Recent Talks

List of all the talks in the archive, sorted by date.


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Tuesday February 14, 2023
Dr. Nicolas Martin
Observatoire Astronomique de Strasbourg

Abstract

Dwarf galaxies are powerful tools of near-field cosmology and galactic archaeology: their numbers, distribution, and star formation can be linked to both the tenets of LCDM (the missing satellite "problem," their (an)isotropic distribution, their dark matter content) and to the build up of their hosts and their environment (accretion, quenching). The exquisite detail offered by observation of the nearby Milky Way dwarf galaxies has built a picture of what dwarf galaxies are and how they evolved through time. In this talk, I will review the increasingly sharp view we are building of the dwarf-galaxy system of the Milky Way's "sister" galaxy, Andromeda, and emphasize key similarities and differences between these two systems of satellites in the hope to learn what features are common or, on the contrary, driven by the different pasts of the Milky Way and Andromeda.


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Tuesday February 7, 2023
Mattew Maniscalco
TNO

Abstract

TNO is big non-profit Dutch company with more than 3000 professionals. In this talk an introduction about TNO and its capabilities applied to astronomy will be presented. TNO has done the preliminary design of the Adaptive Secondary Mirror for the European Solar Telescope. TNO also develops other optical devices for ground based and space astronomy and also for optical communications.

 

Youtube: https://youtube.com/live/_b6Tdzr_Cq0?feature=share


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Tuesday January 31, 2023
Dr. Paolo Molaro
INAF-Osservatorio Astronomico di Trieste

Abstract

Lithium is a key   element which plays an important role in  astronomy  as well as everyday human life.  Nevertheless it is probably the only element whose astronomical origin is still a mystery.  A fraction of  about 30% of what is measured today was  made in the first 3 minutes of the Universe and about 10% is  made  by spallation  reactions of  cosmic rays with the atoms in the interstellar medium. However, as stars burn  Li in their hot interiors and what makes the remaining ~60%  is still unknown.  The recent detections of   7Li and 7Be in the outburst of   classical novae is a landmark in the solution of this long standing mystery. The discovery   confirms a theoretical speculation  made about 50 years ago    but  which was never  supported by observations.   Since then  the  presence of Be-7 has been confirmed to be ubiquitous in about a dozen classical novae and very recently also in the  recurrent nova RS Oph that blew out in August 2021.  However, the observed values show  tension with theory  being one order of magnitude greater than predictions.  Detailed Li Galactic chemical evolution models   assuming the "observed" yields  show that indeed  Novae could  be the long sought  source for the Galactic  7Li. 


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Friday January 27, 2023
Prof. Belén Gavela
IFT/UAM

Abstract

 

 After introducing the concepts of axions and axion-like-particles (ALPs) and their signals, true axions which can be either much heavier or much
lighter than the canonical axion will be discussed. The implications for dark matter, neutron stars and gravitational waves searches will  also be addressed.

 

 


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Thursday January 26, 2023
Prof. M. Person
MIT

Abstract

After three intense and fruitful weeks, the first MIT student camp at the OT is coming to an end. We celebrate the achievements of this successful pilot experience of collaboration between the two institutions with a special event where the students will present their results with the following talks:

  • Oris Neto - HD370222 and its spectral melodies (PI: Dr. Sergio Simon-Diaz, IAC)
  • Claire McLellan-Cassivi - Determining rotation periods of 3 Koronis family asteroids (PI: Dr. Steven Slivan, MIT)
  • Mohan Richter-Addo - Astrometric calibration of the Artemis telescope (PI: Dr. Michael Person, MIT)
  • Helena McDonald - Observations of historic IAC dwarf stars in the modern epoch (PIs: Drs. Rafael Rebolo and Roi Alonso, IAC)
  • Hillary Andales - Host galaxies properties of mid-infrared tidal disruption event candidates (PI: Megan Masterson, MIT)
  • Kylee Carden - Followup observations of TESS objects of interest: Discovering (real) other worlds (PI: Dr. Michael Person, MIT)

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Thursday January 26, 2023
Dr. David Martínez Delgado
IAA-CSIC

Abstract

Within the hierarchical framework for galaxy formation, merging and
tidal interactions are expected to shape large galaxies up to the
present day. While major mergers are quite rare at present, minor
mergers and satellite disruptions - that result in stellar streams -
should be common, and are indeed seen in the stellar halos of the Milky
Way and the Andromeda galaxy. In the last years, the Stellar Stream
Legacy Survey (PI. Martinez-Delgado) has exploited available deep
imaging of some nearby spiral galaxies with the ultimate aim of
estimating the frequency, morphology and stellar luminosity/mass
distribution of these structures in the local Universe. In this talk, I
will present the first results of our systematic survey of stellar
streams together with some recent follow-up observations (e.g. Megara,
Subaru) and N-body modelling of the most striking streams. Finally,
I will discuss what we can learn about galaxy formation from the results
of this survey, including the comparison with the available L-CDM
cosmological simulations, and our plans to extend this stream survey
at lower surface brightness regime with the recently approved ARRAKHIS,
the first ESA fast-mission lead by Spain.





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Tuesday January 24, 2023
Anish Amarsi
Uppsala University

Abstract

Spectroscopic analyses of stellar chemical compositions are model-dependent, and shortcomings in the models often limit the accuracy of the final results.  For late-type stars like our Sun, two of the main problems in present-day methods are that they assume the stellar atmosphere is a) one-dimensional (1D) and hydrostatic, and b) satisfies local thermodynamic equilibrium (LTE).  We can relax these assumptions simultaneously by performing detailed 3D non-LTE radiative transfer post-processing of 3D radiative-hydrodynamic model stellar atmospheres.  I shall give a brief overview of this approach, and illustrate its impact on carbon, oxygen, and iron abundances in late-type stars.


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Thursday January 19, 2023
Prof. José Alberto Rubiño-Martín
IAC

Abstract

I will review the status of the QUIJOTE (Q-U-I JOint TEnerife) experiment, a project led from the IAC with the aim of characterising the polarisation of the Cosmic Microwave Background (CMB) and other galactic or extragalactic physical processes that emit in microwaves in the frequency range 10-42GHz, and at large angular scales (1 degree resolution). QUIJOTE consists of two telescopes and three instruments operating from the Teide Observatory, and started operations about 10 years ago, in November 2012.

I will discuss the status of the project, and I will present the latest scientific results associated with the wide survey carried out with the first QUIJOTE instrument (MFI) at 11, 13, 17 and 19GHz, covering approximately 29000 deg$^2$ with polarisation sensitivities in the range of 35-40 $\mu$K/deg. These MFI maps provide the most accurate description we have of the polarization of the emission of the Milky Way in the microwave range, in a frequency domain previously unexplored by other experiments. These maps provide a unique view of the Galactic
magnetic field as traced by the synchrotron emission. These results have been presented in an initial series of 6 scientific articles published on January 12th, 2023.

Finally, I will describe the prospects for future CMB observations from the Teide Observatory.


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Thursday January 12, 2023
Dr. Carlos del Burgo
National Institute of Astrophysics, Optics and Electronics (INAOE)

Abstract

The ESA's PLATO mission is mainly aimed at finding exoplanets similar to Earth, orbiting around sun-like stars. The characterization of the planets strongly depends on that of their host stars. A precise determination of some fundamental stellar parameters can be achieved from spectroscopic observations. High-resolution optical echelle spectra from HARPS and PEPSI were used to resemble observations at lower resolving powers R= 5000, 11 200, 20 000, and 65 000, for high and low signal to noise ratios, in order to establish the necessary strategy to properly characterize a sample of stars. The effective temperature, metallicity, microturbulence, and surface gravity were derived from different techniques based on either spectral synthesis or equivalent widths. This was performed by independent research teams belonging to the PLATO consortium. For the exercise, the teams worked on the same dataset without knowing the identity of the stars. The results obtained are compared to judge which techniques are the best in terms of accuracy for every resolving power. This talk summarizes the results of this blind competition. 


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Thursday December 15, 2022
Dr. Rui Marques-Chaves
Univ. Genève

Abstract

In this talk, I will present recent results on a new sample of extremely UV-luminous star-forming galaxies at z=2-4 discovered within the 9000deg^2-wide Baryon Oscillation Spectroscopic Survey database of the Sloan Digital Sky Survey. These puzzling sources show apparent magnitudes rivaling those of bright QSOs, but without any hint of AGN activity or being magnified by gravitational lensing. Instead, these sources are characterized by very young stellar populations (~ 10 Myr) and compact morphologies. The two highest-redshift sources in our sample show very high Lyman continuum (LyC, with >13.6 eV) escape fractions, up to fesc(LyC)~90%, being the most powerful ionizing sources identified so far among the star-forming galaxy population, both in terms of the intrinsic LyC photon production rate and escape. With SFRs~1000 Msun/yr, but almost un-obscured, and specific star formation sSFR >50-100 Gyr^-1, these sources are very efficient star-forming galaxies, possibly representing a short-lived phase in the evolution of massive and compact galaxies. I will highlight some unique properties observed in these sources including LyC emission, complex Lyman-alpha profiles, strong wind lines, SEDs, among others. Finally, I discuss the properties of these UV-bright sources in the broad context of galaxy formation and evolution, and possible implications to cosmic reionization.