Rationale
The Milky Way is a rich laboratory that we can use to explore how stars and galaxies form, how they evolve, and which processes shape their present states. Stars harbour planets, and our planetary system provides pointers to extra-solar worlds. Making linkages from the local solar neighbourhood, to planetary systems, open clusters, the disk, and our Galaxy as a whole, is the key to our understanding of the wider evolution of the Universe from the Big Bang to its eventual cold and lonely demise.
This topic is timely. Not only because the school will take place at about the same time as the launch of the Gaia spacecraft, butalso due to the abundant and important on-going research on the Milky Way as a galaxy: the two phases of the Galactic disk, the structure of the stellar halo, the detailed morphology of the inner regions, the connection between the long bar and the bulge, etc. In addition, there is an ever increasing interest in surveying the Galaxy from many different angles – consider the large area surveys being devoted to the Milky Way since the last decade: 2MASS, APOGEE, SEGUE, RAVE, Gaia, the Gaia-Eso Survey, and others.
The broad topic of the school can be better understood when separated into areas, as described below. This school will be very tightly linked to the scientific exploitation of the Gaia mission.
The Stellar Constituents of the Milky Way. Unraveling the structure, formation, and evolutionary history of the Milky Way builds on a detailed understanding of the stars that make up our Galaxy. The school will focus on two central aspects of this: 1) where do the stars form and 2) what are their astrophysical properties. Gaia's contribution to these fields will be enormous, as the mission will directly observe 1,000 million stars and measure their astrophysical properties. This enables a detailed interpretation of the phase-space data in terms of specific events that have shaped the Milky Way as well as a detailed discussion of how and where star formation took place.
Based on the study of star forming regions, stars are thought to form primarily in open clusters or associations. This scenario may explain a large part of the stellar population of the thin disk. However, the formation of the thick disk is still hotly debated with at least five different, non-exclusive, scenarios currently being discussed in the literature: accretion, heating, radial migration, gas-rich mergers, and the conversion of unstable young disks into a thick disk and bulge system. Current data for the Milky Way disks and bulge are not able to distinguish between these scenarios conclusively, at least given the available analysis tools. Gaia data will hopefully disentangle the origin of the Milky Way’s disk stars through a detailed study combining the 6D phase space information with accurate elemental abundances from Gaia's instruments and supporting surveys (Gaia-ESO, APOGEE, HERMES, etc.). This school aims at getting the next generation of scientists ready for this data revolution, and to ensure that the potential of Gaia, and its complementary observations, is fully realized.
Galactic Dynamics are best traced by the motions of the Milky Way’s stars and gas. Gaia will focus on stellar motions, which are key for uncovering the properties of the different stellar components of our Galaxy, such as their size, mass, and density. Galactic dynamics are an excellent means for deriving the detailed mass distribution of the Milky Way and constraining the distribution and amount of dark matter. Dynamics are also a vital tool for uncovering stellar streams in phase space and for finding signatures of ancient accretion events. A key challenge will be to create a realistic Galaxy model based on Gaia's 1,000 million star catalogue. This school will underline the most useful dynamical tracers in the Milky Way, focusing on getting students ready for squeezing the most out of Gaia, and connecting observations in the Milky Way with other galaxies with more complex dynamics.
This school is as part of the training programme of GREAT-ITN that we are organising in Tenerife (Canary Islands, Spain) devoted to provide the students with a deep knowledge on the several topics treated in the programme. In addition, the participants will have the opportunity to present their research topics and discuss with a panel of distinguished senior researchers.
The School programme will be organized around the following broad subjects:
- Dynamics of the Milky Way
- Simulations (N-body and others)
- Chemical abundances
- Stellar populations: compositions, kinematics and morphology
- Galactic Surveys
- Stellar distribution models
Local Organizing Committee: F. Garzón, C. Allende Prieto, C. Gallart and M. López-Corredoira from Instituto de Astrofísica de Canarias (IAC), Tenerife, Spain