a composition similar to carbonaceous chondrite meteorites. The spectral properties of Steins suggest a more extensive thermal history. Steins may have a composition similar to relatively rare enstatite chondrite/achondrite meteorites

Kharkiv database of asteroid absolute magnitudes : Comparative analysis with other datasets

We present a database of the absolute magnitudes of asteroids named the Kharkiv Asteroid Absolute Magnitude Database (KhAAMD). The database includes a homogeneous set of the absolute magnitudes for about 400 asteroids in the new HG(1)G(2) magnitude system. We performed a comparative analysis of the asteroid absolute magnitudes between the Kharkiv database and other main magnitude databases (MPC, Pan-STARRS, ATLAS, PTF, and Gaia). We show that the Pan-STARRS absolute magnitude dataset has no systematic deviations and is the most suitable for the determination of diameters and albedos of asteroids. For the MPC dataset, there is a linear trend of overestimating the absolute magnitudes of bright objects and underestimating the magnitudes of faint asteroids. The ATLAS dataset has both a systematic overestimation of asteroid magnitudes and a linear trend. We propose equations that can be used to correct for systematic errors in the MPC and the ATLAS magnitude datasets. There are possible systematic deviations of about 0.1 mag for the Gaia and PTF databases but there are insufficient data overlapping with our data for a definitive analysis.Peer reviewe

Division III: Commission 15: Physical Studies of Comets and Minor Planets

The business meeting of IAU Commission 15 (C15) took place in Beijing on 29 August 2012, from 14:00 to 18:00, in room 405 of the China National Convention Center. This report of the business meeting of Commission 15 at the 2012 IAU GA is based on the report provided by Alberto Cellino, past president, and on the minutes taken by Daniel Hestroffer, secretary of Commission 15 in the triennium 2009 to 2012, and current secretary. <P /

Photometry of the Didymos System across the DART Impact Apparition

On 2022 September 26, the Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the satellite of binary near-Earth asteroid (65803) Didymos. This demonstrated the efficacy of a kinetic impactor for planetary defense by changing the orbital period of Dimorphos by 33 minutes. Measuring the period change relied heavily on a coordinated campaign of lightcurve photometry designed to detect mutual events (occultations and eclipses) as a direct probe of the satellite’s orbital period. A total of 28 telescopes contributed 224 individual lightcurves during the impact apparition from 2022 July to 2023 February. We focus here on decomposable lightcurves, i.e., those from which mutual events could be extracted. We describe our process of lightcurve decomposition and use that to release the full data set for future analysis. We leverage these data to place constraints on the postimpact evolution of ejecta. The measured depths of mutual events relative to models showed that the ejecta became optically thin within the first ∼1 day after impact and then faded with a decay time of about 25 days. The bulk magnitude of the system showed that ejecta no longer contributed measurable brightness enhancement after about 20 days postimpact. This bulk photometric behavior was not well represented by an HG photometric model. An HG 1 G 2 model did fit the data well across a wide range of phase angles. Lastly, we note the presence of an ejecta tail through at least 2023 March. Its persistence implied ongoing escape of ejecta from the system many months after DART impact