ARES v2 - new features and improved performance

Aims: We present a new upgraded version of ARES. The new version includes a series of interesting new features such as automatic radial velocity correction, a fully automatic continuum determination, and an estimation of the errors for the equivalent widths. Methods: The automatic correction of the radial velocity is achieved with a simple cross-correlation function, and the automatic continuum determination, as well as the estimation of the errors, relies on a new approach to evaluating the spectral noise at the continuum level. Results: ARES v2 is totally compatible with its predecessor. We show that the fully automatic continuum determination is consistent with the previous methods applied for this task. It also presents a significant improvement on its performance thanks to the implementation of a parallel computation using the OpenMP library.Comment: 4 pages, 2 Figures; accepted in A&A; ARES Webpage: www.astro.up.pt/~sousasag/are

About the file room by antoni muntadas: a pioneering example of cyber-artivism

En este trabajo se proponen una serie de reflexiones en torno al concepto de «ciberartivismo» tomando como objeto de estudio el proyecto The File Room (1994-) del artista Antoni Muntadas. A partir de un análisis formal y técnico de este en su contexto se aborda la redefinición ontológica de la obra de arte contemporánea, cuyo mecanismo adelanta en varios sentidos la naturaleza de las nuevas formas de subversión política desarrolladas en Internet.In this paper a set of reflections on the concept of «cyber-artivism» is proposed, taking as a case study the project The File Room (1994) by the artist Antoni Muntadas. From a formal and technical analysis of this in its context, an ontological redefinition of the contemporary work of art, whose mechanism advances in several ways the new forms of political subversion developed in Internet, is approached

Vibratory Neurostimulator for Patients with Essential Tremor

The present research shows a prototype that seeks the suppression of essential tremor in a neuroprosthesis that emits vibrations to saturate the channels of communication of this pathology, initially presents a general concept of the disease, and the treatments that seek to correct this symptom known as tremor. It was essential to follow the general outlines of the design and development of the device, and subsequently the results obtained and conclusions that validate the hypotheses raised, the authors propose a series of works that validate the system and the hypotheses itself. &nbsp

Chemical abundances of 1111 FGK stars from the HARPS-GTO planet search sample. III. Sulfur

Context. Elemental abundances are of prime importance to help us reconstruct the origin and evolution of stars and galaxies in our Universe. Sulfur abundances have not been as heavily studied as other elements, so some details regarding its behaviour are still unclear. Aims. We aim to investigate [S/Fe] ratios in stars of the solar neighbourhood in order to analyse the chemical evolution of sulfur and probe for possible differences in abundances of planet host and non-planet host stars. Methods. We use the code MOOG to perform spectral synthesis and derive v*sin(i) values and [S/Fe] ratios for 719 FGK stars with high-resolution (R~115000) and high-quality spectra from the HARPS-GTO program. We find the best fit and corresponding parameter values by performing chi-square minimisation of the deviation between synthetic profiles and observational spectra. Results. Our results reveal that sulfur behaves as a typical alpha-element, with low abundances in young thin disk stars and high abundances in old thick disk stars, following what was expected from our understanding of the Galactic chemical evolution (GCE). Nevertheless, further studies into the abundances of sulfur in very metal-poor stars are required as our sample only derived sulfur abundances to stars with metallicity as low as [Fe/H]=-1.13 dex. High-alpha metal rich stars are more enhanced in sulfur compared to their thin disk counterparts at the same metallicity. We compare our results to GCE models from other authors in the [S/Fe] vs. [Fe/H] plane. The [S/Fe]-age relationship is a good proxy for time, just like it is the case with other alpha-elements. We report no differences in the abundances of sulfur between stars with and without planetary companions in the metallicity range [Fe/H] >= -0.3 dex.Comment: 11 pages, 10 figures. Paper has been accepted for publication in Astronomy & Astrophysic

NIR spectroscopy of the Sun and HD20010 - Compiling a new linelist in the NIR

Context: Effective temperature, surface gravity, and metallicity are basic spectroscopic stellar parameters necessary to characterize a star or a planetary system. Reliable atmospheric parameters for FGK stars have been obtained mostly from methods that relay on high resolution and high signal-to-noise optical spectroscopy. The advent of a new generation of high resolution near-IR spectrographs opens the possibility of using classic spectroscopic methods with high resolution and high signal-to-noise in the NIR spectral window. Aims: We aim to compile a new iron line list in the NIR from a solar spectrum to derive precise stellar atmospheric parameters, comparable to the ones already obtained from high resolution optical spectra. The spectral range covers 10 000 {\AA} to 25 000 {\AA}, which is equivalent to the Y, J, H, and K bands. Methods: Our spectroscopic analysis is based on the iron excitation and ionization balance done in LTE. We use a high resolution and high signal-to-noise ratio spectrum of the Sun from the Kitt Peak telescope as a starting point to compile the iron line list. The oscillator strengths (log gf) of the iron lines were calibrated for the Sun. The abundance analysis was done using the MOOG code after measuring equivalent widths of 357 solar iron lines. Results: We successfully derived stellar atmospheric parameters for the Sun. Furthermore, we analysed HD20010, a F8IV star, from which we derived stellar atmospheric parameters using the same line list as for the Sun. The spectrum was obtained from the CRIRES- POP database. The results are compatible with the ones found in the literature, confirming the reliability of our line list. However, due to the quality of the data we obtain large errors.Comment: 9 pages and 9 figure

Searching for solar siblings among the HARPS data

The search for the solar siblings has been particularly fruitful in the last few years. Until now, there are four plausible candidates pointed out in the literature: HIP21158, HIP87382, HIP47399, and HIP92831. In this study we conduct a search for solar siblings among the HARPS high-resolution FGK dwarfs sample, which includes precise chemical abundances and kinematics for 1111 stars. Using a new approach based on chemical abundance trends with the condensation temperature, kinematics, and ages we found one (additional) potential solar sibling candidate: HIP97507.Comment: 4 pages, 2 figures, 1 table. Accepted in A&

Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program II: Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu

To understand the formation and evolution of the different stellar populations within our Galaxy it is essential to combine detailed kinematical and chemical information for large samples of stars. We derive chemical abundances of Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu for a large sample of more than 1000 FGK dwarf stars with high-resolution ($R \sim$\,115000) and high-quality spectra from the HARPS-GTO program. The abundances are derived by a standard Local Thermodinamyc Equilibrium (LTE) analysis using measured Equivalent Widths (EWs) injected to the code MOOG and a grid of Kurucz ATLAS9 atmospheres. We find that thick disk stars are chemically disjunct for Zn and Eu and also show on average higher Zr but lower Ba and Y when compared to the thin disk stars. We also discovered that the previously identified high-$\alpha$ metal-rich population is also enhanced in Cu, Zn, Nd and Eu with respect to the thin disk but presents Ba and Y abundances lower on average, following the trend of thick disk stars towards higher metallities and further supporting the different chemical composition of this population. The ratio of heavy-s to light-s elements of thin disk stars presents the expected behaviour (increasing towards lower metallicities) and can be explained by a major contribution of low-mass AGB stars for s-process production at disk metallicities. However, the opposite trend found for thick disk stars suggests that intermediate-mass AGB stars played an important role in the enrichment of the gas from where these stars formed. Previous works in the literature also point to a possible primary production of light-s elements at low metallicities to explain this trend. Finally, we also find an enhancement of light-s elements in the thin disk at super solar metallicities which could be caused by the contribution of metal-rich AGB stars. (short version)Comment: 20 pages, 19 figures, accepted by A&