ﻻ يوجد ملخص باللغة العربية
On 28th January 2018, the large Trans-Neptunian Object (TNO) 2002TC302 occulted a m$_v= $15.3 star with ID 130957813463146112 in the Gaia DR2 stellar catalog. 12 positive occultation chords were obtained from Italy, France, Slovenia and Switzerland. Also, 4 negative detections were obtained near the north and south limbs. This represents the best observed stellar occultation by a TNO other than Pluto, in terms of the number of chords published thus far. From the 12 chords, an accurate elliptical fit to the instantaneous projection of the body, compatible with the near misses, can be obtained. The resulting ellipse has major and minor axes of 543 $pm$ 18 km and 460 $pm$ 11 km, respectively, with a position angle of 3 $pm$ 1 degrees for the minor axis. This information, combined with rotational light curves obtained with the 1.5m telescope at Sierra Nevada Observatory and the 1.23m telescope at Calar Alto observatory, allows us to derive possible 3D shapes and density estimations for the body, based on hydrostatic equilibrium assumptions. The effective area equivalent diameter is $sim$ 84 km smaller than the radiometrically derived diameter using thermal data from Herschel and Spitzer Space Telescopes. This might indicate the existence of an unresolved satellite of up to $sim$ 300 km in diameter, to account for all the thermal flux, although the occultation and thermal diameters are compatible within their error bars given the considerable uncertainty of the thermal results. The existence of a potential satellite also appears to be consistent with other ground-based data presented here. From the effective occultation diameter combined with H$_V$ measurements we derive a geometric albedo of 0.147 $pm$ 0.005, which would be somewhat smaller if 2002TC302 has a satellite. The best occultation light curves do not show any signs of ring features or any signatures of a global atmosphere.
We present results from the first recorded stellar occultation by the large trans-Neptunian object (174567) Varda that was observed on September 10$^{rm th}$, 2018. Varda belongs to the high-inclination dynamically excited population, and has a satel
Transneptunian objects (TNOs) are a source of invaluable information to access the history and evolution of the outer solar system. However, observing these faint objects is a difficult task. As a consequence, important properties such as size and al
Trans-Neptunian objects (TNOs) and Centaurs are remnants of our planetary system formation, and their physical properties have invaluable information for evolutionary theories. Stellar occultation is a ground-based method for studying these small bod
A stellar occultation by the extreme large-perihelion trans-Neptunian object (541132) Lele={a}k={u}honua (also known by the provisional designation of 2015 TG387) was predicted by the Lucky Star project and observed with the Research and Education Co
We present results from three world-wide campaigns that resulted in the detections of two single-chord and one multi-chord stellar occultations by the Plutino object (84922) 2003~VS$_2$. From the single-chord occultations in 2013 and 2014 we obtained