Image of the Week
A new heart for the Gaia Object Generator
|The new Galactic Thin Disc Hess Diagram ready to be integrated in the Gaia Object Generator (Luri et al. 2014). It shows the stellar density in the Solar Neighbourhood distributed in temperature and brightness, and split in age intervals from 0 to 10 Gyrs. The signature of the stellar evolution can be clearly seen. The diagram was simulated using the Besançon Galaxy Model (Robin et al. 2003) with the Galactic Thin Disc treatment from Czekaj et al. (2014). It represents a big improvement in the generation of important Galaxy tracers, such as giant stars at different stages of evolution (i.e., Red Clump), and also in pre-main sequence stars at low masses for the youngest populations. White Dwarfs are treated separately and thus not included here.|
The first Gaia data release, scheduled for end of the summer 2016, is going to revolutionise the study of Galactic structure and evolution. As part of its preparation, the Data Processing and Analysis Consortium (DPAC) Coordination Unit 9 is in charge of guaranteeing that the data has passed a set of quality tests. These tests ensure that the published data are valid for scientific exploitation. The Besançon Galaxy Model (Robin et al. 2003, 2012), which is integrated in the Gaia Object Generator (GOG, Luri et al. 2014), is being used as a tool for Gaia data validation tests. A new run of GOG, to be executed by the Barcelona team, is expected for February 2016. It will provide a simulation of the full sky as seen by Gaia, using, at its heart, the new Galactic Thin Disc Hess Diagram presented in the above figure. This simulation will be used for Gaia data validation, in the data archive, and for scientific exploitation.
Note: DPAC will be releasing its own estimates of stellar parameters, starting in Gaia-DR2 (see CU8 paper by Bailer-Jones et al. 2013).
Credits: ESA/Gaia/DPAC/CU2/R. Mor (ICCUB-IEEC, Barcelona University), A.C. Robin (OSU THETA and Institut UTINAM, Besançon), F. Figueras (ICCUB-IEEC, Barcelona University)
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