Found 17 talks width keyword stellar dynamics

Friday May 26, 2023
Dr. Sebastian F. Sanchez Sanchez
Universidad Nacional Autonoma de Mexico


We present the extended data release of the Calar Alto Legacy Integral Field Area (CALIFA) survey (eDR). It comprises science-grade quality data for 895 galaxies obtained with the PMAS/PPak instrument at the 3.5 m telescope at the Calar Alto Observatory along the last 12 years, using the V500 setup (3700-7500Å, 6Å/FWHM) and the CALIFA observing strategy. It includes galaxies of any morphological type, star-formation stage, a wide range of stellar masses ( ∼10^7-10^12 Msun), at an average redshift of  ∼0.015 (90\% within 0.005 < z <0.05). Primarily selected based on the projected size and apparent magnitude, we demonstrate that it can be volume corrected resulting in a statistically limited but representative sample of the population of galaxies in the nearby Universe. All the data were homogeneously re-reduced, introducing a set of modifications to the previous reduction. The most relevant is the development and implementation of a new cube-reconstruction algorithm that provides an (almost) seeing-limited spatial resolution (FWHM PSF  ∼1.0").  Furthermore we present the analysis performed using the pyPipe3D pipeline for these dataset. We include a description of (i) the analysis performed by the pipeline, (ii) the adopted datamodel for the derived spatially resolved properties and (iii) the catalog of integrated, characteristics and slope of the radial gradients for a set of observational and physical parameters derived for each galaxy. All these data has been distributed through the following webpage:

Thursday May 4, 2023
Dr. Paul Beck


Understanding stellar structure and evolution significantly impacts our understanding of the tight-knit evolution of galaxies and exoplanet systems. However, hidden behind the luminous layers of the stellar atmosphere, the deep interior of a star is eluding from direct measurements. The seismic study of waves propagating the deep interior provides the only way to measure the internal structure, dynamics, and mixing in any given star and compare it to theoretical models.

With the photometric data from space missions, such as the NASA Kepler telescope, a golden age has begun for seismology. In particular, the seismic studies of thousands of solar-like have led to numerous breakthroughs in our understanding of the stellar structure of red-giant stars. Complimentary information on stellar binarity, tidal forces, rotation, and lithium abundance provide additional constraints to characterize the advanced evolution of stars further and provide high-resolution insights into complex internal adjustments. Approaching a sample of ~1000 identified solar-like oscillators in binary systems, provided by the ESA Gaia and NASA TESS missions draws an exciting picture on the interaction of stellar and orbital evolution.
ID de reunión: 892 7515 0368

Código de acceso: 101169

Thursday February 23, 2023
Prof. Mauro D'Onofrio
University of Padova


I present a detailed analysis of the scaling relations of ETGs and suggest a way to predict the evolution of the distributions of galaxies in these planes. This new approach is able to account of several features observed in the FP projections and of the tilt of the Fundamental Plane.


Thursday October 13, 2022
Dr. Alexey Bobrick
Technion University, Israel


Exciting things may have happened sometimes to the stars we see in the sky today. For example, Betelgeuse, also known as Alpha-Ori, an M-type red supergiant, the 10th brightest sky in the sky (usually), may well have been a binary star in the past. Its rapid rotation, peculiarly large Galactic velocity, and unusual chemical abundances all point to it being kicked out from the birth environment and merging as a binary star. By comparing a Monte-Carlo stellar cluster population model with the observed populations of Galactic O- and B- type stars (progenitors of red supergiants), I will show that the story of Betelgeuse is not at all uncommon. In distant galaxies, closely related scenarios may give rise to peculiar core-collapse supernovae. I will conclude by briefly discussing how the diversity of such binary and triple stellar evolution histories reflects in the variety of the currently discovered core-collapse supernovae.

Tuesday September 20, 2022
Dr. Asif ud-Doula
Penn State University


Massive stars (at least eight times as massive as the Sun) possess strong stellar winds driven by radiation. With the advent of the so called MiMeS collaboration, an increasing number of these massive stars have been confirmed to have global magnetic fields. Such magnetic fields can have significant influence on the dynamics of these stellar winds which are strongly ionized. Such interaction of the wind and magnetic field can generate copious amount of X-rays, they can spin the star down, they can also help form large scale disk-like structures. In this presentation I will discuss the nature of such radiatively-driven winds and how they interact with magnetic fields.

Thursday May 12, 2022
Dr. Eugene Vasiliev
IoA Cambridges


I discuss the dynamical interactions between the Milky Way and its satellite galaxies, focusing on the closest and most massive satellites - the Large Magellanic Cloud (LMC) and the Sagittarius dwarf galaxy. The former just has had its first close encounter with the Milky Way very recently, and the latter has been orbiting our Galaxy for several Gyr and is tidally disrupting, leaving a prominent tidal stream spanning the entire sky. Thanks to the abundant and precise observational data from the Gaia satellite and various spectroscopic surveys, we now have a very detailed view of the Sagittarius stream and the remnant. It appears that to reproduce its observed properties, one needs to take into account the gravitational effect of the LMC itself and the effect that it produces on the motion of the Milky Way: an intricate dance of three galaxies. The LMC also affects the motion of other streams and satellite galaxies in the outskirts of the Milky Way, and I discuss an approach for compensating these perturbations in the context of dynamical modelling of the Milky Way mass distribution and the analysis of satellite orbits.

Thursday January 27, 2022
Prof. Axel Brandenburg
Nordita (Sweden)


Following Cowling's anti-dynamo theorem of 1933, there was a long period during which the very existence of dynamos was unclear. Even with the emergence of three dimensional simulations in the late 1980s, people were careful to distinguish true dynamos from just some sort of amplification. Meanwhile, we know of many examples of true dynamos - not only from simulations, but also from several laboratory experiments. Nevertheless, there are still problems, fundamental ones and also very practical ones. After all, we are really not sure how the solar dynamo works. Today, global three-dimensional simulations seem to have an easier time to reproduce the behaviors of superactive stars, but not really the group of inactive stars, to which also the Sun belongs. The Sun itself may actually be special; it has so well defined cycles and it is at the brink of becoming very different. Theoretically, slightly slower rotators should have antisolar rotation, but it is possible that some of those stars never become that slow if stellar breaking ceases for some reason. Sun and starspots are very evident indicators of solar and stellar activity. Their formation is also not well understood. Polarimetry reveals their magnetic helicity, which can be detected even with the solar wind.

Tuesday January 25, 2022
Drs. Sarah Martell
Australian National University


The field of Galactic archaeology has been very active in recent years, with a major influx of data from the Gaia satellite and large spectroscopic surveys. The major science questions in the field include Galactic structure and dynamics, the accretion history of the Milky Way, chemical tagging, and age-abundance relations. I will give an overview of GALAH as a large spectroscopic survey, and describe how it is complementary to other ongoing and future survey projects. I will also discuss recent science highlights from the GALAH team and compelling questions for future work.

Tuesday November 23, 2021
Dr. Dainis Dravins
Lund Observatory (Sweden)


The new generation of spectrometers designed for extreme precision radial velocities enable correspondingly precise stellar spectroscopy. It is now fruitful to theoretically explore what the information content would be if stellar spectra could be studied with spectral resolutions of a million or more, and to deduce what signatures remain at lower resolutions. Hydrodynamic models of stellar photospheres predict how line profiles shapes, asymmetries, and convective wavelength shifts vary from disk center to limb. Corresponding high-resolution spectroscopy across spatially resolved stellar disks is now practical using differential observations during exoplanet transits, thus enabling the testing of such models. A most demanding task is to understand and to model spectral microvariability toward the radial-velocity detection of also low-mass planets in Earth-like orbits around solar-type stars. Observations of the Sun-as-a-star with extreme precision spectrometers now permit searches for spectral-line modulations on the level of a part in a thousand or less, feasible to test against hydrodynamic models of various solar features.

Tuesday June 8, 2021
Dr. Hector Socas-Navarro


In this talk I'll present results from a recent paper in which we have developed a new analysis technique for solar spectra based on artificial neural networks. Our first test applications yielded some unexpected and interesting results. The fine-scale network of temperature enhancements in the quiet middle and upper photosphere have a reversed pattern. Hot pixels in the middle photosphere, possibly associated with small-scale magnetic elements, appear cool at higher levels (log(tau)=-3 and -4), and vice versa. We also find hot arcs on the limb side of magnetic pores, which we interpret as the first direct observational evidence of the "hot wall" effect. Hot walls are a prediction of theoretical models from the 1970s which had not been observed until now.

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