38 research outputs found
Gaia & SSP libraries for Local Universe study.
We present the contribution that Gaia will offer to un-resolved stellar population studies. We start presenting the set of synthetic stellar libraries, computed ad hoc for Gaia, that we implemented in a SSP code using different set of isochrones and IMF. We illustrate the possible use of the resulting large set of SSPs in the analysis of systems far beyond the purposes of Gaia
DOOp, an automated wrapper for DAOSPEC
Large spectroscopic surveys such as the Gaia-ESO Survey produce huge
quantities of data. Automatic tools are necessary to efficiently handle this
material. The measurement of equivalent widths in stellar spectra is
traditionally done by hand or with semi-automatic procedures that are
time-consuming and not very robust with respect to the repeatability of the
results. The program DAOSPEC is a tool that provides consistent measurements of
equivalent widths in stellar spectra while requiring a minimum of user
intervention. However, it is not optimised to deal with large batches of
spectra, as some parameters still need to be modified and checked by the user.
Exploiting the versatility and portability of BASH, we have built a pipeline
called DAOSPEC Option Optimiser (DOOp) automating the procedure of equivalent
widths measurement with DAOSPEC. DOOp is organised in different modules that
run one after the other to perform specific tasks, taking care of the
optimisation of the parameters needed to provide the final equivalent widths,
and providing log files to ensure better control over the procedure. In this
paper, making use of synthetic and observed spectra, we compare the performance
of DOOp with other methods, including DAOSPEC used manually. The measurements
made by DOOp are identical to the ones produced by DAOSPEC when used manually,
while requiring less user intervention, which is convenient when dealing with a
large quantity of spectra. DOOp shows its best performance on high-resolution
spectra (R>20 000) and high signal-to-noise ratio (S/N>30), with uncertainties
ranging from 6 m{\AA} to 2 m{\AA}. The only subjective parameter that remains
is the normalisation, as the user still has to make a choice on the order of
the polynomial used for the continuum fitting. As a test, we use the equivalent
widths measured by DOOp to re-derive the stellar parameters of four
well-studied stars
FAMA: An automatic code for stellar parameter and abundance determination
The large amount of spectra obtained during the epoch of extensive
spectroscopic surveys of Galactic stars needs the development of automatic
procedures to derive their atmospheric parameters and individual element
abundances. Starting from the widely-used code MOOG by C. Sneden, we have
developed a new procedure to determine atmospheric parameters and abundances in
a fully automatic way. The code FAMA (Fast Automatic MOOG Analysis) is
presented describing its approach to derive atmospheric stellar parameters and
element abundances. The code, freely distributed, is written in Perl and can be
used on different platforms. The aim of FAMA is to render the computation of
the atmospheric parameters and abundances of a large number of stars using
measurements of equivalent widths as automatic and as independent of any
subjective approach as possible. It is based on the simultaneous search for
three equilibria: excitation equilibrium, ionization balance, and the
relationship between \fei\ and the reduced equivalent widths. FAMA also
evaluates the statistical errors on individual element abundances and errors
due to the uncertainties in the stellar parameters. The convergence criteria
are not fixed 'a priori' but are based on the quality of the spectra. In this
paper we present tests performed on the Solar spectrum EWs which tests the
dependency on the initial parameters, and the analysis of a sample of stars
observed in Galactic open and globular clusters.Comment: A&A accepted, 12 pages, 6 figures, 3 table
Interface Control Document for Gaia observed spectral libraries
disponible Ă http://www.obs.u-bordeaux1.fr/m2a/soubiran/dpac_doc.html2009, GAIA-C8-SP-UAO-UH-00
The Gaia satellite: a tool for Emission Line Stars and Hot Stars
The Gaia satellite will be launched at the end of 2011. It will observe at
least 1 billion stars, and among them several million emission line stars and
hot stars. Gaia will provide parallaxes for each star and spectra for stars
till V magnitude equal to 17. After a general description of Gaia, we present
the codes and methods, which are currently developed by our team. They will
provide automatically the astrophysical parameters and spectral classification
for the hot and emission line stars in the Milky Way and other close Local
Group galaxies such as the Magellanic Clouds.Comment: SF2A2008, session GAIA, invited tal
DOOp: DAOSPEC Output Optimizer pipeline
The DAOSPEC Output Optimizer pipeline (DOOp) runs efficient and convenient equivalent widths measurements in batches of hundreds of spectra. It uses a series of BASH scripts to work as a wrapper for the FORTRAN code DAOSPEC (ascl:1011.002) and uses IRAF (ascl:9911.002) to automatically fix some of the parameters that are usually set by hand when using DAOSPEC. This allows batch-processing of quantities of spectra that would be impossible to deal with by hand. DOOp was originally built for the large quantity of UVES and GIRAFFE spectra produced by the Gaia-ESO Survey, but just like DAOSPEC, it can be used on any high resolution and high signal-to-noise ratio spectrum binned on a linear wavelength scale
Synthetic Stellar libraries and SSP simulations in the Gaia Era
AbstractThe Gaia mission will obtain accurate positions, parallaxes and proper motions for 109object all over the sky. In addition, it will collect low resolution spectroscopy in the optical range for ~109objects, stars, galaxies, and QSOs. Parameters of those objects are expected to be part of the final Catalog. Complete and up-to-date libraries of synthetic stellar spectra are needed to train the algorithms to classify this huge amount of data. Here we focus on the use of the synthetic libraries of spectra calculated by the Gaia community to derive grids of Single Stellar Populations as building blocks of population synthesis models
MORFEO enters final design phase
MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations, formerly
MAORY), the MCAO system for the ELT, will provide diffraction-limited optical
quality to the large field camera MICADO. MORFEO has officially passed the
Preliminary Design Review and it is entering the final design phase. We present
the current status of the project, with a focus on the adaptive optics system
aspects and expected milestones during the next project phase