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setembro de 2019

Radiation Line-driven Winds in B Supergiants – Lydia Cidale (Universidade Nacional de La Plata)

25 de setembro: 12:30 - 13:30
Anfiteatro Antonio Cabral,

The theory of radiatively driven stellar winds has been successful in describing the wind properties (mass-loss and terminal velocity) of massive supergiants. Inclusion of rotation in the models brought a remarkable progress in the development of this theory. Three types of stationary wind regimes are currently known; the classical fast solution, the Omega--slow solution that arises for fast rotators, and the delta--slow solution that takes place in highly ionized winds. We discuss the properties of these hydrodynamical solutions and their…

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outubro de 2019

TBA – Carmela Lardo (Laboratoire d’ Astrophysique, Ecole Polytechnique Fédérale de Lausanne, Observatoire de Sauvern)

2 de outubro: 12:30 - 13:30
Anfiteatro Antonio Cabral,

Carving out the low surface brightness universe – Mohammad Akhlaghi (Instituto de Astrofísica de Canarias)

9 de outubro: 12:30 - 13:30
Anfiteatro Antonio Cabral,

Astronomical instrumentation has greatly advanced over the last 40 years: with digital detectors, space telescopes and +8m class ground-based telescopes for example. However, in the methods/software regime, the signal-based detection paradigm from the 1970s (for example from Petrosian or Kron, mostly used as implemented in SExtractor from the mid-1990s) is still the dominant method of extracting high-level catalogs from the low-level image pixels. In this talk, after reviewing the major systematic biases regarding astronomical object detection that is inherent to…

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Dynamical effects of an eccentric giant planet on outer small body reservoirs – Gonzalo C. de Elía (Universidade Nacional de La Plata)

16 de outubro: 12:30 - 13:30
Anfiteatro Antonio Cabral,

The last 25 years of investigations concerning planetary sciences have led to a real explosion of new discoveries in extra-solar planets. In fact, the number of confirmed planets discovered to date outside the solar system amounts to about 4000, which show a wide diversity of physical and dynamical properties. In particular, giant gaseous exoplanets exist on diverse orbits with small, moderate, and high eccentricities, which even reach values of up to 0.97. The dynamical structure of planetary systems that host…

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Two decades of eyes wide open – The Gemini Observatory (Ricardo Salinas, Gemini South – La Serena)

17 de outubro: 13:30 - 15:10
Sala O207,

2019 marks the 20th anniversary of the first light at Gemini North in Hawai'i, which was quickly followed the next year by Gemini South in Chile. Since then, the Geminis have been serving the astronomy communities of a large partnership, including Brazil. In this talk I will review the pros and cons of the telescopes design; and its current and future instrumentation, with an emphasis on some new capabilities at Gemini South as speckle interferometry and high resolution spectroscopy. I…

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TBA – Ricardo Salinas (Gemini-South)

23 de outubro: 12:30 - 13:30
Anfiteatro Antonio Cabral,

Gauging Feedback from AGN at L[O III] > 10^42 erg/s – Bruno Dall’Agnol de Oliveira (UFRGS)

30 de outubro: 12:30 - 13:30

I will present the results of our work with a sample of 9 luminous (L >10^42 erg/s) type 2 QSOs, with redshifts 0.1 < z < 0.5. We used Hubble Space Telescope (HST) narrow-band images, centered on λ5007 and Hα+ emission lines, with the purpose of constraining the geometry of their extended narrow-line regions (ENLRs). The narrow-band images showed elongated ENLRs and bipolar ionization cones in /(Hα+) excitation maps, indicating that the torus still survives at…

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novembro de 2019

Remote sensing the atmospheres of giant exoplanets and brown dwarfs – Ben Burningham (University of Hertfordshire)

6 de novembro: 12:30 - 13:30

Studying the atmospheric compositions of directly imaged exoplanets and brown dwarfs presents a number of challenges, chief of which is the presence of thick clouds. Clouds introduce a variety of obstacles from both theoretical and observational perspectives. I will review different approaches to studying the atmospheres of cloudy brown dwarfs and giant exoplanets, and delve into some of my recent research unpicking the information encoded in their emission spectra.

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Cosmic murder mistery: what killed that galaxy? – Thiago Gonçalves (Observatório do Valongo/UFRJ)

13 de novembro: 12:30 - 13:30
Anfiteatro Antonio Cabral,

Galaxies are clearly divided into two main categories. One group shows ongoing star formation and blue colors, while the other contains mostly old stellar populations and red colors. The relative absence of objects with intermediate properties indicates that this transition must happen rapidly, and there should be an active mechanism to shut down star formation in many cases. In this talk I will give an overview of the observational projects our group has been conducting, emphasizing the need for deep…

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Sondando a Estrutura em Larga Escala com Supernovas – Miguel Quartin (UFRJ)

20 de novembro: 12:30 - 13:30
Anfiteatro Antonio Cabral,

As supernovas (SN) carregam informação valiosas sobre o espectro de potência da matéria atual e sua taxa de crescimento. Os efeitos de lente de SN introduzem não-gaussianidades, enquanto as velocidades peculiares das SN introduzem correlações. Mostrarei os vículos atuais combinando ambos métodos e previsões para o LSST. Discutirei como as diferentes propriedades do levantamento afetam as previsões de velocidades peculiares e mostrarei que há informação em uma faixa maior de redshift do que se pensava. Terminarei destacando o desafio computacional…

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