Ciclo de Seminários 2021

Publicado em 09/04/2021 11h19 Atualizado em 11/05/2021 14h32

A Coordenação de Astronomia e Astrofísica (COAST) do Observatório Nacional organiza regularmente seminários e colóquios semanais de interesse da comunidade astronômica. Durante este ano os seminários acontecerão de forma remota (Zoom e Youtube) todas as quintas-feiras. Dependendo da localização do palestrante os seminários poderão acontecer em dois horários distintos, às 10:00 ou às 15:00 (horário de Brasília).

Para mais informações: seminarioscoast@on.br

Transmissão pelo canal do ON no YouTube: https://www.youtube.com/user/observatorionacional

Maio

13/05 - Opening a new window on galaxy cluster astrophysics with XRISM

Resumo: The XRISM X-ray observatory will launch in the next few years, further advancing a new era of X-ray astronomy begun by the short-lived Hitomi mission five years ago. XRISM will fly Resolve, an X-ray imaging spectrometer that will provide an unprecedented combination of high spectral resolution, large collecting area, and broad energy coverage, and it will enable new insights into many areas of astrophysics. In this talk, I will describe XRISM and its instruments, Resolve and the Xtend wide-field X-ray imager, and discuss the mission science goals and how they will be achieved. I will focus on several science goals related to clusters of galaxies. These include understanding the role of AGN feedback in shaping the dynamics and chemical composition near the cluster core, understanding the importance of non-thermal pressure support from gas motion in the cluster outskirts, and validating atomic emission models, for which XRISM will provide unique data currently unavailable by other means. I will conclude with a look toward the capabilities of future X-ray missions, including Athena and Lynx.

Palestrante: Eric D. Miller 

Instituição: MIT Kavli Institute for Astrophysics and Space Research

Hora (BRT): 10:00

Link do semináriohttps://www.youtube.com/watch?v=q0_Yx0cM4LE


20/05 - What causes the accelerated expansion of the Universe?

Abstract: The expansion of the Universe is in an accelerated phase. This acceleration was first established by observations of SuperNovae, and has since been confirmed through a range of independent observations. The physical cause of this acceleration is coined Dark Energy, and most observations indicate that Einstein's cosmological constant provides a very good fit. In that case, approximately 70% of the energy of the Universe presently consists of this cosmological constant. I will in this talk address the possibility that there may exist other possible causes of the observed acceleration. In particular, I will discuss a concrete model, inspired by the well-known Lorentz force in electromagnetism, where Dark Matter causes the acceleration.  With a fairly simple numerical simulation we find that the model appears consistent with all observations. In such a model, where Dark Matter properties cause the acceleration of the Universe, there is no need for a cosmological constant.

Palestrante: Steen Harle Hansen

Instituição: Niels Bohr Institute/University of Copenhagen, Dinamarca

Hora (BRT): 15:00

Link do seminário


27/05 

Palestrante: Vanessa Hill

Instituição: Observatoire de la Côte d'Azur, França

 


 

Abril

08/04 - WEAVE: The 8-in-1 Massive Spectroscopic Survey

Abstract: The WHT Extended Aperture Velocity Explorer (or WEAVE) is a wide-field massive spectroscopic survey set to being this year. Its 8 surveys extend from our local kiloparsec to the largest scales and the end of the reionisation epoch. I will briefly review this new facilities on La Palma, before going through these 3 galactic and 5 extragalactic surveys. I will focus in particular on the WEAVE-QSO survey, which aims to obtain around 400,000 Lyman-alpha forest (z>2.1) quasar spectra. This European team is working closely with Brazilian colleagues to identify these quasars with the J-PAS survey. WEAVE-QSO will probe the intergalactic medium (IGM) from the largest scales to circumgalactic regions. Highlights include measuring the expansion of the universe (using baryon acoustic oscillations), and studying gas priorities with both a map of the cosmic web and galaxy proximity information. 

Palestrante: Matthew Pieri

Instituição: Laboratoire d'Astrophysique de Marseille

Hora (BRT): 10:00

Link do semináriohttps://www.youtube.com/watch?v=iVOZIvGQyiA


15/04 - The Mars 2020 Mission – Following the Water as a Necessity for Life

Abstract: The Perseverance rover has successfully landed in Jezero crater on Mars on February 18, 2021 and started operations. In my talk, I will present an overview of the mission and rover, and how they fit into NASA’s grand strategy of Mars exploration. I will show the Mars 2020 mission’s goals and how Perseverance’s instruments will achieve them. In the second half of my talk, I will talk about my personal involvement in the mission, specifically with MEDA, the rover’s weather station. Water is one of the main necessities for life as we know it and MEDA has the capability to better our understanding of water exchange between Mars’ atmosphere and regolith. I will give an overview of different water exchange mechanisms and the role that salts in the Martian regolith can play in them. Finally, I will talk about our experimental work at the University of Michigan on the role of these salts in the Martian water cycle under present-day conditions.

Palestrante: Erik Fischer 

Instituição: Department of Climate and Space Sciences and Engineering, University of Michigan (EUA)

Hora (BRT): 15:00

Link do seminário: https://www.youtube.com/watch?v=WJSNAO1_5J0


22/04 - Heracles: uma galáxia anã no coração da Via Láctea

Resumo:  A Arqueologia Galáctica é uma área da astrofísica dedicada a desvendar a história de formação da nossa Galáxia, a Via Láctea, tendo como base observacional a cinemática e a composição química de suas populações estelares.  Este campo tem tido um avanço estupendo na última década com o lançamento do satélite astrométrico Gaia e do empreendimento de vários levantamentos de larga escala, que vêm obtendo espectros de alta qualidade para milhões de estrelas.  Dentre esses projetos destaca-se o APOGEE (Apache Point Observatory Galactic Evolution Experiment), do qual nosso grupo de Liverpool é parte integrante.  Nesta palestra vou descrever como empregamos os dados de APOGEE e Gaia, além de sofisticadas simulações numéricas cosmológicas, para revelar a presença dos restos de um satélite que colidiu com a Via Láctea nos estágios iniciais de sua vida.  Estimamos que a massa deste satélite é da ordem de 500 milhões de massas solares, configurando assim o evento de acresção mais importante da história de nossa Galáxia e perfazendo aproximadamente um terço do seu halo estelar.  Discutirei brevemente as implicações deste evento para nossa compreensão da história evolutiva da Via Láctea e como ela se compara às de outras galáxias do mesmo porte.

Palestrante: Ricardo Schiavon 

Instituição: Astrophysics Research Institute, at Liverpool John Moores University (Reino Unido)

Hora (BRT): 10:00

Link do semináriohttps://www.youtube.com/watch?v=6VRhSQFP7wQ


29/04 - Cosmic Discordances

Palestrante: Alessandro Melchiorri 

Instituição: La Sapienza & INFN, Rome (Itália)

Hora (BRT): 15:00

Link do semináriohttps://www.youtube.com/watch?v=QxS1o5OlYQI