Found 6 talks width keyword high-mass stars

Thursday November 9, 2023
National Astronomical Observatory of Japan



Magnetism is ubiquitous in the Universe, yet understanding the magnetic properties of stars continues to present intriguing challenges. Recent advancements owe their success to large-scale optical spectropolarimetric surveys, asteroseismic inferences, and new modelling methodologies. This presentation focuses on the evolution of massive stars with OB spectral types, with a particular emphasis on the incorporation of magnetic field effects into one-dimensional (1D) evolutionary model calculations. We explore the distinctiveness of these magnetic models in contrast to their non-magnetic counterparts, shedding light on the substantial influence of large-scale, organized magnetic fields on the physical characterization of stars. In particular, we investigate surface phenomena, such as mass loss and angular momentum loss, and their profound impact on the evolutionary trajectories of hot, massive stars. We will conclude by outlining future avenues to improve 1D models and addressing some of the remaining challenges in describing the magnetic characteristics of stars. 

Thursday May 4, 2023


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 October 13, 2022
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.

Thursday November 19, 2020
KU Leuven (Belgium)


Massive stars are often found to be in pairs. This configuration is both a blessing and a curse. From it, we can estimate their exact properties such as their masses but the interactions that result during their life considerably affect the way that the stars evolve.

Here, we provide an overview of progresses made through a number of medium and large surveys. These results provide new insights on the observed and intrinsic multiplicity properties of massive stars through a large range of masses and at different metallicities. Furthermore, to understand how the stars evolve when they are in pair and what are the effects of these interactions on the stellar properties, we undertook a large study of more than 60 massive binaries at Galactic and LMC metallicities using spectral disentangling, atmosphere modelling and light curve fitting to determine their stellar parameters, and surface abundances. This unique dataset is the largest sample of binaries composed of at least one O-type star to be studied in such a homogeneous way. It allows us to give strong observational constraints to test theoretical binary evolutionary tracks, to probe rotational and tidal mixings and mass transfer episodes.

Wednesday November 13, 2013
Institute for Astronomy, University of Hawaii at Manoa


The determination of chemical composition and distances of galaxies is crucial for constraining the theory of galaxy formation and evolution in a dark energy and cold dark matter dominated universe. However, the standard technique using HII regions to determine the metallicity of star forming galaxies, nearby and at high redshift, is subject to large systematic uncertainties that are poorly understood and the determinination of accurate distances using Cepheids suffers from uncertainties caused by the metallicity dependence of the period luminosity relationship and extinction and crowding corrections. Multi-object spectroscopy of blue and red supergiant stars - the brightest stars in the universe at visual and NIR wavelengths - provides an attractive alternative. I will present results accumulated over recent years for galaxies in the Local Group and beyond out to a distance of 8 Mpc and will discuss the potential of future work with TMT and E-ELT. Combining the photon collecting power of these next generation telescopes with Adaptive Optics we will be able to study individual supergiant stars in galaxies as distant as the Coma cluster. With spectroscopy of the integrated light of young very massive Star Super Clusters and simple population synthesis techniques we can reach out ten times further.

Thursday January 19, 2012
Bartol Research Institute, University of Delaware, USA


Massive stars lose mass through powerful, radiatively driven stellar winds. Building on the original "CAK" model for steady, spherical winds driven by line-scattering, this talk will review recent research on the multi-faceted nature of such wind mass loss under varied conditions, for example due to rapid rotation, magnetic channeling, binary interaction, or a luminosity near the Eddington limit. An overall theme is that wind mass loss can in this way lead to a wide variety of astrophysical phenomena, including bipolar nebulae, massive star magnetospheres, colliding winds or compact companion accretion, and luminous blue variable eruption. The discussion here will summarize these with an emphasis on their varied observational signatures.

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