Open Cluster Characterization via Cross-Correlation with Spectral Library

We present a characterization method based on spectral cross-correlation to obtain the physical parameters of the controversial stellar aggregate ESO442-SC04. The data used was obtained with GMOS at Gemini-South telescope including 17 stars in the central region of the ob ject and 6 standard-stars. FXCOR was used in an iterative process to obtain self-consistent radial velocities for the standard-stars and averaged radial velocities for the science spectra. Spectral types, effective temperature, suface gravity and metallicities parameters were determined using FXCOR to correlate cluster spectra with ELODIE spectral library and selecting the best correlation matches using the Tonry and Davis Ratio (TDR). Analysis of the results suggests that the stars in ESO442-SC04 are not bound and therefore they do not constitute a physical system.Comment: 4-page paper from IAU symposium 266. Contains 3 eps figures and IAU document class file 'iau.cls

Ultrathin cellulose ester films: preparation, characterization and protein immobilization

In this study cellulose acetate butyrate (CAB) and carboxymehtylcellulose acetate butyrate (CMCAB) films adsorbed onto silicon wafers were characterized by means of ellipsometry, atomic force microscopy (AFM), sum frequency generation spectroscopy (SFG) and contact angle measurements. The adsorption behavior of lysozyme (LIS) or bovine serum albumin (BSA) onto CAB and CMCAB films was investigated. The amounts of adsorbed LIS or BSA onto CMCAB films were more pronounced than those onto CAB films due to the presence of carboxymethyl group in the CMCAB structure. Besides, the adsorption of BSA molecules on CMCAB films was more favored than that of LIS molecules. Antimicrobial effect of LIS bound to CAB or CMCAB layers was evaluated using Micrococcus luteus as substrate.FAPESPCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

Hertz potentials approach to the dynamical Casimir effect in cylindrical cavities of arbitrary section

We study the creation of photons in resonant cylindrical cavities with time dependent length. The physical degrees of freedom of the electromagnetic field are described using Hertz potentials. We describe the general formalism for cavities with arbitrary section. Then we compute explicitly the number of TE and TM motion-induced photons for cylindrical cavities with rectangular and circular sections. We also discuss the creation of TEM photons in non-simply connected cylindrical cavities.Comment: 13 pages, 3 figures, revtex

The Viscacha survey - II: Structure of star clusters in the Magellanic Clouds periphery

We provide a homogeneous set of structural parameters of 83 star clusters located at the periphery of the Small Magellanic Cloud (SMC) and the Large Magellanic Cloud (LMC). The clusters’ stellar density and surface brightness profiles were built from deep, AO assisted optical images, and uniform analysis techniques. The structural parameters were obtained from King and Elson et al. model fittings. Integrated magnitudes and masses (for a subsample) are also provided. The sample contains mostly low surface brightness clusters with distances between 4.5 and 6.5 kpc and between 1 and 6.5 kpc from the LMC and SMC centres, respectively. We analysed their spatial distribution and structural properties, comparing them with those of inner clusters. Half-light and Jacobi radii were estimated, allowing an evaluation of the Roche volume tidal filling. We found that: (i) for both MCs, the tidal radii are on average larger than those of inner clusters; (ii) the core radii dispersion tends to be greater for LMC clusters located towards the southwest, with position angles of ∼200 degrees and about ∼5 degrees from the LMC centre, i.e., those LMC clusters nearer to the SMC; (iii) the analysis of clusters with ages available revealed that the core radius evolution is similar to the one of inner clusters; (iv) Roche volumes are overfilled for SMC clusters with galactocentric distances closer than 3 kpc.Fil: Santos, Joao F. C.. Universidad de La Serena; Chile. Universidade Federal de Minas Gerais; BrasilFil: Maia, Francisco. Universidade Federal do Rio de Janeiro; BrasilFil: Dias, Bruno. Millennium Institute of Astrophysics; Chile. Universidad Andrés Bello; ChileFil: de O. Kerber, Leandro. Universidade Estadual de Santa Cruz; BrasilFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bica, Eduardo. Universidade Federal do Rio Grande do Sul; BrasilFil: Angelo, Mateus S.. Centro Federal de Educacao Tecnológica de Minas Gerais; BrasilFil: Minniti, Dante. Universidad Andrés Bello; Chile. Millennium Institute of Astrophysics; Chile. Vatican Observatory; ItaliaFil: Pérez Villegas, Angeles. Universidade de Sao Paulo; BrasilFil: Roman Lopes, Alexandre. Universidad de La Serena; ChileFil: Westera, Pieter. Universidad Federal Do Abc; BrasilFil: Fraga, Luciano. Laboratorio Nacional de Astrofísica; BrasilFil: Quint, Bruno. Gemini Observatory; ChileFil: Sanmartim, David. Carnegie Institution of Washington; Chil

UVES analysis of red giants in the bulge globular cluster NGC 6522

Context. NGC 6522 is a moderately metal-poor bulge globular cluster ([Fe/H] ~ −1.0), and it is a well-studied representative among a number of moderately metal-poor blue horizontal branch clusters located in the bulge. The NGC 6522 abundance pattern can give hints on the earliest chemical enrichment in the central Galaxy. Aims. The aim of this study is to derive abundances of the light elements C and N; alpha elements O, Mg, Si, Ca, and Ti; odd-Z elements Na and Al; neutron-capture elements Y, Zr, Ba, La, and Nd; and the r-process element Eu. We verify if there are first- and second-generation stars: we find clear evidence of Na–Al, Na–N, and Mg–Al correlations, while we cannot identify the Na–O anti-correlation from our data. Methods. High-resolution spectra of six red giants in the bulge globular cluster NGC 6522 were obtained at the 8m VLT UT2-Kueyen telescope with both the UVES and GIRAFFE spectrographs in FLAMES+UVES configuration. In light of Gaia data, it turned out that two of them are non-members, but these were also analysed. Spectroscopic parameters were derived through the excitation and ionisation equilibrium of Fe I and Fe II lines from UVES spectra. The abundances were obtained with spectrum synthesis. Comparisons of abundances derived from UVES and GIRAFFE spectra were carried out. Results. The present analysis combined with previous UVES results gives a mean radial velocity of vrhel = −15.62±7.7 km s−1 and a metallicity of [Fe/H] = −1.05 ± 0.20 for NGC 6522. Mean abundances of alpha elements for the present four member stars are enhanced with [O/Fe] = +0.38, [Mg/Fe] = ≈+0.28, [Si/Fe] ≈ +0.19, and [Ca/Fe] ≈ +0.13, together with the iron-peak element [Ti/Fe] ≈ +0.13, and the r-process element [Eu/Fe] = +0.40. The neutron-capture elements Y, Zr, Ba, and La show enhancements in the +0.08 < [Y/Fe] < +0.90, 0.11 < [Zr/Fe] < +0.50, 0.00 < [Ba/Fe] < +0.63, 0.00 < [La/Fe] < +0.45, and −0.10 < [Nd/Fe] < +0.70 ranges. We also discuss the spread in heavy-element abundances

The VISCACHA survey - I. Overview and first results

TheVISCACHA (VIsible Soar photometry of star Clusters in tApii and Coxi HuguA) Survey is an ongoing project based on deep photometric observations of Magellanic Cloud star clusters, collected using the SOuthern Astrophysical Research (SOAR) telescope together with the SOAR Adaptive Module Imager. Since 2015 more than 200 h of telescope time were used to observe about 130 stellar clusters, most of them with low mass (M < 104MΘ) and/or located in the outermost regions of the Large Magellanic Cloud and the Small Magellanic Cloud.With this high-quality data set, we homogeneously determine physical properties from statistical analysis of colour-magnitude diagrams, radial density profiles, luminosity functions, and mass functions. Ages, metallicities, reddening, distances, present-day masses, mass function slopes, and structural parameters for these clusters are derived and used as a proxy to investigate the interplay between the environment in theMagellanic Clouds and the evolution of such systems. In this first paper we present the VISCACHA Survey and its initial results, concerning the SMC clusters AM3, K37, HW20, and NGC 796 and the LMC ones KMHK228, OHSC3, SL576, SL61, and SL897, chosen to compose a representative subset of our cluster sample. The project's long-term goals and legacy to the community are also addressed.Fil: Maia, Francisco F. S.. Universidade de Sao Paulo; BrasilFil: Dias, Bruno. Universidad Andrés Bello; Chile. European Southern Observatory Santiago; ChileFil: Santos, Joao F. C.. Universidade Federal de Minas Gerais; BrasilFil: De Kerber, Leandro. Universidade de Sao Paulo; BrasilFil: Bica, Eduardo. Universidade Federal do Rio Grande do Sul; BrasilFil: Piatti, Andres Eduardo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barbuy, Beatriz. Universidade de Sao Paulo; BrasilFil: Quint, Bruno. Gemini Observatory; ChileFil: Fraga, Luciano. Laboratório Nacional de Astrofísica; Brasil. Gemini Observatory; ChileFil: Sanmartim, David. Gemini Observatory; ChileFil: Angelo, Mateus S.. Centro Federal de Educação Tecnológica de Minas Gerais; BrasilFil: Hernandez-Jimenez, Jose A.. Universidade de Sao Paulo; BrasilFil: Santrich, Orlando J. Katime. Universidade Estadual de Santa Cruz; BrasilFil: Oliveira, Raphael A. P.. Universidade de Sao Paulo; BrasilFil: Pérez-Villegas, Angeles. Universidade de Sao Paulo; BrasilFil: Souza, Stefano O.. Universidade de Sao Paulo; BrasilFil: Vieira, Rodrigo G.. Universidade de Sao Paulo; BrasilFil: Westera, Pieter. Universidade Federal do ABC; Brasi

The VISCACHA survey : III. Star clusters counterpart of the Magellanic Bridge and Counter-Bridge in 8D

Context. The interactions between the Small and Large Magellanic Clouds (SMC and LMC) created the Magellanic Bridge; a stream of gas and stars pulled out of the SMC towards the LMC about 150 Myr ago. The tidal counterpart of this structure, which should include a trailing arm, has been predicted by models but no compelling observational evidence has confirmed the Counter-Bridge so far. Aims. The main goal of this work is to find the stellar counterpart of the Magellanic Bridge and Counter-Bridge. We use star clusters in the SMC outskirts as they provide a 6D phase-space vector, age, and metallicity which help characterise the outskirts of the SMC. Methods. Distances, ages, and photometric metallicities were derived from fitting isochrones to the colour-magnitude diagrams from the VISCACHA survey. Radial velocities and spectroscopic metallicities were derived from the spectroscopic follow-up using GMOS in the CaII triplet region. Results. Among the seven clusters analysed in this work, five belong to the Magellanic Bridge, one belongs to the Counter-Bridge, and the other belongs to the transition region. Conclusions. The existence of the tidal counterpart of the Magellanic Bridge is evidenced by star clusters. The stellar component of the Magellanic Bridge and Counter-Bridge are confirmed in the SMC outskirts. These results are an important constraint for models that seek to reconstruct the history of the orbit and interactions between the LMC and SMC as well as constrain their future interaction including with the Milky Way