A5045028978- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Scientific Research and Discoveries
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Adaptive optics and wavefront sensing
- Mechanics and Biomechanics Studies
- Geophysics and Gravity Measurements
- Spacecraft and Cryogenic Technologies
- Spectroscopy and Laser Applications
- Healthcare Regulation
- Impact of Light on Environment and Health
- Calibration and Measurement Techniques
- History and Developments in Astronomy
- Electron Spin Resonance Studies
- CCD and CMOS Imaging Sensors
- Modular Robots and Swarm Intelligence
- Fluid Dynamics Simulations and Interactions
Universidade do Vale do Paraíba
2014-2024
National Council for Scientific and Technological Development
1997-2009
Universidade Federal do Rio Grande do Sul
1997-2007
CEA Paris-Saclay
2001-2004
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2001-2004
Institute of Astronomy and Space Physics
2003
Argentine National Observatory
1999
Consejo Nacional de Investigaciones Científicas y Técnicas
1999
We present K-band imaging observations of ten gamma-ray burst (GRB) host galaxies for which an optical and/or radio afterglow associated with the GRB event was clearly identified.Data were obtained Very Large Telescope and New Technology at ESO (Chile), Gemini-North telescope Mauna Kea (Hawaii).Adding to our sample nine other hosts photometry determined redshifts published in literature, we compare their observed absolute K magnitudes as well R -K colours those distant sources detected...
We show that the black hole in x-ray binary Cygnus X-1 was formed situ and did not receive an energetic trigger from a nearby supernova. The progenitor of had initial mass greater than 40 solar masses, during collapse to form approximately 10-solar X-1, upper limit for could have been suddenly ejected is 1 mass, much less observations suggest high-mass stellar holes may promptly, when massive stars disappear silently.
We examine the relation between oxygen abundances in narrow-line regions (NLRs) of active galactic nuclei (AGNs) estimated from optical emission lines through strong-line method (the theoretical calibration Storchi-Bergmann et al.(1998)), via direct Te-method, and central intersect host galaxies determined radial abundance gradients. found that Te-method underestimates by up to ~2 dex (with average value ~0.8 dex) compared derived method. This confirms existence so-called "temperature...
The results of an optical monitoring campaign on the active nucleus in luminous Seyfert 1 galaxy Fairall 9 are presented. This was undertaken parallel with ultraviolet spectroscopic IUE satellite which is described a separate paper. primary purpose this program to measure response times (or "lags") emission lines continuum variations and thus extend range luminosity galactic nuclei (AGNs) for such measurements have been made. main conclusions work as follows:
We have used the Hubble Space Telescope to measure motion in sky and compute galactocentric orbit of black hole X-ray binary GRO J1655-40. The system moves with a runaway space velocity km s-1 highly eccentric () orbit. was formed disk at distance greater than 3 kpc from Galactic centre must been shot such an by explosion progenitor star. linear momentum kinetic energy this are comparable those solitary neutron stars millisecond pulsars. J1655-40 is first for which there evidence imparted...
We present an observational study about the impacts of interactions in electron density \ion{H}{ii} regions located 7 systems interacting galaxies. The data consist long-slit spectra range 4400-7300 A, obtained with Gemini Multi-Object Spectrograph at South (GMOS). was determined using ratio emission lines [SII]6716/6731. Our results indicate that estimates HII from our sample galaxies are systematically higher than those derived for isolated mean values $N_{\rm e}=24-532$\,$ \rm cm^{-3}$,...
In this paper, we derive oxygen abundance gradients from H ii regions located in 11 galaxies eight systems of close pairs. Long-slit spectra the range 4400–7300 Å were obtained with Gemini Multi-Object Spectrograph at South (GMOS-S). Spatial profiles gaseous phase along galaxy discs using calibrations based on strong emission lines (N2 and O3N2). We found to be significantly flatter for all studied than those typical isolated spiral galaxies. Four objects our sample, AM 1219A, 1256B, 2030A...
We present VLT spectroscopic observations of Gamma-Ray Burst (GRB) 990705 host galaxy and highlight the benefits provided by prompt-phase features GRBs to derive redshifts latter. In spectrum, we indeed detect an emission feature which attribute [OII] 3726/3729 Angstrom doublet unambiguous redshift z=0.8424+/-0.0002 for this galaxy. This is in full agreement with value z~0.86+/-0.17 previously derived using a transient absorption edge discovered X-ray spectrum GRB990705. burst therefore...
The space velocity of a stellar black hole encodes the history its formation and evolution. Here we measure three-dimensional motion microquasar GRS 1915+105, using decade astrometry with NRAO Very Long Baseline Array, together published radial velocity. in Galactic plane deviates from circular rotation by 53-80 ± 8 km s-1, where range covers any specific distance 6-12 kpc. Perpendicular to plane, is only 10 4 s-1. peculiar minimized at 9-10 kpc then nearly direction toward center. We...
We investigate the excitation mechanisms of near-infrared [Fe ii] and H2 emission lines observed in active galactic nuclei (AGNs). built a photoionization model grid considering two-component continuum: one component accounts for ‘big bump’ peaking at 1 Ryd another represents X-ray source that dominates continuum high energies. Photoionization models as ionizing spectral energy distribution obtained from photometric data Seyert 2 Mrk 1066 taken literature were considered. Results these...
The huge star formation events that occur at some galactic centers do not provide enough clues as to their origin, since the morphological signatures of triggering mechanism are smeared out in timescale a few orbital revolutions galaxy core. Our high spatial resolution three-dimensional near-infrared spectroscopy for first time reveals previously known hidden mass concentration is located exactly youngest end giant star-forming arc. This location, inferred average cluster ages, and dynamical...
We present an observational study of the impacts interactions on kinematics, stellar populations and oxygen abundances components galaxy pair AM 2322−821. A fairly symmetric rotation curve for companion (AM 2322B) with a deprojected velocity amplitude 110 km s−1 was obtained, dynamical mass 1.1–1.3 × 1010 M⊙ within radius 4 kpc estimated using this velocity. Asymmetries in radial field were detected companion, very likely due to interaction between galaxies. The main galaxies modelled...
We show that the microquasar LS I +61° 303 is running away from its birth place in a young complex of massive stars. The supernova explosion formed compact object shot out X-ray binary with linear momentum km s-1, which comparable to momenta found solitary runaway neutron stars and millisecond pulsars. properties system motion s-1 imply natal was asymmetric upper limit for mass could have been suddenly ejected ~2 . initial progenitor star inferred depends on whether formation parent stellar...
We present an observational study about the effects of interactions in kinematics, stellar population and abundances components galaxy pair AM 2306-721. Rotation curves for main companion galaxies were obtained, showing a deprojected velocity amplitude 175 185 km s−1, respectively. The interaction between was modelled using numerical N-body/hydrodynamical simulations, with result indicating that current stage merger would be 250 Myr after perigalacticum. spatial variation distribution...
Two-dimensional kinematics of the central region M 83 (NGC 5236) were obtained through three-dimensional NIR spectroscopy with Gemini South telescope.The spatial covered by integral field unit (∼ 5 ′′ × 13 or ∼ 90 240 pc), was centered approximately at center bulge isophotes and oriented SE-NW.The Paβ emission half arcsecond resolution clearly reveals spider-like diagrams around three centers, indicating presence extended masses, which we describe in terms Satoh distributions.One mass...
GMOS-IFU observational data were used to study the detailed two dimensional gas kinematics and morphological structures within ~500x421 pc^2 of active Seyfert 2 galaxy NGC 4501. We provide empirical evidences possible outflowing material from central zones 4501 observer. In addition, we performed a spectral synthesis diagnostic diagram analysis determine respectively dominant stellar population in inner disc this unveil actual nature engine The principal finding work is that regions are...
We have used multi-wavelength observations of high precision to derive the space velocity and compute orbit around Galactic Centre prototype X-ray binary Scorpius X-1. An origin in local spiral arm Milky Way is ruled out. The galactocentric kinematics X-1 similar that most ancient stars globular clusters inner halo. Most probably, this low-mass was formed by a close encounter cluster. However, it cannot be out natal supernova explosion launched into an like from birth place galactic bulge....
Interactions between galaxies are very common. There special types of interactions that produce systems called polar ring (PRGs), composed a lenticular, elliptical or spiral host galaxy, surrounded by stars and gas, orbiting in an approximately plane. In this paper, we study AM 2020–504, PRG with narrow well-defined ring, probably formed accretion material from donor collected the galaxy. Our observational is based on BVRI broad-band imagery as well long-slit spectroscopy wavelength range...
We report first results of an investigation the tidally disturbed galaxy system AM\,546-324, whose two principal galaxies 2MFGC 04711 and AM\,0546-324 (NED02) were previously classified as interacting doubles. This was selected to study interaction ellipticals in a moderately dense environment. provide spectral characteristics present observational effects on morphology, kinematics, stellar population these galaxies. The is based long-slit spectrophotometric data range $\sim$ 4500-8000 $\AA$...
This observational study is about the effects of interaction on kinematics and chemical abundance component galaxies AM 2229−735. system formed by a disc galaxy, NED01, compact perturbed Sb(s)-like NED02, latter showing tail counter-tail arc-shaped feature. could be progenitor polar ring galaxy. The sky-projected very luminous seems to connect galaxies. Our was based BVRI broad-band imagery as well long-slit spectroscopy in wavelength range 4240–8700 Å. We estimated heliocentric radial...
We present an observational study of the interaction effect on dynamics and morphology minor merger AM 1219−430. This work is based r′ g′ images long-slit spectra obtained with Gemini Multi-Object Spectrograph at South Telescope. detected a tidal tail in main galaxy (AM 1219A) bridge material connecting galaxies. In luminosity, 1219A about 3.8 times brighter than secondary 1219B). The surface brightness profile was decomposed into bulge disc components. shows light excess ∼53 per cent due to...
We investigate interaction effects on the dynamics and morphology of galaxy pairs AM 2058-381 1228-260. This work is based r′ images long-slit spectra obtained with Gemini Multi-Object Spectrograph at South Telescope. The luminosity ratio between main (AM 2058A) secondary 2058B) components first pair a factor ∼ 5, while for other pair, 1228A) component 20 times more luminous than 1228B). four galaxies have pseudo-bulges, Sérsic index n < 2. Their observed radial velocities profiles (RVPs)...
The recent detection of a double red giant branch (RGB) in the optical color-magnitude diagram bulge globular cluster HP 1—a more populated, metal-poor, steep corresponding to itself and another that is metal rich curved—led us explore present Letter possibility field stars are captured by orbiting dense regions over several gigayears. Analytical arguments, as well N-body calculations for model 105 M☉ bulgelike environment, suggest significant fraction may consist captures. Metal-poor...