Found 7 talks width keyword Gaia
Time-domain space missions have revolutionized our understanding of stellar physics and stellar populations. Virtually all evolved stars can be detected as oscillators in missions such as Kepler, K2, TESS and PLATO. Asteroseismology, or the study of stellar oscillations, can be combined with spectroscopy to infer masses, radii and ages for very large samples of stars. This asteroseismic data can also be used to train machine learning tools to infer ages for even larger stellar population studies, sampling a large fraction of the volume of the Milky Way galaxy. In this talk I demonstrate that asteroseismic radii are in excellent agreement with those inferred using Gaia and spectroscopic data; this demonstrates that the current asteroseismic data is precise and accurate at the 1-2% level. Major new catalogs for Kepler and K2 data are nearing completion, and I present initial results from both. We find unexpected age patterns in stars though to be chemically old, illustrating the power of age information for Galactic archeology. Prospects for future progress in the TESS era will also be discussed.
The existence of apparently isolated massive stars has been recognized for some time, and various explanations have been proposed to explain these ranging from isolated star formation to variouscluster ejection mechanisms. In this talk I will present recent results from Gaia and Hubble on stellar dynamics within the Tarantula Nebula/30 Doradus region of the Large Magellanic Cloud. I will discuss how these complementary datasets have improved our knowledge of this nearby mini-starburst. The first results indicate the existence of a few stars in the region with masses ~100 solar masses that have been ejected from the central dense cluster R136. Ejection velocities appear torange from a few 10s of km/s to ~100 km/s. Given the extreme youth of R136 it is therefore likely that the mechanism of ejection was via the dynamical interaction channel rather than the binary supernova ejection scenario.
By providing information on distances and proper motions for one billion stars, the Gaia satellite allows us to investigate the major unsolved challenges in galaxy formation: the nature of dark matter, the origin of Galactic spiral activity and its relation to the bar, and more generally the history of the Milky Way.
My research aims to develop a theoretical approach to modeling and exploiting the big data and address problems at the forefront of Galactic Dynamics at various scales. What is the origin of the spiral activity in the Milky Way? How are all of these perturbations to the structure of the Galaxy coupled to each other directly and through the dark-matter halo? I will also present my ongoing work on statistical techniques of big-data analysis and advanced numerical simulations used to interpret the evolution of star clusters and discover streams in the stellar disk of the Milky Way.
Galactic Archeology is today a vibrant field of research. The adoption and launch of the Gaia astrometric satellite by ESA has resulted in many spectroscopic Galactic surveys that aim to complement the Gaia data with information (for the fainter Gaia stars) about stellar elemental abundances, radial velocities, and stellar parameters. This results in multi-dimensional data sets which will allow us to put the Milky Way stellar populations into a much broader galactic context, eg by comparing with models and galaxies at large look-back times. In this talk I will review a selection of recent exciting developments in Galactic Archeaology found via on-going surveys as well as look to the future and see what surveys like 4MOST and WEAVE will bring. The proposed surveys will be put into a wider context of past, on-going and future spectroscopic surveys and how this can all be combined to understand the Milky Way as a galaxy.
Gaia - the ESA cornerstone astrometric mission - was launched in December 2013, with the goal of censing the Milky Way population in a 6D space (positions and velocity) of 10^9 point-like obects, with errors
100-1000 times smaller than Hipparcos, with three color magnitudes and spectra as well. The scientific impact of its data will be large in many fields of astrophysics, from Galactic science, to Solar system objects, to stellar astrophysics, to galaxies and Quasars; from the distance ladder revision to fundamental physics. I will describe the mission concept, the scientific goals, and the present status of the mission, with special attention to the flux calibration of Gaia data.
AbstractWe present recent theoretical and empirical results concerning the accuracy of Cepheid distance estimates based on optical and near-infrared (NIR) Period-Luminosity (PL) relations. In particular, we plan to discuss the dependence of both slope and zero-point on the metal content using a large sample of extragalactic Cepheids. Moreover, we discuss pros and cons of optical and NIR reddening free Period-Wesenheit relations. We also mention the impact that GAIA will have on the precision of the Cepheid distance scale and the role that E-ELT will play in the identification of Cepheids beyond the Local Volume.
AbstractThe study of the Milky is expected to have a major impact on our understanding of how galaxies form and evolve. "Near-field cosmology" is being vigorously pursued through a series of major surveys of the Galaxy's stellar content (2-MASS, SDSS, RAVE, Hermes, Apogee, Gaia) that are either in hand or pending. It will be argued that what we want to know is deeply buried in these data and can only be extracted by comparing the surveys with a hierarchy of dynamical models of ever increasing complexity. Work currently being done to build such hierarchical models will be described, and some early results from this work will be summarised.
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