Marcello Lodi

Harps-N: the new planet hunter at TNG

The Telescopio Nazionale Galileo (TNG)[9] hosts, starting in April 2012, the visible spectrograph HARPS-N. It is based on the design of its predecessor working at ESOs 3.6m telescope, achieving unprecedented results on radial velocity measurements of extrasolar planetary systems. The spectrographs ultra-stable environment, in a temperature-controlled vacuum chamber, will allow measurements under 1 m/s which will enable the characterization of rocky, Earth-like planets. Enhancements from the original HARPS include better scrambling using octagonal section fibers with a shorter length, as well as a native tip-tilt system to increase image sharpness, and an integrated pipeline providing a complete set of parameters. Observations in the Kepler field will be the main goal of HARPS-N, and a substantial fraction of TNG observing time will be devoted to this follow-up. The operation process of the observatory has been updated, from scheduling constraints to telescope control system. Here we describe the entire instrument, along with the results from the first technical commissioning.

HARPS-N OBSERVES THE SUN AS A STAR

Radial velocity perturbations induced by stellar surface inhomogeneities including spots, plages and granules currently limit the detection of Earth-twins using Doppler spectroscopy. Such stellar noise is poorly understood for stars other than the Sun because their surface is unresolved. In particular, the effects of stellar surface inhomogeneities on observed stellar radial velocities are extremely difficult to characterize, and thus developing optimal correction techniques to extract true stellar radial velocities is extremely challenging. In this paper, we present preliminary results of a solar telescope built to feed full-disk sunlight into the HARPS-N spectrograph, which is in turn calibrated with an astro-comb. This setup enables long-term observation of the Sun as a star with state-of-the-art sensitivity to radial velocity changes. Over seven days of observing in 2014, we show an average 50\cms radial velocity rms over a few hours of observation. After correcting observed radial velocities for spot and plage perturbations using full-disk photometry of the Sun, we lower by a factor of two the weekly radial velocity rms to 60\cms. The solar telescope is now entering routine operation, and will observe the Sun every clear day for several hours. We will use these radial velocities combined with data from solar satellites to improve our understanding of stellar noise and develop optimal correction methods. If successful, these new methods should enable the detection of Venus over the next two to three years, thus demonstrating the possibility of detecting Earth-twins around other solar-like stars using the radial velocity technique.

GIANO-TNG spectroscopy of red supergiants in the young star cluster RSGC2

Aims. The inner disk of the Galaxy has a number of young star clusters dominated by red supergiants that are heavily obscured by dust extinction and observable only at infrared wavelengths. These clusters are important tracers of the recent star formation and chemical enrichment history in the inner Galaxy. Methods. During the technical commissioning and as a first science verification of the GIANO spectrograph at the Telescopio Nazionale Galileo, we secured high-resolution (R � 50 000) near-infrared spectra of three red supergiants in the young Scutum cluster RSGC2. Results. Taking advantage of the full YJHK spectral coverage of GIANO in a single exposure, we were able to identify several tens of atomic and molecular lines suitable for chemical abundance determinations. By means of spectral synthesis and line equivalent width measurements, we obtained abundances of Fe and other iron-peak elements such as V, Cr, Ni, of alpha (O, Mg, Si, Ca and Ti) and other light elements (C, N, Na, Al, K, Sc), and of some s-process elements (Y, Sr). We found iron abundances between half and one third solar and solar-scaled [X/Fe] abundance patterns of iron-peak, alpha and most of the light elements, consistent with a thin-disk chemistry. We found a depletion of [C/Fe] and enhancement of [N/Fe], consistent with CN burning, and low 12 C/ 13 C abundance ratios (between 9 and 11), requiring extra-mixing processes in the stellar interiors during the post-main-sequence evolution. Finally, we found a slight [Sr/Fe] enhancement and a slight [Y/Fe] depletion (by a factor of ≤2), with respect to solar.

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.

Lines and continuum sky emission in the near infrared: observational constraints from deep high spectral resolution spectra with GIANO-TNG

Aims. Determining the intensity of lines and continuum airglow emission in the H-band is important for the design of faint-object infrared spectrographs. Existing spectra at low or medium resolution cannot disentangle the true sky continuum from instrumental effects (e.g. diffuse light in the wings of strong lines). We aim to obtain, for the first time, a high-resolution infrared spectrum that is deep enough to set significant constraints on the continuum emission between the lines in the H-band. Methods. During the second commissioning run of the GIANO high-resolution infrared spectrograph at La Palma Observatory, we pointed the instrument directly at the sky and obtained a deep spectrum that extends from 0.97 to 2.4 μm. Results. The spectrum shows about 1500 emission lines, a factor of two more than in previous works. Of these, 80% are identified as OH transitions; half of these are from highly excited molecules (hot-OH component) that are not included in the OH airglow emission models normally used for astronomical applications. The other lines are attributable to O2 or unidentified. Several of the faint lines are in spectral regions that were previously believed to be free of line emission. The continuum in the H-band is marginally detected at a level of about 300 photons/m2/s/arcsec2/μm, equivalent to 20.1 AB-mag/arcsec2. The observed spectrum and the list of observed sky lines are published at the CDS. Conclusions. Our measurements indicate that the sky continuum in the H-band could be even darker than previously believed. However, the myriad of airglow emission lines severely limits the spectral ranges where very low background can be effectively achieved with lowor medium-resolution spectrographs. We identify a few spectral bands that could still remain quite dark at the resolving power foreseen for VLT-MOONS (R 6600).

A GIANO-TNG high-resolution infrared spectrum of the airglow emission

Aims. A flux-calibrated high-resolution spectrum of the airglow emission is a practical λ-calibration reference for astronomical spectral observations. It is also useful for constraining the molecular parameters of the OH molecule and the physical conditions in the upper mesosphere. Methods. We used the data collected during the first technical commissioning of the GIANO spectrograph at the Telescopio Nazionale Galileo (TNG). The high-resolution (R � 50 000) spectrum simultaneously covers the 0.95–2.4 μm wavelength range. Relative flux calibration is achieved by the simultaneous observation of a spectrophotometric standard star. Results. We derived a list of improved positions and intensities of OH infrared lines. The list includes Λ-split doublets, many of which are spectrally resolved. Compared with previous works, the new results correct errors in the wavelengths of the Q-branch transitions. The relative fluxes of OH lines from different vibrational bands show remarkable deviations from theoretical predictions: the Δv = 3, 4 lines are a factor of 2 and 4 brighter than expected. We also found evidence of a significant fraction (1–4%) of OH molecules with a non-thermal population of high-J levels. Finally, we list wavelengths and fluxes of 153 lines not attributable to OH. Most of these can be associated with O2, while 37 lines in the H band are not identified. The O2 and unidentified lines in the H band account for � 5% of the total airglow flux in this band.

Final design and progress of WEAVE: the next generation wide-field spectroscopy facility for the William Herschel Telescope

We present the Final Design of the WEAVE next-generation spectroscopy facility for the William Herschel Telescope (WHT), together with a status update on the details of manufacturing, integration and the overall project schedule now that all the major fabrication contracts are in place. We also present a summary of the current planning behind the 5-year initial phase of survey operations. WEAVE will provide optical ground-based follow up of ground-based (LOFAR) and space-based (Gaia) surveys. WEAVE is a multi-object and multi-IFU facility utilizing a new 2-degree prime focus field of view at the WHT, with a buffered pick-and-place positioner system hosting 1000 multi-object (MOS) fibres, 20 integral field units, or a single large IFU for each observation. The fibres are fed to a single (dual-beam) spectrograph, with total of 16k spectral pixels, located within the WHT GHRIL enclosure on the telescope Nasmyth platform, supporting observations at R~5000 over the full 370-1000nm wavelength range in a single exposure, or a high resolution mode with limited coverage in each arm at R~20000. The project is now in the manufacturing and integration phase with first light expected for early of 2018.

High resolution near IR spectroscopy with GIANO-TNG

GIANO is the high resolution near IR spectrograph recently commissioned at the 3.58m Telescopio Nazionale Galileo in La Palma (Spain). GIANO is the first worldwide instrument providing cross-dispersed echelle spectroscopy at a resolution of 50,000 over the 0.95 – 2.45 micron spectral range in a single exposure. There are outstanding science cases in the research fields of exo-planets, Galactic stars and stellar populations that could strongly benefit from GIANO observations down to a magnitude limit comparable to that of 2MASS. The instrument includes a fully cryogenic spectrograph and an innovative fiber system transmitting out to the K band. It also represents a formidable laboratory to test performances and prototype solutions for the next generation of high resolution near IR spectrographs at the ELTs. First results from sky tests at the telescope and science verification occurred between July 2012 and October 2013 will be presented.

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

GIARPS@TNG: GIANO-B and HARPS-N together for a wider wavelength range spectroscopy

Abstract.Since 2012, thanks to the installation of the high-resolution echelle spectrograph in the optical range HARPS-N, the Italian telescope TNG (La Palma) became one of the key facilities for the study of the extrasolar planets. In 2014 TNG also offered GIANO to the scientific community, providing a near-infrared (NIR) cross-dispersed echelle spectroscopy covering 0.97-2.45μm at a resolution of 50000. GIANO, although designed for direct light-feed from the telescope at the Nasmyth-B focus, was provisionally mounted on the rotating building and connected via fibers to only available interface at the Nasmyth-A focal plane. The synergy between these two instruments is particularly appealing for a wide range of science cases, especially for the search of exoplanets around young and active stars and the characterisation of their atmosphere. Through the funding scheme “WOW” (a Way to Others Worlds), the Italian National Institute for Astrophysics (INAF) proposed to position GIANO at the focal station for which it was originally designed and the simultaneous use of these spectrographs with the aim to achieve high-resolution spectroscopy in a wide wavelength range (0.383-2.45μm) obtained in a single exposure, giving rise to the project called GIARPS (GIANO-B & HARPS-N). Because of its characteristics, GIARPS can be considered the first and unique worldwide instrument providing not only high resolution in a large wavelength band, but also a high-precision radial velocity measurement both in the visible and in the NIR arm, since in the next future GIANO-B will be equipped with gas absorption cells.