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Gaia

Wed, 2007-09-26 20:48, František Fárník

BRIEF DESCRIPTION OF THE PROJECT

Gaia is an ESA mission scheduled for launch in 2011. The mission is designed to obtain extremely precise astrometry, photometry, low and medium resolution spectra for a huge sample of objects (see www.esa.int/esaSC/120377_index_0_m.html).The satellite will bring information on positions, distances, space motions, and many physical characteristics of some one billion stars in our Galaxy and beyond. This will allow our Galaxy to be mapped, for the first time, in three dimensions. Astrometric accuracies of around 20 microarcsec at 15 mag should lead to 20 million of stars measured with distant accuracies of better than 1 per cent, and more than 100 million better than 5 per cent. The photometric survey should be complete to V=20 over the whole sky. Tangential velocities will be measured astrometrically at better than 1 kms-1 for about 100 million stars, while dedicated radial velocity spectrometer (RVS) will gather radial velocities to 1 – 10 kms–1 to 16 – 17 mag. Each star will be visited up to eighty times during the five-year mission life-time.
The important aspect of the Gaia project are the ground-based observations, to be carried before and after the launch of the satellite. While the latter represents a typical follow-up observations needed to confirm and/or broaden the knowledge about a specific object obtained from the satellite data, the pre-launch ground-based observations are needed for calibration purposes (absolute flux calibration for Gaia photometry, definition of the zero-point of radial velocities measured with RVS instrument). Ground-based observations will be needed to characterize several kinds of variable objects. Many observations related to Gaia project have been already realized. Very often, there are dispersed in particular archives or even in publications only. A compilation effort is then necessary. The other task of the ground-based segment is to provide “training” data. This task includes generation of synthetic spectra, calibration of training data, and assembling of training data grids. For the calibration purposes, definition of a grid of reference stars with accurately and homogeneously determined astrophysical parameters is needed.

Gaia is a very important scientfic project which will deeply influence the evolution of astronomy and astrophysics in the next decade(s). It is thus quite natural that also teams in the Czech Republic related to specific object studies and to data processing expressed their desire to be ivolved in the Gaia mission. The Czech participation in Gaia is defined in the following main lines, with relevant responsible scientists.

WP1: Ground-based observation in Gaia pre and post-launch time (Pavel Koubský)
The 2m telescope will perform pre-launch spectroscopic supplementary observations for Specific Object Studies (GWP-M-720-0000) in cooperation wit G. Clementini (GWP-M-732-0000). With planned improvement of the 2m telescope and its spectrograph there is a good chance to participate in the follow-up observations in Gaia programme.

WP2:Reduction of reference star spectra ( Pavel Koubský)
Perform detailed analysis of stellar spectra with up-to-date methods and line lists in order to determine accurate and homogeneous astrophysical parameters of the calibrators.

WP3:Gaia CU7 sub-workpackage on Eruptive stars with emphasis on Be stars (Pavel Koubský)
Create a catalogue of known and suspected Be stars so that the Gaia observations can effectively improve our knowledge of this sample. This catalogue will be constructed in the form of a computer database and will contain information that will help to sort out common properties. These commo properties will be then subject of theoretical analysis base on grid of synthetic spectra and integral fluxes. Tools developped in this WP are to be applied to other type of eruptive stars.

WP 4: Gaia Software development ( Pavel Koubský)
Direct participation in the Gaia CU7 Data Processing Centre activity. After the launch of Gaia this WP can be broadened to scientific activities connected with data analysis, data archiving, data interpretation and publications. In this phase, which will continue beyond the scope of this proposal, the participation of more people should be considered.

WP5:Gaia CU7 sub-workpackage on Cataclysmic Variables ( René Hudec)
The investigation and analyses of Cataclysmic Variables and related objects (including supernovae, various classes of novae, polars and symbiotic stars) based on Gaia photometry and spectrophotometry as well as complex analyses with addional data.

WP6:Gaia CU7 sub-workpackage on Optical Counterparts of High-Energy Sources (René Hudec)
The investigation and analyses of optical counterparts of high energy sources ( X-ray binaries, optical transients, optical afterglows related to x-ray flashes an gamma-ray bursts and microquasars).based on Gaia data as well as complex analyses with addional data.

WP7: Special Variability Detection and Variability Characterization (René Hudec)
Participation in Special Variability Detection and Variability Characterization. Feasibility study of variability detection methods in spectrophotometry using simulated low dispersion Gaia data and simulated real data provided by digitised spectral Schmidt plates with objective prisma including design and development and tests of relevant algorithms and software. Designing and developing of novel algorithmes for processing of low dispersion spectra (participation of undergraduate and/or PhD students)

WP8: Simultaneous observations by robotic telescopes (René Hudec)
The Gaia analyses will be also supported by optical observations provided by the robotic telescopes and monitors (BOOTES, BART, CCD telescopes, etc.), in agreement with the requirements of the relevant workpackage for supporting ground-based observations within the CU7.

 

Principal Investigator :             Pavel Koubský
Address                    :             Astronomický ústav AV ČR
                                              251 65 Ondřejov
                                              koubsky@sunstel.asu.cas.cz

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