A photometric study of the intermediate age open cluster King 5

We report on near IR (J and K bands) observations of an $8^{\prime} \times 8^{\prime}$ region centered on the poorly studied open cluster King 5, for which only optical photometry existed. We found that the cluster is of moderate age (1.0 Gry old), intermediate in age between the Hyades and NGC 752. Combining optical and IR photometry we obtain estimates for cluster parameters. The color excess E(J-K), E(V-I) and E(V-K) are 0.50, 1.10 and 2.45, respectively. The true distance modulus turns out to be $(m-M)_0) = 11.40\pm 0.15$. As a consequence, King 5 is 1.9 kpc far from the Sun.Comment: 7 pages, 6 eps figures, accepted for pubblication in Astronomy and Astrophysic

The Future of Astrometry in Space

This contribution focuses on the importance of astrometry and on its future developments. Over the centuries astrometry has greatly contributed to the advance of the knowledge of the Universe. Nowadays a major breakthrough is on the way due to astrometric sky surveys from space. ESA space missions Hipparcos first and then Gaia point out the outstanding contribution that space astrometry can provide to our knowledge in many fields of astrophysics, going from the Milky Way formation and evolution, to stellar astrophysics, extra-galactic astrophysics, and fundamental physics. We briefly outline the properties of Gaia first and second data release, and the accuracies expected end-of-mission. The next big advance in space astrometry would be either to improve the astrometric accuracy of one order of magnitude, or to move to a different wavelength domain. While both options have the potential to bring us in a new era of discovery, they have to face enormous issues. We summarize the future directions in space astrometry that are proposed or under investigation by the scientific community, their main challenges and the expected outcome

Near-infrared photometry of the young open clusters NGC 1893 and Berkeley 86

We present photometry in the J and K near-infrared bands for two regions centered on the young open clusters NGC 1893 and Berkeley 86. We study 700 stars down to K = 17 in the field of NGC 1893, and about 2000 stars in the field of Berkeley 86 down to K$\sim$ 16.5, for which near-infrared photometry was insofar not available. Coupling J-K data with UBV photometry taken from literature, we produce reddening corrected colour-magnitude diagrams. We find that our data are consistent with previous determinations: the clusters are roughly coeval with an age between 4 and 6 million years. The mean reddening (measured as E(J-K)) values turn out to be 0.35 and 0.50 for NGC 1893 and Berkeley 86, respectively.Using colour-colour plots we discuss the presence of candidate pre-main sequence stars showing infrared excess. Candidates are found in both cluster regions, confirming the young age of these clusters.Comment: 9 pages, 12 figures, Astronomy & Astrophysics Main Journal Accepte

Gaia first data release and beyond

The first Gaia data release took place in 2016, delivering astrometry and photometry for more than 1 billion sources in our Galaxy. After almost one year, Gaia data have already become the reference for astrometry, with applications in a wide range of topics. In this paper we summarize the impressive quality and the known limitations of the data; and we present the extensive validation work that was done by the Gaia Consortium before publication. We review a few results based on Gaia first data release, while looking ahead at the upcoming second data releas

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