Search

We present here a dynamical and observational study of the comet C/2017 U7 (PANSTARRS). This comet was discovered in 2017 and found to have a hyperbolic orbit. Our dynamical analysis shows that the object has probably originated in the Oort cloud, however an interstellar origin cannot be discarded. The observations were obtained in 2018 and 2019 using the Goodman High Throughput Spectrograph (GHTS) at the SOAR telescope. We obtained visible spectra covering the wavelength range of and also images in the SDSS filters system. Both the low-resolution reflectance spectrum and the reflectance spectra derived from the SDSS filters show an atypical band at . We conducted a comparative study of the colors and reflectance spectra of different small body populations (e.g., comets, Centaurs, and trans-Neptunian objects or TNOs) from the literature and concluded that the spectra and the colors of this comet are atypical, showing only some overlap with those of some known members of the TNOs and Centaurs, within the large uncertainties of the measurements of those populations. It is found that the feature and overall spectral shape can be reproduced by laboratory spectra of kerite, a template for aliphatic-rich hydrocarbons that has been previously identified in NIR cometary spectra absorptions. It is tentatively proposed that the unusual spectral shape is the result of a particle size distribution of dust grains in the coma or on the surface that has arisen due to a low grain ejection velocity from the surface and large nucleus size., Unidad Deptal. de Astronomía y Geodesia, Fac. de Ciencias Matemáticas, FALSE, pub

Context. Recent results for asteroid rotation periods from the TESS mission showed how strongly previous studies have underestimated the number of slow rotators, revealing the importance of studying those targets. For most slowly rotating asteroids (those with P > 12 h), no spin and shape model is available because of observation selection effects. This hampers determination of their thermal parameters and accurate sizes. Also, it is still unclear whether signatures of different surface material properties can be seen in thermal inertia determined from mid-infrared thermal flux fitting. Aims. We continue our campaign in minimising selection effects among main belt asteroids. Our targets are slow rotators with low light-curve amplitudes. Our goal is to provide their scaled spin and shape models together with thermal inertia, albedo, and surface roughness to complete the statistics. Methods. Rich multi-apparition datasets of dense light curves are supplemented with data from Kepler and TESS spacecrafts. In addition to data in the visible range, we also use thermal data from infrared space observatories (mainly IRAS, Akari and WISE) in a combined optimisation process using the Convex Inversion Thermophysical Model. This novel method has so far been applied to only a few targets, and therefore in this work we further validate the method itself. Results. We present the models of 16 slow rotators, including two updated models. All provide good fits to both thermal and visible data.The obtained sizes are on average accurate at the 5% precision level, with diameters found to be in the range from 25 to 145 km. The rotation periods of our targets range from 11 to 59 h, and the thermal inertia covers a wide range of values, from 2 to <400 J m−2 s−1∕2 K−1, not showing any correlation with the period. Conclusions. With this work we increase the sample of slow rotators with reliable spin and shape models and known thermal inertia by 40%. The thermal inertia values of our sample d

Context. Recent results for asteroid rotation periods from the TESS mission showed how strongly previous studies have underestimated the number of slow rotators, revealing the importance of studying those targets. For most slowly rotating asteroids (those with P > 12 h), no spin and shape model is available because of observation selection effects. This hampers determination of their thermal parameters and accurate sizes. Also, it is still unclear whether signatures of different surface material properties can be seen in thermal inertia determined from mid-infrared thermal flux fitting. Aims. We continue our campaign in minimising selection effects among main belt asteroids. Our targets are slow rotators with low light-curve amplitudes. Our goal is to provide their scaled spin and shape models together with thermal inertia, albedo, and surface roughness to complete the statistics. Methods. Rich multi-apparition datasets of dense light curves are supplemented with data from Kepler and TESS spacecrafts. In addition to data in the visible range, we also use thermal data from infrared space observatories (mainly IRAS, Akari and WISE) in a combined optimisation process using the Convex Inversion Thermophysical Model. This novel method has so far been applied to only a few targets, and therefore in this work we further validate the method itself. Results. We present the models of 16 slow rotators, including two updated models. All provide good fits to both thermal and visible data.The obtained sizes are on average accurate at the 5% precision level, with diameters found to be in the range from 25 to 145 km. The rotation periods of our targets range from 11 to 59 h, and the thermal inertia covers a wide range of values, from 2 to <400 J m−2 s−1∕2 K−1, not showing any correlation with the period. Conclusions. With this wor

Context. Recent results for asteroid rotation periods from the TESS mission showed how strongly previous studies have underestimated the number of slow rotators, revealing the importance of studying those targets. For most slowly rotating asteroids (those with P > 12 h), no spin and shape model is available because of observation selection effects. This hampers determination of their thermal parameters and accurate sizes. Also, it is still unclear whether signatures of different surface material properties can be seen in thermal inertia determined from mid-infrared thermal flux fitting. Aims. We continue our campaign in minimising selection effects among main belt asteroids. Our targets are slow rotators with low light-curve amplitudes. Our goal is to provide their scaled spin and shape models together with thermal inertia, albedo, and surface roughness to complete the statistics. Methods. Rich multi-apparition datasets of dense light curves are supplemented with data from Kepler and TESS spacecrafts. In addition to data in the visible range, we also use thermal data from infrared space observatories (mainly IRAS, Akari and WISE) in a combined optimisation process using the Convex Inversion Thermophysical Model. This novel method has so far been applied to only a few targets, and therefore in this work we further validate the method itself. Results. We present the models of 16 slow rotators, including two updated models. All provide good fits to both thermal and visible data.The obtained sizes are on average accurate at the 5% precision level, with diameters found to be in the range from 25 to 145 km. The rotation periods of our targets range from 11 to 59 h, and the thermal inertia covers a wide range of values, from 2 to <400 J m−2 s−1∕2 K−1, not showing any correlation with the period. Conclusions. With this wor