A5103070912- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Atmospheric Ozone and Climate
- Solar and Space Plasma Dynamics
- Optical Coherence Tomography Applications
- Marine and coastal ecosystems
- Spectroscopy Techniques in Biomedical and Chemical Research
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
- Ancient Mediterranean Archaeology and History
- Optical Polarization and Ellipsometry
- Advanced Optical Sensing Technologies
- Astrophysics and Cosmic Phenomena
- Distributed and Parallel Computing Systems
- Astronomical and nuclear sciences
- Ancient Egypt and Archaeology
- Calibration and Measurement Techniques
- solar cell performance optimization
- Advanced Measurement and Metrology Techniques
Laboratório Nacional de Astrofísica
2009-2024
Ministry of Science, Technology and Innovation
2021-2023
Universidade de São Paulo
1998-2000
Libraries of stellar spectra are fundamental tools for the study populations and both empirical synthetic libraries have been used this purpose. In paper, a new library high resolution is presented, ranging from near-ultraviolet (300nm) to near-infrared (1.8${\rm μ}$m). The spans all types that relevant integrated light old intermediate-age in involved spectral region (spectral F through M luminosity classes). grid was computed metallicities [Fe/H] = --2.5 +0.5, including solar $α$-enhanced...
ABSTRACT This paper presents an overview of SPIRou, the new-generation near-infrared spectropolarimeter/precision velocimeter recently installed on 3.6-m Canada–France–Hawaii Telescope (CFHT). Starting from two main science goals, i.e., quest for planetary systems around nearby M dwarfs and study magnetized star/planet formation, we outline instrument concept that was designed to efficiently address these forefront topics, detail in-lab on-sky performances measured throughout intensive...
view Abstract Citations (153) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Discovery of New Isolated T Tauri Stars de la Reza, Ramiro ; Torres, Carlos A. O. Quast, Germano Castilho, Bruno V. Vieira, Gladys L. Two new stars (TTSs) have been discovered in the neighborhood isolated, strong H-alpha emitting, TTS (CTTS) TW Hya (b = 23 deg). The first object is a visual binary star formed by two CTTSs separated 1.5 arcsec 21 second may be weakly...
Photometric data in the UBV(RI)c system have been acquired for 80 solar analog stars which we previously derived highly precise atmospheric parameters Teff, log g, and [Fe/H] using high resolution, signal-to-noise ratio spectra. UBV (RI)c 46 76 of these stars, respectively, are published first time. Combining our with those from literature, colors system, ~0.01 mag precision, now available 112 analogs. Multiple linear regression is used to derive photometric spectroscopically values. To...
We develop a new set of models for intermediate-metallicity single stellar populations in the blue/optical region and use those to determine spectroscopic age 47 Tuc. The are based on moderately high resolution (1.8 Å, FWHM) empirical spectral library, state-of-the-art theoretical isochrones from M. Salaris most recent Padova group, semiempirical calibrations between fundamental parameters observables. Model line strengths include all corrections deficiencies library that described Paper I....
We perform an empirical synthesis of the blue integrated spectrum metal-rich globular cluster 47 Tucanae, based directly on color-magnitude diagram coupled to a moderately high resolution spectral library. Freed from any significant dependence theory, we are able fundamental test adequacy library and its associated stellar parameters. Excellent fits achieved for almost all absorption-line indices studied, provided computations corrected two limitations library, namely, lack representative...
We have investigated a group of stars known to low chromospheric ages, but high kinematical ages. Isochrone, chemical and lithium ages are estimated for them. The majority in this show abundances much smaller than expected their which is interpreted as an indication old age. Radial velocity measurements the literature also that they not close binaries. results suggest can be formed from coalescence short-period Coalescence rates, calculated taking into account several observational data...
We revisit the abundances of neutron-capture elements in metal-poor ([Fe/H]=-2.9) r-process-rich halo star CS 31082-001. Partly motivated by development new near-ultraviolet Cassegrain U-band Efficient Spectrograph for Very Large Telescope, we compiled an expanded line list heavy over range 3000-4000 {\AA}, including hyperfine structure several elements. Combining archival spectra 31082-001 from Hubble Space Telescope and investigate nucleosynthesis 35 (Ge, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag,...
SPIRou is a near-infrared (nIR) spectropolarimeter / velocimeter proposed as new-generation instrument for CFHT. aims in particular at becoming world-leader on two forefront science topics, (i) the quest habitable Earth-like planets around very- low-mass stars, and (ii) study of star planet formation presence magnetic fields. In addition to these main goals, will be able tackle many key programs, from weather patterns brown dwarf solar-system atmospheres, dynamo processes fully-convective...
Lately, the Italian astronomical community has begun transition to Model Based System Engineering (MBSE). This tool been largely applied development of Cassegrain U-Band Efficient Spectrograph (CUBES) designed provide high instrumental efficiency ( > 37 %) observations in near UV (305-400 nm requirement, 300-420 goal) at a spectral resolving power R 20, 000 (with lower-resolution, skylimited mode ≈ 7, 000). Here, MBSE used mainly 3 areas: requirements management, activities modeling, and...
We present a cautionary study exploring the reliability of Hδ line in integrated spectra galaxies for determining galaxy ages. Our database consists observed ∼120 early-type galaxies, 7 metal-rich globular clusters M31 and Galactic cluster 47 Tuc, open M67. have measured using index definitions designed to assess contamination from CN molecule around by choosing combinations bandpasses that both avoid include region molecular lines redward Hδ. find systematic differences ages derived...
In a previous work we studied the IRAS colours of known Li-rich red giants and showed that they have flux ratios in well defined ranges. By using this result as selection criterion, prepared list 280 Point Source candidates to be giant stars. Up present obtained spectra for our target list. We identified five stars showing strong LiI 670.079 nm line six ones with Li medium strength. Most show features typical normal having circumstellar dust, indicated by their colours.
We present the project of an optical spectrograph equipped with a 1300-element Integral Field Unit (IFU), that will be one main instruments SOAR (4m) telescope. The instrument consists two separate parts, fore-optics and bench spectrograph, are connected by 11 m long fiber bundle. fore optics system is installed at Nasmyth focii telescope, produces image observed object on 26x50 array square microlenses, each 1 mm x lens feeding fiber. fibers have 50 micron cores, aligned entrance to form...
Alongside future observations with the new European Extremely Large Telescope (ELT), optimised instruments on 8-10m generation of telescopes will still be competitive at 'ground UV' wavelengths (3000-4000 A). The near UV provides a wealth unique information nucleosynthesis iron-peak elements, molecules, and neutron-capture elements. In context development near-UV CUBES spectrograph for ESO's Very (VLT), we are investigating impact spectral resolution ability to estimate chemical abundances...
Context. Abundance variations in moderately metal-rich globular clusters can give clues about the formation and chemical enrichment of clusters.
CUBES is a high-efficiency, medium-resolution (R ≃ 20, 000) spectrograph dedicated to the "ground based UV" (approximately wavelength range from 300 400nm) destined for Cassegrain focus of one ESO's VLT unit telescopes in 2018/19. The project joint venture between ESO and Instituto de Astronomia, Geof´ısica e Ciˆencias Atmosf´ericas (IAG) at Universidade S˜ao Paulo Brazilian Laborat´orio Nacional Astrofs´ıca (LNA). will provide access wealth new relevant information stellar as well...
In the era of Extremely Large Telescopes, current generation 8-10m facilities are likely to remain competitive at ground-UV wavelengths for foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed provide high instrumental efficiency ( $>$ 37\%) observations in near UV (305-400 nm requirement, 300-420 goal) a spectral resolving power R 20, 000 (with lower-resolution, sky-limited mode $\sim$ 7, 000). With design focusing on maximizing instrument throughput...
Li abundances are derived for a sample of bulgelike stars with isochronal ages 10-11 Gyr. These have orbits pericentric distances, Rp, as small 2-3 kpc and Zmax < 1 kpc. The comprises G K dwarf in the metallicity range -0.80 4.5 Gyr) within present available. M67 (4.7 NGC 188 (6 oldest studied metal-rich open clusters late-type stars. also been few samples old field In work high dispersion is found all range, comparable values M67. role age on depletion pattern discussed. possible...
Abstract The Total Solar Irradiance (TSI), which is the total radiation arriving at Earth's atmosphere from Sun, one of most important forcing Earths climate. Measurements TSI have been made employing instruments on board several space-based platforms during last four solar cycles. However, combining these measurements still challenging due to degradation sensor elements and long-term stability electronics. Here we describe preliminary efforts design an absolute radiometer based principle...
Protoplanetary nebulae typically present non-spherical envelopes. The origin of such geometry is still controversial. There are indications that it may be carried over from an earlier phase stellar evolution, as the AGB phase. But how early in star's evolution does envelope appear? Li-rich giants show dusty circumstellar envelopes can help answer question. We study a sample fourteen using optical polarimetry order to detect around them. used IAGPOL imaging polarimeter obtain linear...
Abstract In this work, we present temperature, surface gravity, metallicity, microturbulence and element abundances, determined from a detailed spectroscopic analysis for sample of 9 Herbig Ae stars, based on high resolution, S/N spectra.
We present stellar parameters, Li abundances for 21 stars of the young (50 Myears) AB Dor association, based on high-resolution spectra obtained with FEROS at ESO 1.52m telescope, Coudé Spectrograph OPD 1.6m telescope. These results are part an ongoing project determination a large sample T Tauri, post-T Tauri in PMS associations identified Search Associations Containing Young Stars survey. The consists G, K, M counterparts ROSAT bright sources.Since we expect depletion stars, but small G...