E. Rossetti

Chemical abundance analysis of the open clusters Cr 110, NGC 2099 (M 37), NGC 2420, NGC 7789, and M 67 (NGC 2682)

Context. The present number of Galactic open clusters that have high resolution abundance determinations, not only of [Fe/H], but also of other key elements, is largely insufficient to enable a clear modeling of the Galactic disk chemical evolution. Aims. To increase the number of Galactic open clusters with high quality measurements. Methods. We obtained high resolution (R ∼ 30 000), high quality (S /N ∼ 50–100 per pixel), echelle spectra with the fiber spectrograph FOCES, at Calar Alto, Spain, for three red clump stars in each of five Open Clusters. We used the classical equivalent width analysis method to obtain accurate abundances of sixteen elements: Al, Ba, Ca, Co, Cr, Fe, La, Mg, Na, Nd, Ni, Sc, Si, Ti, V, and Y. We also derived the oxygen abundance using spectral synthesis of the 6300 A forbidden line. Results. Three of the clusters were never studied previously with high resolution spectroscopy: we found [Fe/H] =+ 0.03 ± 0.02 (±0.10) dex for Cr 110; [Fe/H] =+ 0.01 ± 0.05 (±0.10) dex for NGC 2099 (M 37), and [Fe/H] = −0.05 ± 0.03 (±0.10) dex for NGC 2420. This last finding is higher than typical literature estimates by 0.2–0.3 dex approximately and in closer agreement with Galactic trends. For the remaining clusters, we find that [Fe/H] =+ 0.05 ± 0.02 (±0.10) dex for M 67 and [Fe/H] =+ 0.04 ± 0.07 (±0.10) dex for NGC 7789. Accurate (to ∼0.5 km s −1 ) radial velocities were measured for all targets, and we provide the first velocity estimate derived from high resolution data for Cr 110, � Vr� = 41.0 ± 3. 8k m s −1 . Conclusions. With our analysis of the new clusters Cr 110, NGC 2099, and NGC 2420, we increase the sample of clusters with highresolution-based abundances by 5%. All our program stars show abundance patterns which are typical of open clusters, very close to solar with few exceptions. This is true for all the iron-peak and s-process elements considered, and no significant α-enhancement is found. No significant (anti-)correlations for Na, Al, Mg, and O abundances are found. If anticorrelations are present, the involved spreads must be <0.2 dex. We then compile high resolution data of 57 OC from the literature and find a gradient of [Fe/H] with Galactocentric radius of –0.06 ± 0.02 dex kpc −1 , in agreement with past work and with results for Cepheids and B stars in the same range. A change of slope is seen outside RGC = 12 kpc and [α/Fe] shows a tendency to increase with RGC. We also confirm the absence of a significant age-metallicity relation, finding slopes of –2.6 ± 1.1 × 10 −11 dex Gyr −1 and 1.1 ± 5.0 × 10 −11 dex Gyr −1 for [Fe/H] and [α/Fe] respectively.

Mass motions and chromospheres of RGB stars in the globular cluster NGC 2808

We present the results of the first observations, taken with FLAMES during Science Verification, of red giant branch (RGB) stars in the globular cluster NGC 2808. A total of 137 stars was observed, of which 20 at high resolution (R = 47 000) with UVES and the others at lower resolution (R = 19 000-29 000) with GIRAFFE in MEDUSA mode, monitoring ∼3 mag down from the RGB tip. Spectra were taken of the Ha, Na I D and Ca II H and K lines. This is by far the largest and most complete collection of such data in globular cluster giants, both for the number of stars observed within one cluster, and for monitoring all the most important optical diagnostics of chromospheric activity/mass motions. Evidence of mass motions in the atmospheres was searched from asymmetry in the profiles and coreshifts of the Ha, Na I D and Ca II K lines, as well as from Ha emission wings. We have set the detection thresholds for the onset of Ha emission, negative Na D 2 coreshifts and negative K 3 coreshifts at log L/L ○. ∼ 2.5, 2.9 and 2.8, respectively. These limits are significantly fainter than the results found by nearly all previous studies. Also the fraction of stars where these features have been detected has been increased significantly with respect to the previous studies. Our observations confirm the widespread presence of chromospheres among globular cluster giants, as it was found among Population I red giants. Some of the above diagnostics suggest clearly the presence of outward mass motions in the atmosphere of several stars.

The GIANO spectrometer: towards its first light at the TNG

GIANO is a high resolution (R50,000) IR spectrograph which provides a quasi-complete coverage of the 0.95- 2.5μm wavelengths range in a single exposure. The instrument was integrated and tested in Arcetri-INAF (Florence, Italy) and will be commisioned at the 3.58m TNG Italian telescope in La Palma. The major scientific goals include the search for rocky planets with habitable conditions around low-mass stars, quantitative spectroscopy of brown dwarfs, accurate chemical abundances of high metallicity stars and stellar clusters. This presentation describes the status of the instrument and presents the first results obtained in laboratory during the acceptance tests.

The GIANO-TNG spectrometer

GIANO is an infrared (0.9-2.5 μm cross-dispersed echelle spectrometer designed to achieve high resolution, high throughput, wide band coverage and very high stability for accurate radial velocity measurements. It also includes polarimetric capabilities and a low resolution mode with RS ~ 400 and complete 0.75-2.5 μm coverage. This makes it a very versatile, common user instrument which will be permanently mounted and available on the Nasmyth-B foci of the Telescopio Nazionale Galileo (TNG) located at Roque de Los Muchachos Observatory (ORM), La Palma, Spain. The project is fast-track and relies on well known, relatively standard technologies. It has been recognized as one of the top priority instrumental projects of INAF (the Italian National Institute of Astronomy) and received its first financing for the phase-A study in October 2003. Integration in the laboratory is planned to start before the end of 2006, commissioning at the telescope is foreseen within 2007 and scientific operations in 2008. One of the most important scientific goals is the search for rocky planets with habitable conditions around low-mass stars. If completed on time, GIANO will be the first and only IR instrument operating worldwide providing the combination of efficiency, spectral resolution, wavelength coverage and stability necessary for this type of research. With its unique combination of high and low resolution modes, GIANO will also be a very flexible common-user instrument ideal e.g. for quantitative spectroscopy of brown dwarfs, stars and stellar clusters as well as for the determination of the spectral energy distribution of faint/red objects such as high redshift galaxies. The expected limiting magnitudes are such that GIANO will be able to deliver good quality HR spectra of any 2MASS object and LR spectra of any object detected in the UKIDSS large area survey.

GIANO: an ultrastable IR echelle spectrometer optimized for high-precision radial velocity measurements and for high-throughput low-resolution spectroscopy

GIANO is an infrared (0.9-2.5 μm) cross-dispersed echelle spectrometer designed to achieve high throughput, high resolving power, wide band coverage and high accuracy radial velocity measurements. It also includes polarimetric capabilities and a low resolution mode that make it a very versatile, common user instrument which will be permanently mounted and available at one of the Nasmyth foci of the Telescopio Nazionale Galileo (TNG) located at Roque de Los Muchachos Observatory (ORM), La Palma, Spain. GIANO was selected by INAF as the top priority instrument among those proposed within the Second Generation Instrumentation Plan of the TNG. More information on this project can be found at the web page http://www.bo.astro.it/giano

GIANO: software design and acquisition facilities

We present the general software design and acquisition facilities of GIANO, an ultra-stable IR echelle spectrometer optimized both for low (R ≃ 500) and high (R ≃ 50, 000) resolution, that will be mounted at Nasmyth-B focus of the Telescopio Nazionale Galileo (TNG). We describe the high-level software structure of the instrument, the user interface characteristics and the control of all subsystems. The management of GIANO sensors and controls of the mechanical movements is indeed a crucial issue that is handled by dedicated tasks. Monitoring of all these parameters is performed by means of separated processes running in background on the control workstation (PC). In this paper we will also schematically discuss the software for the instrument control, status display and setup, the quick look facility and the pipeline for data reduction.

The versatile acquisition system of Giano

Giano is an infrared (0.9-2.5 μm) cross-dispersed echelle spectrometer designed to achieve high throughput, high resolving power, wide band coverage and high accuracy. Giano will be a common user instrument which will be permanently mounted at the Telescopio Nazionale Galileo (TNG), located at Roque de Los Muchachos Observatory (ORM), La Palma, Spain. Giano successfully concluded the development phase, and we present here some of the solutions adopted in the focal plane electronics, which take care of detector control and data acquisition and handling.

Performances of the cryogenic system of GIANO-TNG

GIANO-TNG is a cryogenic high resolution infrared spectrometer whose optics include large aspheric mirrors and cross-dispersing prisms mounted over a ≃1.5 m2 aluminum bench. To achieve the highest possible spectral stability and repeatability the bench is internally filled with liquid nitrogen whose boil-off pressure is actively controlled and stabilized to a fraction of mbar. The bench is isostatically mounted inside a ≃2.5 m3 cryostat. We present the characteristics and performances of the cryogenic system of GIANO which include, in particular, a temperature uniformity and long-term stability of a few mK and a remarkably low consumption of liquid nitrogen (less than 1 liter/hr).

TheGaiaspectrophotometric standard stars survey - I. Preliminary results: Gaia SPSS survey - I. Preliminary results

We describe two ground-based observing campaigns aimed at building a grid of approximately 200 spectrophotometric standard stars (SPSS), with an internal ≃1 per cent precision and tied to Vega within ≃3 per cent, for the absolute flux calibration of data gathered by Gaia, the European Space Agency (ESA) astrometric mission. The criteria for the selection and a list of candidates are presented, together with a description of the survey strategy and the adopted data analysis methods. We also discuss a short list of notable rejected SPSS candidates and difficult cases, based on identification problems, literature discordant data, visual companions and variability. In fact, all candidates are also monitored for constancy (within ±5 mmag, approximately). In particular, we report on a CALSPEC standard, 1740346, that we found to be a δ Scuti variable during our short-term monitoring (1-2 h) campaign. Based on data obtained within the Gaia Data Processing and Analysis Consortium (DPAC) - and coordinated by the Ground-based Observations for Gaia (GBOG) working group - at various telescopes; see acknowledgments.

The Gaia spectrophotometric standard stars survey

We describe two ground-based observing campaigns aimed at building a grid of approximately 200 spectrophotometric standard stars (SPSS), with an internal ≃1 per cent precision and tied to Vega within ≃3 per cent, for the absolute flux calibration of data gathered by Gaia, the European Space Agency (ESA) astrometric mission. The criteria for the selection and a list of candidates are presented, together with a description of the survey strategy and the adopted data analysis methods. We also discuss a short list of notable rejected SPSS candidates and difficult cases, based on identification problems, literature discordant data, visual companions and variability. In fact, all candidates are also monitored for constancy (within ±5 mmag, approximately). In particular, we report on a CALSPEC standard, 1740346, that we found to be a δ Scuti variable during our short-term monitoring (1-2 h) campaign. Based on data obtained within the Gaia Data Processing and Analysis Consortium (DPAC) - and coordinated by the Ground-based Observations for Gaia (GBOG) working group - at various telescopes; see acknowledgments.