Articulos(CASLEO)
http://hdl.handle.net/11336/11
Articulos de COMPLEJO ASTRONOMICO "EL LEONCITO"Wed, 21 Nov 2018 03:24:20 GMT2018-11-21T03:24:20ZMicrovariability in AGNs: study of different statistical methods. I. Observational Analysis
http://hdl.handle.net/11336/64567
Microvariability in AGNs: study of different statistical methods. I. Observational Analysis
Zibecchi, Lorena Cecilia; Andruchow, Ileana; Cellone, Sergio Aldo; Carpintero, Daniel Diego; Romero, Gustavo Esteban; Combi, Jorge Ariel
We present the results of a study of different statistical methods currently used in the literature to analyse the (micro)variability of active galactic nuclei (AGNs) from ground-based optical observations. In particular, we focus on the comparison between the results obtained by applying the so-called C and F statistics, which are based on the ratio of standard deviations and variances, respectively. The motivation for this is that the implementation of these methods leads to different and contradictory results, making the variability classification of the light curves of a certain source dependent on the statistics implemented.<br />For this purpose, we re-analyse the results on an AGN sample observed along several sessions with the 2.15-m ?Jorge Sahade? telescope (CASLEO), San Juan, Argentina. For each AGN we constructed the nightly differential light curves. We thus obtained a total of 78 light curves for 39 AGNs, and we then applied the statistical tests mentioned above, in order to re-classify the variability state of these light curves and in an attempt to find the suitable statistical methodology to study photometric (micro)variations. We conclude that, although the C criterion is not proper a statistical test, it could still be a suitable parameter to detect variability and that its application allows to get more reliable variability results, in contrast with the F test.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/11336/645672017-01-01T00:00:00ZCratering rate on Pluto produced by the inner trans-Neptunian population
http://hdl.handle.net/11336/63630
Cratering rate on Pluto produced by the inner trans-Neptunian population
Calandra, Maria Florencia; Gil Hutton, Ricardo Alfredo
Aims. The aim of this work is to obtain the cratering rate on Pluto and to estimate the size distribution of the population in the inner trans-Neptunian region. Methods. We find the intrinsic collisional probability and the mean collision velocity for the interaction between Pluto and the projectile population crossing its orbit, using the L7 Synthetic Model from the CFEPS Project. The size distribution of this population is found using the smallest satellite of Pluto, Styx, as a constraint, because it survives the collisional process for the solar system age. Results. We find that the mean intrinsic collisional probability and mean collision velocity between Pluto and the projectile population are (Pi) = 1.3098 × 10-22 km-2 yr-1 and (Vcol) = 2.005 ± 0.822 km s-1. If the projectile sample is separated between Plutinos and non-Plutinos and the intrinsic collisional probability of these sub-populations are taken into account, we find a ratio of approximately 20:1 in favor of non-Plutinos resulting in the greatest contribution to the cratering rate on Pluto. The projectile population for the inner trans-Neptunian belt is characterized using a double power-law mean-size distribution with exponents qA = 3.5 and qB = 5.14 for the small and large size end of the population, respectively, and break radius at rb = 11.86 km or 7.25 km for mean densities of the projectiles ρ1 = 1.85 g cm-3 and ρ2 = 1 g cm-3. With this mean-size distribution we find that an object with radius of ~28 km produces a crater in Pluto with a diameter of ~250 km in a time larger than the solar system age, indicating that this kind of large structure has a very low probability of occurrence.
Mon, 01 May 2017 00:00:00 GMThttp://hdl.handle.net/11336/636302017-05-01T00:00:00ZCollision avoidance method for multi-operator multi-robot teleoperation system
http://hdl.handle.net/11336/63626
Collision avoidance method for multi-operator multi-robot teleoperation system
García, Sebastián Ernesto; Slawiñski, Emanuel; Mut, Vicente Antonio; Penizzotto Bacha, Franco Victor
SUMMARY This paper proposes a collision avoidance method for the teleoperation of multiple non-holonomic mobile robots from multiple users. Each human operator drives a mobile robot, where each one performs an independent task in a common workspace. To avoid collisions, the proposed method only acts on the speed of the mobile robots; therefore, the human operator can freely drive the robot over the path he chooses to. The developed analysis allows us to assure that a solution is always achieved. Finally, the results of the experiments are shown, in order to test the performance of the proposed control scheme.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/11336/636262018-01-01T00:00:00ZRefining the asteroid taxonomy by polarimetric observations
http://hdl.handle.net/11336/63617
Refining the asteroid taxonomy by polarimetric observations
Belskaya, I. N.; Fornasier, S.; Tozzi, G. P.; Gil Hutton, Ricardo Alfredo; Cellino, A.; Antonyuk, K.; Krugly, Yu. N.; Dovgopol, A. N.; Faggi, S.
We present new results of polarimetric observations of 15 main belt asteroids of different composition. By merging new and published data we determined polarimetric parameters characterizing individual asteroids and mean values of the same parameters characterizing different taxonomic classes. The majority of asteroids show polarimetric phase curves close to the average curve of the corresponding class. We show that using polarimetric data it is possible to refine asteroid taxonomy and derive a polarimetric classification for 283 main belt asteroids. Polarimetric observations of asteroid (21) Lutetia are found to exhibit possible variations of the position angle of the polarization plane over the surface.
Wed, 01 Mar 2017 00:00:00 GMThttp://hdl.handle.net/11336/636172017-03-01T00:00:00Z