Past Pizza Lunches

Número de entradas: 144

17
Noviembre 2017

Finding the double sunsets: close binary stars and large spectroscopic surveys


Inicio: 12:00h
Ponente: Carles Badenes ((University of Pittsburgh/ICCUB))
Lugar: Alberto Lobo Conference Room S1-01

I will discuss our present knowledge of the statistics of stellar multiplicity (the multiplicity fraction and the distribution of periods, mass ratios, and eccentricities), and the implications for stellar evolution, in particular for Type Ia Supernovae (SN Ia). I will describe how multi-epoch radial…
Inicio: 12:00h
Ponente: Carles Badenes ((University of Pittsburgh/ICCUB))
Lugar: Alberto Lobo Conference Room S1-01

I will discuss our present knowledge of the statistics of stellar multiplicity (the multiplicity fraction and the distribution of periods, mass ratios, and eccentricities), and the implications for stellar evolution, in particular for Type Ia Supernovae (SN Ia). I will describe how multi-epoch radial velocity measurements from large spectroscopic surveys can open a new observational window on stellar multiplicity, and present two case studies: white dwarfs in SDSS/SEGUE, and red giants in SDSS/APOGEE. For the white dwarfs, we can measure their merger rate and evaluate their viability as Type Ia SN progenitors. For the red giants, we can explore the interplay between stellar evolution and stellar multiplicity, evaluate the rate of stellar mergers, and uncover a strong dependence of the multiplicity fraction with metallicity.
10
Noviembre 2017

Growing black holes: from the first seeds to active galactic nuclei


Inicio: 12:15h
Ponente: Mar Mezcua Pallerola (ICE)
Lugar: Sala Alberto Lobo

How supermassive black holes form and grow is still one of the long-standing questions in astronomy. Supermassive black holes of up to 10^10 solar masses already existed when the Universe was less than ~1 Gyr old. To reach this mass in such a short time, they should have started as seed intermediate-mass…
Inicio: 12:15h
Ponente: Mar Mezcua Pallerola (ICE)
Lugar: Sala Alberto Lobo


How supermassive black holes form and grow is still one of the long-standing questions in astronomy. Supermassive black holes of up to 10^10 solar masses already existed when the Universe was less than ~1 Gyr old. To reach this mass in such a short time, they should have started as seed intermediate-mass black holes (IMBHs) of 100-10^6 solar masses and grow very fast via accretion and mergers. Such IMBHs are the missing link between stellar and supermassive black holes and they should be present in the nucleus of low-mass galaxies and in the halos of large galaxies, e.g. in the form of ultraluminous X-ray sources (ULXs). 
In this talk I will present observational evidence that a population of IMBHs in dwarf galaxies similar to those seed black holes populating the early Universe exists. With the use of large, deep, multiwavelength surveys like COSMOS, these sources are detected up to z~4. I will also show that, in the local Universe, IMBHs can be additionally detected as extreme ULXs with powerful radio emission in galaxies having undergone a minor merger event. The later supermassive black hole growth can be explained by the accretion of gas coming from galactic scales. At kpc scales, this gas can be transported to the nuclear regions through galaxy mergers, which can trigger active galactic nuclei (AGN) activity and can be detected in the form of binary AGN. At scales of a few 100 pc, dust lanes can be the channels of inflow of material from the outer parts of the galaxy to the nuclear region, as evidenced by the finding that the spiral structure of the nuclear cold molecular gas traced by ALMA observations correlates with that of the dust. The nuclear dust lanes are in addition able to obscure the nucleus of low-luminosity AGN and to explain the collimation of the ionised gas, which questions the role of the dusty torus proposed by the Unified Model of AGN. 
03
Noviembre 2017

Collapse & Explosion of electron degenerate stellar cores


Inicio: 12:15h
Ponente: Jordi Isern Vilaboy
Lugar: Sala Alberto Lobo

Electron degenerate stellar cores are potentially unstable as a consequence of the independence of the pressure with the temperature and, if electrons are relativistic, on the softness of the equation of state. Depending on the initial conditions and chemical composition of these cores, the outcome of…
Inicio: 12:15h
Ponente: Jordi Isern Vilaboy
Lugar: Sala Alberto Lobo

Electron degenerate stellar cores are potentially unstable as a consequence of the independence of the pressure with the temperature and, if electrons are relativistic, on the softness of the equation of state. Depending on the initial conditions and chemical composition of these cores, the outcome of the instability can be a supernova explosion and/or the formation of a neutron star or a black hole. In this talk we concentrate on the fate of carbon-oxygen and oxygen-neon cores.
27
Octubre 2017

GNSS Transpolar Earth Reflectometry exploriNg system (G-TERN): a proposal for ESA EE9 co-led by ICE-CSIC/IEEC


Inicio: 12:15h
Ponente: Estel Cardellach Galí
Lugar: Sala Alberto Lobo

The GNSS Transpolar Earth Reflectometry exploriNg system (G-TERN) was proposed in response to ESA’s Earth Explorer 9 Revised Call by a team of 33 multi-disciplinary scientists and co-led by E. Cardellach (ICE-CSIC/IEEC) and J. Wickert (GFZ/Germany). The primary objective of the mission is to quantify…
Inicio: 12:15h
Ponente: Estel Cardellach Galí
Lugar: Sala Alberto Lobo

The GNSS Transpolar Earth Reflectometry exploriNg system (G-TERN) was proposed in response to ESA’s Earth
Explorer 9 Revised Call by a team of 33 multi-disciplinary scientists and co-led by E. Cardellach (ICE-CSIC/IEEC) and J. Wickert (GFZ/Germany). The primary objective of the mission is to quantify crucial characteristics, processes and interactions between the sea ice and other Earth system components in order to advance the understanding and prediction of climate change and its impacts on the environment and society.  To contribute answering these questions G-TERN will measure key parameters of the sea ice, the oceans and the atmosphere with frequent and dense coverage over polar areas, becoming a ’dynamic mapper’ of the ice conditions, ice production and loss in multiple time and space scales, and surrounding environment. Over polar areas, G-TERN will measure sea ice surface elevation (<10 cm precision), roughness and
polarimetry aspects at 30 km resolution and 3 days full coverage. G-TERN will implement the interferometric GNSS reflectometry concept (pioneered at ICE-CSIC/IEEC).  The lifetime would be 2025-2030 or optimally 2025-2035, covering key stages of the transition towards a Summer Arctic sea ice free. ESA will take a decision by the end of 2017 and proceed with Phase-A studies of two selected proposals. This seminar will provide an overview of G-TERN mission goals, techniques and suggested implementation.
20
Octubre 2017

The flux of chondritic meteorites reaching the Earth over time and its astro-biological implications


Inicio: 12:30h
Ponente: Josep M. Trigo-Rodríguez (ICE)
Lugar: Sala L3 / 01 (workshop room third floor)

A recent study led by ICE has revealed the unique catalytic properties of the minerals forming chondritic meteorites, authentic primordial aggregates of the materials forming the protoplanetary disk. These minerals are able to catalyze tens of organics compounds that are considered essential in prebiotic…
Inicio: 12:30h
Ponente: Josep M. Trigo-Rodríguez (ICE)
Lugar: Sala L3 / 01 (workshop room third floor)

A recent study led by ICE has revealed the unique catalytic properties of the minerals forming chondritic meteorites, authentic
primordial aggregates of the materials forming the protoplanetary disk. These minerals are able to catalyze tens of organics compounds that are
considered essential in prebiotic chemistry. These meteorites come from highly porous transitional asteroids that retained significant amounts of
water,  organics  and volatile compounds in their interiors. Our scenario suggests that these bodies caused an intense meteoritic flux that
delivered about 5 to 6 orders of magnitude the current one (estimated to be 10^5 metric tons).
It traduces in huge amounts of chondritic materials reaching  the Earth’s surface at an annual rate of thousands of billions of metric tons, and
exposed to the action of water, nitrogen species and igneous heat. Under these unique properties of chondrites, and such primordial circumstances
we envision that they probably played a key role in fertilizing the Earth’s surface towards the appearance of life in Earth about 4 Gyrs ago.
23
Junio 2017

Magnetars: recent discoveries and a catalogue of their outbursts


Inicio: 12:00h
Ponente: Francesco Coti Zelati (ICE)
Lugar: Sala Alberto Lobo

I will present recent X-ray observational results on two peculiar strongly magnetized isolated neutron stars: SGR 1745-2900, the closest pulsar to a black hole ever observed; 1E 161348–505, the slowest magnetar known at the centre of a supernova remnant. I will also show the results of a systematic…
Inicio: 12:00h
Ponente: Francesco Coti Zelati (ICE)
Lugar: Sala Alberto Lobo

I will present recent X-ray observational results on two peculiar strongly magnetized isolated neutron stars: SGR 1745-2900, the
closest pulsar to a black hole ever observed; 1E 161348–505, the slowest magnetar known at the centre of a supernova remnant. I will also show the results of a systematic study of all magnetar outbursts detected in the past 2 decades.
16
Junio 2017

Anatomy of the archetypal protostellar shock L1157-B1


Inicio: 12:00h
Ponente: Gemma Busquet (Institut de Ciències de l'Espai (IEEC-CSIC))
Lugar: Sala Alberto Lobo, ICE

During the earliest protostellar stages of their formation, young stars generate fast collimated winds (or jets) which impact the parent molecular cloud through shock fronts.  Protostellar shocks play a crucial role in the chemical evolution of star-forming clouds because they induce in the surrounding…
Inicio: 12:00h
Ponente: Gemma Busquet (Institut de Ciències de l'Espai (IEEC-CSIC))
Lugar: Sala Alberto Lobo, ICE

During the earliest protostellar stages of their formation, young stars generate fast collimated winds (or jets) which impact the parent molecular cloud through shock fronts. 
Protostellar shocks play a crucial role in the chemical evolution of star-forming clouds because they induce in the surrounding medium large variation of temperature and density, which can locally activate endothermic gas-phase reactions, ionization processes, and evaporation/erosion of dust grains and their icy mantles. The nature and properties of these shocks and jets are a source of major debate. The launching mechanism of the jet, the role of the magnetic field, or the shock properties (i.e. ionization fraction) are some of the key questions that remain to be answered
Associated with a low-mass Class 0 protostar, L1157-B1 is a protostellar chemically rich bow-shock that has been extensively studied from the infrared to millimeter wavelengths.
In this talk I’ll review the most relevant aspects of protostellar shocks and for the particular case of the shock laboratory L1157-B1. I’ll also present the recent work we are conducting with several telescopes to obtain a comprehensive view of the bow-shock structure and shock chemistry. 
09
Junio 2017

Obtaining precipitation information from Polarimetric GNSS radio occultation observables


Inicio: 12:00h
Ponente: Ramon Padullés Rulló (Institute of Space Sciences)
Lugar: Sala de Conferencias Alberto Lobo

The Earth observation satellite PAZ will be finally launched by the end of this year, thanks to the agreement signed between Hisdesat (the owner of the satellite) and SpaceX. PAZ will test the new Polarimetric Radio Occultation observation concept. During the last years, the theoretical framework of…
Inicio: 12:00h
Ponente: Ramon Padullés Rulló (Institute of Space Sciences)
Lugar: Sala de Conferencias Alberto Lobo

The Earth observation satellite PAZ will be finally launched by the end of this year, thanks to the agreement signed between Hisdesat (the owner of the satellite) and SpaceX. PAZ will test the new Polarimetric Radio Occultation observation concept. During the last years, the theoretical framework of the concept has been set, the feasibility of the technique has been proven and some applications have been investigated. In this talk I will briefly review the most relevant aspects of the technique, and I will focus on the characterization of the signal, describing the effects that electromagnetic waves emitted from the GPS undergo in their way to the receiver. A detailed set of simulations has been performed in order to test the performance of the retrieval algorithms, that allow us to obtain precipitation information from the differential phase measurements.  
02
Junio 2017

Challenges in Gravitational Wave Astronomy


Inicio: 12:00h
Ponente: Carlos Sopuerta (ICE (CSIC-IEEC))
Lugar: Sala Alberto Lobo (ICE)

In this talk I will summarize the efforts to detect gravitational waves in the different frequency bands, describing what are the main challenges, not only from the point of view of instrumentation, but also from the point of view of data analysis and science exploitation.  This talk will be complementary…
Inicio: 12:00h
Ponente: Carlos Sopuerta (ICE (CSIC-IEEC))
Lugar: Sala Alberto Lobo (ICE)

In this talk I will summarize the efforts to detect gravitational waves in the different frequency bands, describing what are the main challenges, not only from the point of view of instrumentation, but also from the point of view of data analysis and science exploitation.  This talk will be complementary to the one given recently about LISA in a recent pizza seminar, and in this sense, only material not introduced there will appear.
26
Mayo 2017

Supernova or impostor?


Inicio: 12:00h
Ponente: Nancy Elias-Rosa
Lugar: Sala Alberto Lobo

A fully consistent picture of the SNe progenitor evolution can't be found yet. Such scenario increases in complexity as deep and wide surveys, using latest generation instruments, discover new types of transients with unprecedented observational characteristics, for example, the wide heterogeneity…
Inicio: 12:00h
Ponente: Nancy Elias-Rosa
Lugar: Sala Alberto Lobo

A fully consistent picture of the SNe progenitor evolution can't be found yet. Such scenario increases in complexity as deep and wide surveys, using latest generation instruments, discover new types of transients with unprecedented observational characteristics, for example, the wide heterogeneity observed in interacting transients in the recent years. Still, the nature of these transients is largerly debated: Some are without doubt genuine core-collapse SNe, while others may be giant non-terminal outburst from luminous blue variables. The talk includes my contribution to this topic with data of the recent objects of study and the conclusions extracted from their analysis.
Institute of Space Sciences (IEEC-CSIC)

Campus UAB, Carrer de Can Magrans, s/n
08193 Barcelona.
Phone: +34 93 737 9788
Email: ice@ice.csic.es
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An institute of the Consejo Superior de Investigaciones Científicas

An institute of the Consejo Superior de Investigaciones Científicas
Affiliated with the Institut d'Estudis Espacials de Catalunya

Affiliated with the Institut d'Estudis Espacials de Catalunya