Radiation Line-driven Winds in B Supergiants
Lydia Cidale, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Argentina
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 applications in the context of B
emission-line stars.
Mass transport in galaxies
Joaquín Prieto, Departamento de Astronomía, Universidad de Chile, Argentina
Mass transport in galaxies is a key process to feed SMBHs. In this talk I will
show how both mass and angular momentum is redistributed in isolated first
galaxies and in merger of galaxies. Such phenomena finally result in BH
fuelling and active galactic nuclei.
On the impact flux and crater record of terrestrial planets and asteroids
Fernando Roig, Observatório Nacional, Río de Janeiro, Brasil
The crater record on different worlds provides important clues about the
evolution of the solar system. In particular, it may pose tight constraints to
the surface ages and to the dynamics of the impactors source. Here, I present
a brief introduction to the main approaches that are applied to address the
production of craters on terrestrial worlds and asteroids. Then, I show our
results from a recently developed self consistent model of the dynamical
evolution of the asteroid belt, which provides the probability of asteroidal
impacts, as a function of time, on the different worlds. Combining these
results with an appropriate scaling law, which gives the relationship between
the size of the impactor and the size of the produced crater, we obtain the
size frequency distribution of craters that can be compared to the
observations. Among other things, our results indicate that the flux of
asteroidal impacts on the terrestrial planets is totally different from that
on the asteroids themselves. While the Earth has received less than one impact of asteroids larger than 10 km (in diameter) during the last 1 Gyr, the
asteroids Ceres and Vesta recorded a significant number of such impacts.
Therefore, the lack of large craters on the surface of Ceres implies that this
body must be suffering an active process of surface rejuvenation. Our results
also put constraints to the primordial dynamical evolution of the planets,
indicating that the instability of the giant planets during the phase of
planetary migration occurred early in the history of the solar system.
Infrared Dust Bubbles: gas, dust and star formation
Cristina Cappa, Instituto Argentino de Radioastronomía, Argentina
A visual examination of the images at 8.0 $\mu$m from the GLIMPSE survey allowed the identification of about 600 full or partial IR dust bubbles (IRDB) in the inner Galactic plane, showing the presence of PAHs in photodissociation regions. Presently, more than 5000 IRDB have been identified in our Galaxy using different surveys at 8 $\mu$m. These bubbles are about 1-3 arcmin in size and show filamentary appearence. In this presentation I summarize the distribution of the ionized and molecular gas, and that of the dust at different temperatures linked to the bubbles using both radio and infrared data at different wavelengths. The origin of the bubbles and their relation to massive stars/embedded clusters are also analyzed. IRDB are present in dense media showing signs of recent star formation and their study is important for understanding triggered star formation scenarios. These bubbles provide a good insight of the sculpting influences of the winds and UV photons of massive stars on the molecular clouds where they are born.
Optical microvariability in Active Galactic Nuclei: truth, post-truth, and statistics
Sergio Cellone, Complejo Astronómico El Leoncito (CASLEO, CONICET – UNLP – UNC – UNSJ) & Facultad de Ciencias Astronómicas y Geofísicas (FCAG, UNLP)
It is a fact that Active Galactic Nuclei (AGN) display variable emission along
the whole electromagnetic spectrum. Different AGN classes and subclasses, in turn, are characterised by different amplitudes, duty-cycles, and time-scales
in their light-curves. While jetted AGN are in general more variable than
their non-jetted counterparts, those within the blazar class show the most
extreme behaviours. Optical microvariability (i.e., significant flux
variations on ours/minutes time-scales), in particular, has been used as a
powerful tool to test processes taking place in the innermost regions of AGN
jets. Systematic uncertainties affecting ground-based optical observations,
however, have led in the past to questionable claims of extreme
microvariability events. Moreover, and rather surprisingly, these
observational limitations have challenged our efforts to establish a firm and
reliable criterion to detect and quantify microvariability. I will review
here some results from studies of optical microvariability in AGN, carried out
by our group at FCAG/IALP and IAR along the last several years. Particular
attention will be paid to the influence of AGN host galaxies on
photo-polarimetric observations, and to the evaluation and re-assessment of
statistical tests usually applied to detect microvariability in optical
light-curves.
Extrasolar planet observations and analysis: recent advances and future
directions.
Rodrigo Díaz, Instituto de Astronomía y Física del Espacio, Argentina
Our understanding of extrasolar planets has been revolutionised in the last
two decades. Advances in the observational techniques and analysis methods
have permitted detections to move progressively from the regime of
Jupiter-like planets on close orbits –the easiest to detect and
characterise– to that of low-mass planets in the habitable zone of low-mass
stars. They also got us the first hints of extrasolar planet atmospheres. The
catalogue of planets amassed so far permitted improving our knowledge on
planet formation and evolution dramatically. At the same time, the huge
diversity of planets and system architectures also brought forth a myriad new
questions, some of which are among the most pressing ones in astrophysics. I will review the current state of the field, highlighting some of the most
recent advances and detections, and their importance for the future of the
field. Then, I will present some of the most relevant upcoming observational
projects. From the already-comissioned ESPRESSO spectrograph on the VLT, the IR instruments SPIRou and NIRPS, and the soon-to-be-launched NASA mission TESS, to the future PLATO space mission, these instrumental projects herald a new revolution. Coupled with state-of-the-art algorithms and data analysis techniques, they have the potential to produce the detection of hundreds of rocky planets in the habitable zone of their stars, and to provide new insights into on the quest for life outside the Solar System.
Gas dynamics and SMBH accretion in the Galactic centre
Jorge Cuadra, Universidad Católica de Chile
I will present numerical models of the gas dynamics in the inner parsec of the
Galactic centre. We follow the gas from its origin as stellar winds of around
30 observed young massive stars, until it is either captured by the central
black hole, or leaves the region. I will concentrate on two issues: the
influence of the expected outflow from the inner accretion flow, and the
creation of clumps that could explain the recently discovered cloud G2.
The Ancient Bulge
Sandro Villanova, Departamento de Astronomía, Universidad de Concepción, Chile
The Galactic Bulge has always been the most difficult part of the Milky Way to
study because of the presence of interstellar dust clouds that absorb almost
totally the visible light. However, today we have new instruments and new
technics that allow the astronomer to penetrate these clouds. In this talk I
will present the project we have in order to study the oldest and most
fascinating objects of this part of the Galaxy: the Bulge Globular Clusters.
We will take advantage of the infrared surveys that are carry on using
telescope facilities in Chile such as the VVV photometric survey, that is
mapping the Bulge area, and the APOGEE spectroscopic survey, that is observing thousands of stars in order to mapping its chemical pattern. In the context of the APOGEE survey, we have our our project, called CAPOS, that is devoted to the spectroscopic observation of a large sample of well known or recently discovered Bulge Globular Clusters. In addition, we are carrying on other observations at optical and infrared wavelengths, including high resolution spectroscopy using the VLT telescope and photometric observations using the HST telescope and other ground based adaptive optics facilities. The final aim is to obtain accurate chemical abundances and ages of the most representative Bulge Globular Clusters in order to shed light on the formation and the ancient history of this enigmatic part of the Milky Way.
Transitioning From Academia to Industry
Roberto Muñoz, Metric Arts & Pontificia Universidad Católica de Chile
The term Data Science has emerged recently to describe an interdisciplinary
field that combines statistics, data analysis and computer science. As
companies are collecting more and more data, they need to hire professionals
with the training and curiosity to make discoveries in the world of big data.
These professionals are called data scientists, and their sudden appearance on the business scene reflects the fact that companies are now wrestling with
information that comes in varieties and volumes never encountered before. In
this talk I will present how tech companies in Chile are spending more
resources in research and development, and how scientists are moving from
academic research to industry. I will list the main differences between the
academic and industrial research, what skills are the most valued by tech
companies and how young scientists can make the move to industry as smoothly and successful as possible.
Deep Learning for galaxy identification and detection.
Roberto González, Pontificia Universidad Católica de Chile
AstroCV is a computer vision library for processing and analyzing big
astronomical datasets. The current AstroCV library includes methods for the
tasks of object recognition, segmentation and classification, with emphasis in
the automatic detection and classification of galaxies. The underlying models
were trained using convolutional neural networks and deep learning techniques, which provide better results than methods based on manual feature engineering and SVMs. The detection and classification methods were trained end-to-end using public datasets such as the Sloan Digital Sky Survey (SDSS) and Galaxy Zoo, and private datasets such as the Next Generation Virgo (NGVS) and Fornax (NGFS) surveys. These methods are implemented in C and CUDA languages and makes intensive use of graphical processing units (GPU). Using a single high-end Nvidia GPU card, it can process a SDSS image in 50 milliseconds and a DECam image in less than 3 seconds. I will discuss other potential applications from real-time pipelines to Large Scale Structure. We provide the open source code, pre-trained networks and python tutorials for using the AstroCV library.
Ultra/Hyper-Compact HII Regions: Final Frontier or End of the Road?
Stanley Kurtz, Universidad Nacional Autónoma de Mexico
One of the earliest manifestations of a massive star is the ionization of the
surrounding molecular cloud material, forming an HII region. These regions
eventually grow in size, disperse the molecular cloud where they formed, and
become visible to optical telescopes. In their earlier stages, however, they
are very compact, and deeply embedded within the clouds, and are visible only
at radio and infrared wavelengths. At this stage they are known as
ultracompact HII regions. I give a short historical introduction to these
very young HII regions, mentioning some of their special physical
characteristics and the challenges they present to our understanding of the
star formation process. I also describe the more recent discovery of the even
smaller and denser hypercompact HII regions. Finally, I present the results
of the recent Very Large Array CORNISH survey, and speculate about what
remains to be learned of ultra and hyper-compact HII regions.
Working at the Argentinian Aerospace Industry
Axel Dente and Ivan Berdakin, INVAP S.E.
In this presentation we are going to talk about our experience working for
INVAP Aerospace Division. INVAP is an Argentinian company that started
developing technology for the nuclear sector in the early 70’s and expanded
into the Satellite industry at the beginning of the 90’s with CONAE as its
main customer. Since then, INVAP has manufactured scientific (SAC series and SAOCOM) and commercial (ARSAT) satellites, adapting their designs and
processes to the specific orbital characteristics and payloads, required by
each mission. This talk aims to introduce some particular aspects of
spacecraft manufacturing processes and quality requirements, in addition to a
description of the launch and operative mission phases. Finally we will
discuss some development tendencies in the space industry like
miniaturisation, satellite constellations and segmented architectures, and how
this affects local projects in the future.