http://localhost:8080/tede/handle/tede/8 2026-06-02T19:47:01Z http://localhost:8080/tede/handle/tede/221 “ANÁLISE PRELIMINAR DA CLASSIFICAÇÃO TAXONÔMICA DE PEQUENOS CORPOS DO SISTEMA SOLAR A PARTIR DE DADOS DA CAMPANHA FOTOMÉTRICA J-PLUS” Cilio Marques Santos, Cilio Marques Santos Jorge Marcio Ferreira Carvano , Jorge Marcio Ferreira Carvano We classified 170 asteroids based on reflectances obtained in the J-PLUS photometric campaign. The data used were corrected using a genetic algorithm that aimed to correct noise due to rotation. We used Principal Component Analysis and K-MEANS cluster analysis as classification methods. Our classification resulted in twelve groups, with five spectrally close to class S, with a band at 1.0 microns associated with the possible presence of silicates; three to class C, with no absorption characteristics; two to classes V and Q with a very pronounced band to the right of 0.77 microns; one to class K or L; and one to class Ch, with a pronounced band at 0.7 microns, associated with hydration. Since the definition of nomenclature was based on visual inspection comparing the Bus classes, we chose to define a scheme that indicates the two most likely classes. In terms of the heliocentric distribution, we did not find results that differ from previous works Observatorio Nacional Dissertação 2025-09-05T00:00:00Z http://localhost:8080/tede/handle/tede/213 “O ELO PERDIDO NA EVOLUÇÃO DE RÁDIO-GALÁXIAS: INVESTIGANDO EMISSÕES ESTENDIDAS EM BAIXA FREQUÊNCIA” Vinícius Sanches Moreira Lima, Vinícius Sanches Moreira Lima Alberto Rodríguez Ardila , Alberto Rodríguez Ardila Active galactic nuclei (AGNs) with jets are morphologically classified according to their evolutionary stage, with Gigahertz Peaked-Spectrum (GPS) and Compact SteepSpectrum (CSS) sources traditionally understood as representing the young and confined phase of jets. However, the paradigm of a linear evolution has been challenged by an abundance of compact sources and the discovery of objects featuring a young nucleus embedded within a structure related to extended and aged emission, indicating multiple episodes of activity (“restarted” jets). This work aims to re-evaluate a sample of 84 sources previously classified as GPS/CSS by leveraging the unparalleled sensitivity of the LOFAR Two-metre Sky Survey (LoTSS) at 144 MHz to detect extended, low-surface-brightness emission undetectable in surveys above 1 GHz. We combined multi-frequency data (from 144 MHz to 4.85 GHz) to perform a comparative morphological analysis and construct Spectral Energy Distributions (SEDs). Our results show that 9 sources (17.3%) display clear morphological evidence of extended emission, being classified as restarted. Another 9 sources (17.3%) are classified as restarted jet candidates, and 28 (53.8%) remain compact. Spectral analysis reveals a diversity of classes (GPS, CSS, HFP, and spectra without peaks or flattened at low frequencies), with a tendency for restarted sources to have steeper (CSS-like) spectra. We conclude that a significant fraction of compact sources are, in fact, restarted jets, suggesting that jet activity is a cyclic and intermittent process. This result has profound implications for evolutionary models of radio galaxies and for the understanding of feedback exerted by multiple episodes of activity Observatorio Nacional Dissertação 2025-10-08T00:00:00Z http://localhost:8080/tede/handle/tede/212 “EVALUATION OF THE DYNAMICAL STATE OF THE HIGHREDSHIFT GALAXY CLUSTER SPT-CL J2215-3537” VINICIUS DOS SANTOS BESSA RIBEIRO, VINICIUS DOS SANTOS BESSA RIBEIRO Renato de Alencar Dupke, Renato de Alencar Dupke The accurate determination of the dynamical state of galaxy clusters is critical for cluster cosmology, as near-equilibrium processes in the intracluster medium of dynami- cally relaxed systems enable the derivation of the mass distribution and other important scaling relations with minimal uncertainties. Recently the galaxy cluster SPT-CL J2215- 3537 (z = 1.16) has been identified as one of the most distant relaxed cluster using the symmetry–peakiness–alignment (SPA) criterion, which consists in the construction of X-ray morphological statistics to assess the degree of relaxation. However, SPT-CLJ0615- 5746 (z = 0.97), which was previously marked as relaxed by the SPA treatment, showed signs to be in a merging state when analyzed by the intracluster light fraction and tradi- tional X-ray analysis. The present work aims to evaluate the dynamical state of SPT-CL J2215-3537 through X-ray spectral and imaging analyzes. The characterization of the thermodynamical properties of the intracluster medium and its morphological features reveals signatures of sloshing cold fronts in the SE-NW axis. We find a ghost cavity candidate and estimate its mechanical power as log10{Pcav/(10^42 erg/s)} = 2.66+-0.23, indicanting that radiative cooling strongly exceeds AGN feedback heating. The results from our combined analysis suggest that SPT-CL J2215-3537 is mildly disturbed. We use the feedback-regulated precipitation framework to show that the cluster’s core is likely in a transient state towards a stable cooling-feedback cycle within the next ~ 100+-70 Myr. We additionally recalculate traditional X-ray morphological parameters and present a discussion of its limitations for high-redshift clusters. Observatorio Nacional Dissertação 2025-09-02T00:00:00Z http://localhost:8080/tede/handle/tede/211 “CARACTERIZANDO ESTRELAS GIGANTES VERMELHAS NO AGLOMERADO ABERTO IC 2714: UM ESTUDO ECTROSCÓPICO E ASTROMÉTRICO” Thiago Flaulhabe Xavier Gomes, Thiago Flaulhabe Xavier Gomes José Nacizo Holanda Junior, José Nacizo Holanda Junior In this work, our objective is to conduct a comprehensive study of a sample of eight red giants previously reported as members of the open cluster IC 2714. Using high-resolution spectra, we have performed a chemical analysis by determining atmospheric parameters, projected rotational velocities, and chemical abundances for 21 species in the sample, employing equivalent width measurements and spectral synthesis as techniques. Further- more, using robust algorithms from recent literature, we have conducted a membership study using astrometric data and estimated the physical parameters of the cluster through isochrone fitting. Our astrometric study allows us to classify 898 stars as cluster members, and due to their discrepant astrometric results, two stars in our sample were classified as non-members. The chemical abundances of all the red giants classified as members in our sample agree with literature results for dwarfs and giants in the solar neighbor- hood. Moreover, three stars in our sample exhibit anomalous rotation, and among them, we report a lithium-rich giant candidate. To explain this chemically peculiar nature, we suggest that this star underwent accretion of a planet or substellar companion, which possibly triggered a self-enrichment lithium process. Finally, we discuss our results for the open cluster IC 2714 in the context of chemical gradients in the Galaxy and the study of cosmic chronometers. The results of this work can contribute to the study of stellar nucleosynthesis models and Galactic chemical evolution models, in addition to guiding possible more in-depth studies. Observatorio Nacional Dissertação 2025-03-12T00:00:00Z