Animação e rock'n'roll usados para facilitar ensino de astronomia e química

Por sua característica multidisciplinar, a astronomia tem sido amplamente utilizada na aplicação da pesquisa científica no ensino de ciências naturais. As chamadas por projetos de ensino e divulgação científica, visando a produção de materiais didáticos, configuram-se em excelentes oportunidade de aliar o fascínio da população pelos astros e a informação que estes podem trazer sobre conceitos básicos das ciências fundamentais. No presente trabalho descrevemos a experiência em criar materiais didáticos em linguagem atrativa aos jovens (livros de história em quadrinhos; filmes de animação) com o objetivo de ampliar a cultura cientifica entre o público em geral. Para os estudantes da graduação, nossos projetos fazem parte das açoes afirmativas que buscam diminuir a evasão e estimular a conclusão no tempo ideal. Esse artigo é dedicado à descrição da metodologia adotada e apresentação de alguns exemplos dos resultados alcançados, nesse tipo de atuação “antes” e “depois” do ingresso do estudante na graduação.Due to its multidisciplinary character, astronomy has been subject of educational projects that use scientific research to improve the learning of natural sciences. The financial support in the form of Announcements of Opportunities, devoted to the production of teaching and outreach material, are the best way to combine the fascination that people have about the stars, with the information that these objects can bring concerning the basic concepts related to fundamental sciences. In the present work, we describe the experience in developing educational resources by adopting modern communication language (comics, animations) that is attractive among young people. Our goal is to enlarge the scientific culture of the citizens. For undergraduate students, our projects aim to diminish the evasion, as well as to promote the course conclusion in the ideal period. The paper is dedicated to describe the adopted methodology and to report the partial results of acting “before “and “after” the student entrance in the undergraduate course

X-ray sources associated with young stellar objects in the star forming region CMaR1

In previous Works we studied the star forma on scenario in the molecular cloud\ud Canis\ud Major\ud R1\ud (CMa\ud R1),\ud derived\ud from\ud the\ud existence\ud of\ud young\ud stellar\ud popula<on\ud groups\ud near\ud the\ud Be\ud stars\ud Z\ud CMa\ud and\ud GU\ud CMa,\ud using\ud data\ud from\ud the\ud ROSAT\ud X-­‐ray\ud satellite.\ud In\ud order\ud to\ud inves<gate\ud the\ud nature\ud of\ud these\ud objects\ud and\ud to\ud test\ud a\ud possible\ud scenario\ud of\ud sequen<al\ud star\ud forma<on\ud in\ud this\ud region,\ud four\ud fields\ud (each\ud 30\ud arcmin\ud diameter,\ud with\ud some\ud overlap\ud –\ud Fig.\ud 1)\ud have\ud been\ud observed\ud with\ud the\ud XMM-­‐Newton\ud satellite,\ud with\ud a\ud sensi<vity\ud about\ud 10\ud <mes\ud be_er\ud than\ud ROSAT.\ud The\ud XMM-­‐Newton\ud data\ud are\ud currently\ud under\ud analysis.\ud Preliminary\ud results\ud indicate\ud the\ud presence\ud of\ud about\ud 324\ud sources,\ud most\ud of\ud them\ud apparently\ud having\ud one\ud or\ud more\ud near-­‐infrared\ud counterparts\ud showing\ud typical\ud colors\ud of\ud young\ud stars.\ud The\ud youth\ud of\ud the\ud X-­‐ray\ud sources\ud was\ud also\ud confirmed\ud by\ud X-­‐ray\ud hardness\ud ra<o\ud diagrams\ud (XHRD),\ud in\ud different\ud energy\ud bands,\ud giving\ud an\ud es<mate\ud of\ud their\ud LX/Lbol\ud ra<os.\ud In\ud addi<on\ud to\ud these\ud results,\ud we\ud present\ud a\ud detailed\ud study\ud of\ud the\ud XMM\ud field\ud covering\ud the\ud cluster\ud near\ud Z\ud CMa.\ud Several\ud of\ud these\ud sources\ud were\ud classified\ud as\ud T\ud Tauri\ud and\ud Herbig\ud Ae/Be\ud stars,\ud using\ud op<cal\ud spectroscopy\ud obtained\ud with\ud Gemini\ud telescopes,\ud in\ud order\ud to\ud validate\ud the\ud use\ud of\ud XHRD\ud applied\ud to\ud the\ud en<re\ud sample.\ud This\ud classifica<on\ud is\ud also\ud used\ud to\ud confirm\ud the\ud rela<on\ud between\ud the\ud luminosi<es\ud in\ud the\ud near-­‐infrared\ud and\ud X-­‐ray\ud bands\ud expected\ud for\ud the\ud T\ud Tauri\ud stars\ud in\ud CMa\ud R1.\ud In\ud the\ud present\ud work\ud we\ud show\ud the\ud results\ud of\ud the\ud study\ud based\ud on\ud the\ud spectra\ud of\ud about\ud 90\ud sources\ud found\ud nearby\ud Z\ud CMa.\ud We\ud checked\ud that\ud the\ud X-­‐ray\ud spectra\ud (0.3\ud to\ud 10\ud keV)\ud of\ud young\ud objects\ud is\ud different\ud from\ud that\ud observed\ud in\ud field\ud stars\ud and\ud extragalac<c\ud objects.\ud Some\ud of\ud the\ud candidates\ud also\ud have\ud light\ud curve\ud showing\ud flares\ud that\ud are\ud typical\ud of\ud T\ud Tauri\ud stars,\ud which\ud confirms\ud the\ud young\ud nature\ud of\ud these\ud X-­‐ray\ud sources.CNP

A X-ray view of the young star population in CMA R1

In previous works we studied the star formation scenario in the molecular cloud Canis Major R1 (CMa R1), revealing the existence of young stellar groups near the Be stars Z CMa and GU CMa. Using data from the ROSAT X-ray satellite, Gregorio-Hetem et al. (2009) - GH2009 - discovered in this region young stellar objects (YSOSs) mainly grouped in two clusters of different ages. In order to investigate the nature of these objects and to test a possible scenario of sequential star formation in this region, four fields (each 30' diameter, with some overlap - (Fig. 1) have been observed with the XMM-Newton satellite that has a sensitivity about 10 times better than ROSAT.Resumo publicado no periódico: Revista Mexicana de Astronomía y Astrofísica. Serie de Conferencias, v. 44, p. 32, 2014

The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets Around Debris Disk Stars

We have completed a high-contrast direct imaging survey for giant planets around 57 debris disk stars as part of the Gemini NICI Planet-Finding Campaign. We achieved median H-band contrasts of 12.4 mag at 0.5" and 14.1 mag at 1" separation. Follow-up observations of the 66 candidates with projected separation < 500 AU show that all of them are background objects. To establish statistical constraints on the underlying giant planet population based on our imaging data, we have developed a new Bayesian formalism that incorporates (1) non-detections, (2) single-epoch candidates, (3) astrometric and (4) photometric information, and (5) the possibility of multiple planets per star to constrain the planet population. Our formalism allows us to include in our analysis the previously known Beta Pictoris and the HR 8799 planets. Our results show at 95% confidence that 5MJup planet beyond 80 AU, and 3MJup planet outside of 40 AU, based on hot-start evolutionary models. We model the population of directly-imaged planets as d^2N/dMda ~ m^alpha a^beta, where m is planet mass and a is orbital semi-major axis (with a maximum value of amax). We find that beta 1.7. Likewise, we find that beta < -0.8 and/or amax < 200 AU. If we ignore the Beta Pic and HR 8799 planets (should they belong to a rare and distinct group), we find that 3MJup planet beyond 10 AU, and beta < -0.8 and/or alpha < -1.5. Our Bayesian constraints are not strong enough to reveal any dependence of the planet frequency on stellar host mass. Studies of transition disks have suggested that about 20% of stars are undergoing planet formation; our non-detections at large separations show that planets with orbital separation > 40 AU and planet masses > 3 MJup do not carve the central holes in these disks.Comment: Accepted to ApJ on June 24, 2013. 67 pages, 17 figures, 12 table

Determinação de parâmetros estelares

Por meio da análise dos dados, neste projeto o estudante desenvolve habilidades de trabalhar com técnicas de tratamento de imagens astronômicas e de interpretação dos resultados. O trabalho envolve o aprendizado de princípios básicos a respeito da estrutura e da evolução estelar que pode ser adaptado para o desenvolvimento de atividades práticas voltadas para disciplinas do Bacharelado em Astronomia do IAG, no âmbito do programa “Ensinar com Pesquisa”.\ud Inicialmente foi realizado um estudo dirigido a respeito dos conceitos básicos sobre a determinação de parâmetros estelares. Para conhecer as técnicas e ferramentas de tratamento de imagens, foram realizados experimentos envolvendo técnicas fotométricas e determinação do brilho e cores das estrelas. Na segunda parte do trabalho os dados observacionais disponíveis foram analisados para construir curvas de luz de estrelas variáveis e determinar sua distância.\ud O período de pulsação foi determinado com base na variação do brilho em função do tempo. A partir da relação período-luminosidade é possível estimar a magnitude absoluta e calcular a diferença para a magnitude aparente, a qual depende da distância do objeto. Obtém-se assim o módulo de distância da estrel

On the association of young star: clusters and their parental clouds: a statistical fractal analysis

We present a study of 21 young star clusters aiming to characterize their association to dense cllouds. The structure of the clouds was evaluated by means of the Q statistical fractal analysis, designed to compare their geometric structure with the spatial distribution of the cluster memebers. The sample was selected from the study by Santos-Silva and Gregorio-Hetem (2012, A&A, 547, A107) that evalueted the radial density profile of the stellar superficial distribution of the young clusters. The fractal dimension and other statistical parameters of most of the sample indicate that there is a good cloud-cluster correlation, whem compared to other works based on an artificial distribution of point (Lomax et al. 2011, MNRAS, 412, 627). As presented in a previous work (Fernandes et al. 2012, A&A, 541, A95), the cluster NGC 6530 is the only object of our sample that presents anomalous statistical behaviour. The fractal analysis shows that this cluster has a centrally concentrated distribution of stars that differs from the substructures found in the density distribution of the cloud projected in the Av map, suggesting that the original cloud geometry was changed by the cluster formation.Resumo publicado no periódico: Revista Mexicana de Astronomía y Astrofísica. serie de Conferencias, v. 44, p. 140, 2014

The nature of X-ray sources associated to young clusters around SH2-296

Aiming to unravel the star formation activity in\ud the Canis Major R1 (CMaR1), we have studied the\ud young (< 5 Myr) clusters associated to the arcshaped\ud ionized nebula Sh2-296. Based on our Xray\ud data complemented by optical and near-IR data,\ud we discovered, near to GU CMa, a stellar cluster\ud that is older by at least a few Myr than the previously\ud known cluster, around Z CMa, where star\ud formation is still very active. Multi-object optical\ud spectroscopy of our X-ray sources nearby Z CMa was\ud performed with Gemini telescopes to confirm the existence\ud of a mixed population from both older and\ud younger clusters around the edge of Sh2-296. In the\ud present work we show the results for optical counterparts\ud candidates of 45 X-ray sources. Spectral type\ud determination was based on comparison with standard\ud spectra library and fitting the continuum and\ud TiO bands. Typical features of young stars were inspected\ud to confirm the nature of the sample that is\ud mainly classified as T Tauri stars (TTs), since their\ud spectra show the Li I line, one of the indicators of\ud youth. The equivalent width of Hα measured at 10%\ud of the total flux was used to separate Classical TTs\ud (CTTs) from weak-line TTs (WTTs). Among 51\ud optical counterparts candidates, 38 are young stars:\ud 24% of them are classified as CTTs and 76% are\ud WTTs. However the present results correspond to\ud a small fraction (∼15%) of the entire sample of Xray\ud sources we have detected. Aiming a more representative\ud set of spectra, additional GMOS observations\ud have been performed, as well as another ongoing\ud project (see Santos-Silva et al.) dedicated to\ud studying of the X-ray properties.Resumo publicado no periódico:\ud Revista Mexicana de Astronomía y Astrofísica. Serie de Conferencias, v. 44, p.139, 201