A5010555358- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Planetary Science and Exploration
- Solar and Space Plasma Dynamics
- CCD and CMOS Imaging Sensors
- Adaptive optics and wavefront sensing
- Geomagnetism and Paleomagnetism Studies
- Astronomical and nuclear sciences
- Phase-change materials and chalcogenides
- Photocathodes and Microchannel Plates
- Chemical Thermodynamics and Molecular Structure
- Spectroscopy and Laser Applications
- Electrical and Electromagnetic Research
- Space Exploration and Technology
- History and Developments in Astronomy
- Atmospheric Ozone and Climate
- Geology and Paleoclimatology Research
- Spectroscopy Techniques in Biomedical and Chemical Research
- Gas Sensing Nanomaterials and Sensors
- Magnesium Alloys: Properties and Applications
National Institute for Space Research
2011-2023
University of Central Lancashire
2009
Universidade de São Paulo
1997
Museu de Astronomia e Ciências Afins
1992
We present results derived from the first multi-chord stellar occultations by transneptunian object (50000) Quaoar, observed on 2011 May 4 and 2012 February 17, a single-chord occultation October 15. If timing of five chords obtained in were correct, then Quaoar would possess topographic features (crater or mountain) that be too large for body this mass. An alternative model consists applying time shifts to some account possible errors. Satisfactory elliptical fits are possible, yielding an...
We have analyzed high-resolution and high signal-to-noise ratio optical spectra of nearby FGK stars with without detected giant planets in order to homogeneously measure their photospheric parameters, mass, age, the abundances volatile (C, N, O) refractory (Na, Mg, Si, Ca, Ti, V, Mn, Fe, Ni, Cu, Ba) elements. Our sample contains 309 from solar neighborhood (up distance 100 pc), out which 140 are dwarfs, 29 subgiants, giants. The parameters derived equivalent widths Fe I II lines. Masses ages...
We present a determination of photospheric parameters and C abundances for sample 172 G K dwarfs, subgiants, giants with without detected planets in the solar neighbourhood. The analysis was based on high S/N resolution spectra observed ELODIE spectrograph, which observational data publicly available. intend to contribute precise homogeneous studies that compare behaviour light elements stars, hosting or not. This will bring new arguments discussion possible anomalies have been suggested...
We report the abundances of C, Na, Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Sm in 25 solar-type stars solar neighbourhood, their correlations with ages, kinematics, orbital parameters. The spectroscopic analysis, based high resolution S/N ratio data, was differential to Sun applied atomic line EWs C C2 spectral synthesis. performed a statistical study using tree clustering searching for groups sharing similar abundance patterns. derived Teff, log(g),...
We have obtained [Mg/Fe] measurements for 76.3% of the stars in MILES spectral library used understanding stellar atmospheres and populations galaxies star clusters. These abundance ratios were through (1) a compilation values from literature using abundances high-resolution spectroscopic studies (2) robust analysis mid-resolution optical spectra. All carefully calibrated to single uniform scale, by an extensive control sample with results The small average uncertainties (respectively 0.09...
The Na I near-infrared feature has been used to indicate the dwarf/giant population in composite systems, but its interpretation is still an issue of contention. In order try understand behavior this controversial feature, we study spectra cool stars by means both observed and synthetic spectra.
We have investigated the thorium (Th) abundance in a sample of 53 thin disc solar twins covering wide range ages. These data provide constrains on mantle energy budget terrestrial planets that can be formed over evolution Galaxy's disc. estimated Th abundances with an average precision 0.025\,dex (in both [Th/H] and [Th/Fe]) through comprehensive spectral synthesis Th\,II line present at 4019.1290\,{\AA}, using very high resolution (R\,=\,115,000) quality HARPS spectra obtained ESO La Silla...
Abundances of light elements in dwarf stars different ages are important constraints for stellar yields, Galactic chemical evolution and exoplanet composition studies. We have measured C N abundances $^{12}$C/$^{13}$C ratios a sample 63 solar twins spanning wide range age, based on spectral synthesis comprehensive list CH\,A-X CN\,B-X features using HARPS spectra. The analysis 55 thin disc confirms the dependences [C/Fe] [N/Fe] [Fe/H]. is investigated as function [Fe/H] age first time these...
To analyse stellar populations in galaxies a widely used method is to apply theoretically derived responses of spectra and line indices element abundance variations, hereafter referred as response functions. These are applied differential way, base models, order generate or with different patterns. In this paper sets such functions for three evolutionary stages tested new empirical [Mg/Fe] data the MILES spectral library. Recent theoretical models observations investigate effects [Fe/H],...
We present results from three world-wide campaigns that resulted in the detections of two single-chord and one multi-chord stellar occultations by plutino object (84922) 2003 VS2. From 2013 2014 we obtained accurate astrometric positions for object, while occultation on November 7, parameters best-fitting ellipse to limb body at time occultation. also short-term photometry data order derive its rotational phase during The light curve a peak-to-peak amplitude 0.141 ± 0.009 mag. This allows us...
We report the results of two multi-chord stellar occultations by dwarf planet (1) Ceres that were observed from Brazil on 2010 August 17, and USA 2013 October 25. Four positive detections obtained for occultation, nine occultation. Elliptical models adjusted to chords obtain Ceres' size shape. Two limb fitting solutions studied each event. The first one is a nominal solution with an indeterminate polar aspect angle. second was constrained pole coordinates as given Drummond et al. Assuming...
Context.Understanding how each early-type galaxy forms and evolves is one of the objectives extragalactic astrophysics cosmology. The spatial distribution stellar populations inside a spheroidal system their kinematic properties supply important information about formation process. reconstruction star history crucial in this context.
In order to derive the ratio of α-elements iron in galaxies, we have observed strongest TiO band heads γ and γ' systems at 7000–7500 Å a sample dozen early-type galaxies. The equivalent widths bands are compared with synthetic spectra for single-aged stellar populations composite galaxy models, all computed [α/Fe] = 0.0 +0.3. same method is also applied ⟨Fe⟩ Mg2 Lick indices results obtained [Ti/Fe] ≈ [Mg/Fe] +0.3, indicating clear enhancement α-elements–to–iron our
We present a summary of the concept design report new astronomical instrument: SPARC4, Simultaneous Polarimeter and Rapid Camera in 4 bands. SPARC4 will provide photometry polarimetry four optical broad bands (griz SDSS) simultaneously. This is achieved by use dichroic beam splitters. The square eld view around 5.6 arcmin on side. time resolution sub-second for somewhat longer polarimetry. provided fast EMCCDs. main motivation building to explore astrophysical objects which exhibit temporal...
ABSTRACT Astrometric studies and orbital modelling of planetary moons have contributed significantly to advancing our understanding their dynamics. These require precise positions measured over extended periods. In this paper, we present the results 2021 Brazilian Jovian mutual phenomena campaign. The data correspond eight events between Galilean satellites, in addition a rare eclipse Thebe, an inner satellite, totalling nine events. A geometric model along with DE440/JUP365 ephemerides was...
ABSTRACT Extragalactic astronomy and stellar astrophysics are intrinsically related. In fact, the determination of important galaxy properties such as masses, star formation histories, or chemical abundances relies on ability to model their populations. One ingredient these models is libraries. Empirical libraries must have a good coverage Teff, [Z/H], surface gravity, parameters reliably determined. MILES one most widely used empirical Here, we present an extension this library with 205 new...
We investigate the interaction effects in stellar and gas kinematics, population ionized properties interacting galaxy pair AM1209-292, composed by NGC4105 NGC4106. The data consist of long-slit spectra range 3000-7050 {\AA}. massive E3 presents a flat velocity profile, while is strong rotation, suggesting external origin. Its companion, NGC4106, shows asymmetries radial field, likely due to interaction. dynamics was modeled using P-Gadget3 TreePM/SPH code, from which we show that system has...
We present the basic concept of a new astronomical instrument: SPARC4 - Simultaneous Polarimeter and Rapid Camera in 4 bands. combines one (i) photometric polarimetric modes; (ii) sub-second time-resolution mode excellent timeresolution mode; (iii) simultaneous imaging four broad-bands for both modes. This combination will make unique facility ground-based optical observatories. Presently, project is its conceptual design phase.