A revolution in stellar physics with Gaia and large surveys

ESO Workshop: A revolution in stellar physics with Gaia and large surveys


The era of Gaia-enabled revolutions in almost all areas of astrophysics has started. In particular, and crucially, Gaia exquisite astrometry and photometry combined with data of other large stellar surveys, from the ground and from space, are going to allow major progress in our understanding of stellar physics.

Stellar evolution is successful in describing the general aspects of the life of stars, nevertheless, many physical processes remain poorly understood. A correct and detailed description of stellar evolution has a fundamental impact on the comprehension of the formation of planetary systems and stars, and thus also on both Galactic and extra-galactic science.

The Gaia revolution in stellar physics starts with parallaxes giving precise distances and resulting in precise luminosities for >109 stars. Joining luminosities with temperatures and/or colours, from Gaia itself and from different surveys, it will be possible to position these stars with very high precision in the HR diagram. Precise luminosities and temperatures further allow the determination of stellar radii, a quantity otherwise poorly constrained.

Predicting the correct properties and position of a star in the HR diagram, plus the evolution of those properties, requires models to include many physical data and processes as, for example, equations of state, nuclear reaction rates, opacities, stellar rotation, mechanisms of energy and material transport. Despite great progress in theoretical developments, high quality observations are key to guide accurate stellar modelling and to highlight where the model assumptions fail.

Open issues in the modelling of stars of different mass and in different evolutionary stages include, for example, the efficiency of angular momentum and material transport, the role of magnetic fields, the timescales and mechanisms of rotational braking.

The workshop will focus on discussions about the advances in our understanding of stellar physical processes made possible by combining the astrometry and photometry of Gaia with data of other large photometric, spectroscopic, and asteroseismic stellar surveys. Asteroseismology, in particular, has been essential to allow access to information coming from the interior of stars. These combined data will permit detailed studies of stellar physics to a level that is unprecedented in the history of stellar astrophysics.

Improvements in stellar models will also enable stellar age determination. With ages available for large stellar samples, we will move beyond studying snapshots of stellar evolution to studying complete histories of the evolution of stellar properties with time.

Moreover, the large sample seen by Gaia will encompass many peculiar and rare objects including some undergoing rapid evolutionary effects, binaries undergoing all sorts of interactions, and pulsating stars of different types. This has a huge potential for new astrophysical discoveries and for uncovering new physical processes.

The goal of this workshop is to bring together the community that is working on fulfilling this promise of a revolution in stellar physics. The discussions will focus on the advances in stellar physics made possible from the combination of Gaia and large surveys. Attention will also be given to future missions and surveys that will either explore new types of data (polarimetry, different wavelength windows...), improve the precision of measurements, or enlarge samples and data coverage.

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Header image depicts part of a preliminary colour map of the sky from Gaia mission. Courtesy: ESA/Gaia/DPAC/CU5/DPCI/CU8/F. De Angeli, D.W. Evans, M. Riello, M. Fouesneau, R. Andrae, C.A.L. Bailer-Jones (original image)