Saskia Hekker (Max Planck Institute for Solar system research)
9/21/17, 9:00 AM
Victor Silva Aguirre (Stellar Astrophysics Centre, Aarhus University)
9/21/17, 9:15 AM
Asteroseismology is now delivering ages for red giants stars on a massive scale, and promises to set the standard for dating stellar populations as required to set up the chronology of the Milky Way disk formation. In this talk I will review the different observables and techniques involved in asteroseismic age determination for giants, focusing in the intrinsic precision and accuracy that can...
Cristina Chiappini (Leibniz-Institut für Astrophysik Potsdam)
9/21/17, 9:45 AM
Several all the processes at play in the formation of our Galaxy, such as gas accretion, internal secular evolution, and mergers. New data are unveiling the complexity and the interplay of the several stellar populations in each of the galactic components. A fully self-consistent model of the MW is still missing, but parallel efforts using different techniques have shown to be extremely useful...
Nadège Lagarde (Institut UTINAM)
9/21/17, 10:45 AM
The cornerstone mission, Gaia, together with complementary surveys (CoRoT, Kepler, APOGEE, Gaia-ESO) will revolutionize our understanding of the formation and history of our Galaxy, providing accurate stellar masses, radii, ages, distances, as well as chemical properties for very large samples of stars across different Galactic stellar populations.To exploit all potential of the combination...
Nathalie Themessl (Max Planck Institute for Solar System Research)
9/21/17, 11:00 AM
Oscillating red giants in open clusters provide tight constraints for testing theories of stellar structure and evolution. Through their oscillation spectra it is possible to deduce their stellar parameters (asteroseismology), while at the same time the stellar properties can also be determined independently through isochrones. We aim to verify the asteroseismic ages, computed using the same...
Dennis Stello (UNSW Sydney)
9/21/17, 11:15 AM
In this talk I will present the recent data analysis of the K2 Galactic Archaeology Program. I will include seismic inference of the stellar populations using spectroscopic data from the K2-HERMES survey. Finally, I will give prospects for what we can achieve for TESS in the frame-work of the TESS-HERMES survey, which has already observed about 30K stars in TESS' southern continuing viewing zone.
Monica Tosi (INAF - Osservatorio Astronomico di Bologna)
9/21/17, 11:30 AM
One of the main applications of stellar evolution models and galactic archeology is the derivation of the star formation histories (SFHs) of nearby galaxies from the Color-Magnitude Diagrams (CMDs) of their resolved stellar populations. SFHs are a key ingredient to understand galaxy evolution in general. This research field has made a tremendous step forward with the advent of HST, and is...
Charlie Conroy (Department of Astronomy, Harvard University)
9/21/17, 12:00 PM
In this talk I will discuss the unique insights provided by stellar ages on the build-up of the stellar halo and the disk of the Milky Way. I will present current ideas regarding the formation of these Galactic components and the progress that can be enabled by combining ages, abundances, and phase space information.
Pier-Emmanuel Tremblay (University of Warwick)
9/21/17, 12:30 PM
The vast majority of stars will become white dwarfs at the end of the stellar life cycle. These remnants are precise cosmic clocks owing to their well constrained cooling rates. Gaia Data Release 2 will detect up to 300,000 new white dwarfs, which will then be observed spectroscopically with WEAVE and 4MOST. By employing spectroscopically derived atmospheric parameters combined with Gaia...
Emanuele Dalessandro (Università di Bologna)
9/21/17, 1:00 PM
Two distinct populations with very different iron abundances, spanning a huge metallicity range (~1 dex) have been discovered in Terzan 5 (a globular cluster-like stellar system in the Galactic bulge). Thanks to the combination of AO-corrected ground-based observations and ultra-deep HST images, we have finally distinguished two MS-TO points, thus providing the age of the two populations: 12...
43. Temporal evolution of the elements in the context of GALAH: method description and preliminary results
Jane Lin (Research School of astronomy and astrophysics, ANU)
9/21/17, 4:00 PM
The field of Galactic archaeology is currently undergoing a revolution largely thanks to a new generation of ambitious spectroscopic surveys of >10e5 stars, such as APOGEE, GALAH and Gaia-ESO, producing copious amounts of high quality, high resolution observations. Galactic chemical evolution plays an important role in the interpretation and understanding of this expanding body of data, with...
Diego Bossini (University of Birmingham)
9/21/17, 4:15 PM
Asteroseismology allows us to measure the basic stellar properties of field giants observed far across the Galaxy. Most of such determinations are, up to now, based on simple scaling relations, involving the average large frequency separation (Dnu) and the frequency of maximum power (numax). In our work, we implement Dnu and the period spacing computed along detailed grids of stellar...
Marc Pinsonneault (Ohio State University, Dept. of Astronomy)
9/21/17, 4:30 PM
Asteroseismology permits us to infer masses for large samples of evolved red giant stars, which have also been the subject of comprehensive spectroscopic surveys. There is a strong correlation between the C/N ratio, mass and metallicity; this permits us to assign spectroscopic ages linked to a physical mechanism (the first dredge-up), as opposed to being a correlation. In this talk I...
Sofia Randich (INAF - Osservatorio di Arcetri)
9/21/17, 4:45 PM
I will review the Gaia-ESO Spectroscopic Survey, focusing on its potential to deliver, in combination with Gaia data, a major advance in stellar age calibration.
123. Alternative Stellar Evolutionary Paths in Open Star Clusters: Stars Whose Ages Aren't What They Seem
Robert Mathieu (Department of Astronomy, University of Wisconsin–Madison)
9/21/17, 5:15 PM
Open star clusters long have been fundamental benchmarks for stellar age determinations. And yet roughly 25% of the evolved stars in older open clusters do not fall on single-star isochrones, and age determinations for them in isolation would fail. I will review the status of observations, and consequent understanding, of blue stragglers, yellow giants, sub-subgiants and other stars of...
JJ Hermes (University of North Carolina at Chapel Hill)
9/21/17, 6:15 PM
With relatively simple evolution dominated by cooling, white dwarfs are excellent chronometers. Soon, Gaia will uncover hundreds of thousands of new white dwarfs, allowing us to date distinct components of the Milky Way with unprecedented precision. In order to maximize our results we need a more complete understanding of the interior structure of white dwarfs, especially their range of...
Thomas Constantino (University of Exeter)
9/21/17, 6:30 PM
We present the latest developments and scientific results from the compressible, hydrodynamic, time-implicit code MUSIC. MUSIC uses a preconditioned Jacobian-free Newton-Krylov method to efficiently model stellar interiors in 3D without being hindered by high memory requirements. MUSIC has realistic opacity and equations of state and is suited to low- to moderate-Mach number flows (1e-6 < M...
Jakob Mosumgaard (Stellar Astrophysics Centre, Aarhus University)
9/21/17, 6:45 PM
One of the key ingredients when determining the ages of stars is one-dimensional numerical models of stellar structure and evolution. However, many of today's stellar models share common shortcomings. To address this, we have consistently implemented results from 3D simulations of stellar atmospheres into the stellar evolution codes: GARSTEC, ASTEC, and MESA. Our implementation substitutes the...
93. Convective Core Overshooting and Ages: Probabilistic Constraints from Color–Magnitude Diagrams of LMC Clusters
Leo Girardi (Osservatorio Astronomico di Padova)
9/21/17, 7:00 PM
We present a framework to simultaneously constrain the values and uncertainties of the strength of convective core overshooting, metallicity, extinction, distance, and age in stellar populations. We then apply the framework to archival Hubble Space Telescope observations of six stellar clusters in the Large Magellanic Cloud that have reported ages between 1 and 2.5 Gyr. Assuming a canonical...
Jessica Kirkby-Kent (Keele University)
9/21/17, 7:15 PM
Detached eclipsing binary systems are often used to calibrate stellar evolutionary models, but require high precision to constrain free parameters such as convective overshooting and helium abundance. While overshooting can be constrained using asteroseismology, it is not currently possible to detect pulsations in all types of stars. Helium abundance can only be directly measured in hot stars....