P. Di Marcantonio

Synthetic Lick Indices and Detection of α-Enhanced Stars

Synthetic Lick indices computed with solar scaled abundances and with α-element enhancement are presented and compared with predictions from both theoretical computations (Tripicco & Bell; Thomas, Maraston, & Bender; Barbuy et al.) and empirical fitting functions (de Freitas Pacheco). We propose selected combinations of indices capable of singling out α-enhanced stars without requiring previous knowledge of their main atmospheric parameters. By applying this approach to the 460 stars in the Worthey et al. catalog, we detected a list of 82 candidate α-enhanced stars. The confirmation of α-enhancement was obtained by searching the literature for individual element abundance determinations from high-resolution spectroscopy for a subsample of 34 stars. Preliminary discussion of the properties of the detected α-enhanced stars with respect to their [Fe/H] values and kinematics is presented.

Metallicity Determinations from Ultraviolet-Visual Spectrophotometry. I. The Test Sample

New visual spectrophotometric observations of non-supergiant solar neighborhood stars are combined with IUE Newly Extracted Spectra (INES) energy distributions in order to derive their overall metallicities, [M/H]. This fundamental parameter, together with effective temperature and apparent angular diameter, is obtained by applying the flux-fitting method while surface gravity is derived from the comparison with evolutionary tracks in the theoretical H-R diagram. Trigonometric parallaxes for the stars of the sample are taken from the Hipparcos Catalogue. The quality of the flux calibration is discussed by analyzing a test sample via comparison with external photometry. The validity of the method in providing accurate metallicities is tested on a selected sample of G-type stars with well-determined atmospheric parameters from recent high-resolution spectral analysis. The extension of the overall procedure to the determination of the chemical composition of all the INES non-supergiant G-type stars with accurate parallaxes is planned in order to investigate their atmospheric temperature structure.

EELT-HIRES the high-resolution spectrograph for the E-ELT

The first generation of E-ELT instruments will include an optic-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long phase A study for EELT-HIRES has just started and will be performed by a consortium composed of institutes and organisations from Brazil, Chile, Denmark, France, Germany, Italy, Poland, Portugal, Spain, Sweden, Switzerland and United Kingdom. In this paper we describe the science goals and the preliminary technical concept for EELT-HIRES which will be developed during the phase A, as well as its planned development and consortium organisation during the study.

Application development using the ALMA common software

The ALMA Common Software (ACS) provides the software infrastructure used by ALMA and by several other telescope projects, thanks also to the choice of adopting the LGPL public license. ACS is a set of application frameworks providing the basic services needed for object oriented distributed computing. Among these are transparent remote object invocation, object deployment and location based on a container/component model, distributed error, alarm handling, logging and events. ACS is based on CORBA and built on top of free CORBA implementations. Free software is extensively used wherever possible. The general architecture of ACS was presented at SPIE 2002. ACS has been under development for 6 years and it is midway through its development life. Many applications have been written using ACS; the ALMA test facility, APEX and other telescopes are running systems based on ACS. This is therefore a good time to look back and see what have been until now the strong and the weak points of ACS in terms of architecture and implementation. In this perspective, it is very important to analyze the applications based on ACS, the feedback received by the users and the impact that this feedback has had on the development of ACS itself, by favoring the development of some features with respect to others. The purpose of this paper is to describe the results of this analysis and discuss what we would like to do in order to extend and improve ACS in the coming years, in particular to make application development easier and more efficient.

Adoption of new software and hardware solutions at the VLT: the ESPRESSO control architecture case

ESPRESSO is a fiber-fed cross-dispersed echelle spectrograph which can be operated with one or up to 4 UT (Unit Telescope) of ESOs Very Large Telescope (VLT). It will be located in the Combined-Coudé Laboratory (CCL) of the VLT and it will be the first permanent instrument using a 16-m equivalent telescope. The ESPRESSO control software and electronics are in charge of the control of all instrument subsystems: the four Coudé Trains (one for each UT), the front-end and the fiber-fed spectrograph itself contained within a vacuum vessel. The spectrograph is installed inside a series of thermal enclosures following an onion-shell principle with increasing temperature stability from outside to inside. The proposed electronics architecture will use the OPC Unified Architecture (OPC UA) as a standard layer to communicate with PLCs (Programmable Logical Controller), replacing the old Instrument Local Control Units (LCUs) for ESO instruments based on VME technology. The instrument control software will be based on the VLT Control Software package and will use the IC0 Field Bus extension for the control of the instrument hardware. In this paper we present the ESPRESSO software architectural design proposed at the Preliminary Design Review as well as the control electronics architecture.

Optical design of the ESPRESSO spectrograph at VLT

ESPRESSO, a very high-resolution, high-efficiency, ultra-high stability, fiber-fed, cross-dispersed echelle spectrograph located in the Combined-Coudé focus of the VLT, has been designed to detect exo-planets with unprecedented radial velocity accuracies of 10 cm/sec over 20 years period. To increase spectral resolution, an innovative pupil slicing technique has been adopted, based onto free-form optics. Anamorphism has been added to increase resolution while keeping the physical size of the echelle grating within reasonable limits. Anamorphic VPH grisms will help to decrease detector size, while maximizing efficiency and inter-order separation. Here we present a summary of the optical design of the spectrograph and of expected performances.

The FEROS-Lick/SDSS observational data base of spectral indices of FGK stars for stellar population studies

ABSTRACT We present FEROS–Lick/SDSS, an empirical database of Lick/SDSS spectral in-dices of FGK stars to be used in population synthesis projects for discriminating dif-ferent stellar populations within the integrated light of galaxies and globular clusters.From about 2500 FEROS stellar spectra obtained from the ESO Science Archive Facil-ity we computed line–strength indices for 1085 non–supergiant stars with atmosphericparameter estimates from the AMBRE project.Two samples of 312 dwarfs and of 83 subgiants with solar chemical compositionand no significant α–element abundance enhancement are used to compare their ob-servational indices with the predictions of the Lick/SDSS library of synthetic indices.In general, the synthetic library reproduces very well the behaviour of observationalindices as a function of temperature, but in the case of low temperature (T eff .5000K)dwarfs; low temperature subgiants are not numerous enough to derive any conclusion.Several possible causes of the disagreement are discussed and promising theoreticalimprovements are presented.Key words: stars: late-type – stars: fundamental parameters – astronomical databases: miscellaneous.

Challenges and peculiarities of ESPRESSO Data Flow Cycle: from target choice to scientific results

Since the beginning of the ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) project, it has been recognized that the expected challenging scientific results can be achieved only if an integrated view of the end-to-end operations is properly tackled. Hunting for rocky exoplanets and/or studying the possible variations of physical constants requires not only a dedicated, state-of-the-art spectrograph in terms of hardware and optics, but also a tailored observation strategy, data reduction pipeline and data analysis tools (ESPRESSO will be the first ESO instrument for which a customized Data Analysis Software will be provided to the community by the Consortium). In this paper we present the planned data flow system (DFS) for ESPRESSO as emerged after the Preliminary Design Review held in November 2011. Main requirements in terms of observation strategy/preparation and data reduction/analysis are analyzed and the corresponding foreseen (conceptual) design, able to fulfill them, discussed. Eventually, peculiarities and challenges needed to adapt ESPRESSO DFS in the pre-existing ESO/VLT DFS framework are outlined.

Performances of X-shooter, the new wide-band intermediate resolution spectrograph at the VLT

X-shooter is the first second-generation instrument newly commissioned a the VLT. It is a high efficiency single target intermediate resolution spectrograph covering the range 300 - 2500 nm in a single shot. We summarize the main characteristics of the instrument and present its performances as measured during commissioning and the first months of science operations.

EVALSO: enabling virtual access to Latin American southern observatories

In the field of observational astrophysics, the remoteness of the facilities and the ever increasing data volumes and detectors poses new technological challenges. As an example, the VISTA and VST wide field telescopes, which are being constructed at the ESOs Cerro Paranal Observatory and will be ready in the next few years, have cameras which will produce after just one year of operation a volume of data that will exceed all the data collected by the VLT since the start of operations in 1999. This sets serious limitations if such large quantities of data must be transferred and accessed in a short time by the participating European Institutions. The EVALSO project, approved by the European Community, addresses these targets in two major ways. It will create a physical infrastructure to efficiently connect these facilities to Europe. This infrastructure will be complementary to the international infrastructure already created in the last years with the EC support (RedCLARA, ALICE, GEANT). Besides this, it will provide the astronomers with Virtual Presence (VP), i.e. the tools to perform and control an astronomical observation from the users site. The main role of INAF - Astronomical Observatory of Trieste (OAT) within the project will be the definition of the architecture, the development of VP system and the integration of a prototype to be used as a demonstrator. This paper will focus on the description of the Virtual Presence system.