Page 1. Revista Brasileira de Ensino de Fısica, v. 34, n. 1, 1702 (2012) www.sbfisica.org.br Velocidade do som no ar e efeito Doppler em um único experimento (Sound speed in air and Doppler effect in a single experiment) ...
971 SOUTHERN HEMISPHERE SOLAR RADIO HELIOGRAPH HS Sawant1, F. С. R. Fernandes1, J. А. С. F. Neri1, JR Cecatto1, С. Faria1, S. Stephany1, RR Rosa1, M. С Andrade1, E. Ludke2, К. R. Subramanian3, R. Ramesh3, MS Sundrarajan3, MR Sanka ...
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In this paper, I have analysed the subarcsecond polarization structure of two high-z compact steep-spectrum quasars. Morphology suggests that the jets are interacting strongly with intergalactic medium. Models of bending by ram pressure... more
In this paper, I have analysed the subarcsecond polarization structure of two high-z compact steep-spectrum quasars. Morphology suggests that the jets are interacting strongly with intergalactic medium. Models of bending by ram pressure equilibrium in a cooling flow and alignment of magnetic field lines by jet-IGM shock suggest that the CSS jets are light, supersonic and mildly relativistic. Particle energy index variations along the jet suggests replenishment triggered by such interactions.
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The attainment of high-fidelity images obtained with Very Long Baseline Techniques and earth-rotation synthesis is the main observational quest to study the physical properties of cosmic radio sources for various astrophysical and... more
The attainment of high-fidelity images obtained with Very Long Baseline Techniques and earth-rotation synthesis is the main observational quest to study the physical properties of cosmic radio sources for various astrophysical and cosmological purposes. In this paper, I present a method to combine individual array observations in radio continuum mode at 4995 GHz which is successful when obtaining enhanced images of radio sources. The data combining techniques explained here allow to produce synthesis array images which show details which cannot be obtained by standard data processing and observational techniques with individual arrays.
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We present images for the 3.5 mm continuum and HCN (J=1–0) hyperfine line emission from the surroundings of the H ii regions G75.78+0.34 and G75.77+0.34 obtained with the Berkeley Illinois Maryland Association (BIMA) interferometer using... more
We present images for the 3.5 mm continuum and HCN (J=1–0) hyperfine line emission from the surroundings of the H ii regions G75.78+0.34 and G75.77+0.34 obtained with the Berkeley Illinois Maryland Association (BIMA) interferometer using the D configuration at a spatial resolution of ∼18 arcsec and spectral sampling of 0.34 km s−1. The continuum emission of both objects is dominated by free–free emission from the ionized gas surrounding the exciting stars. Dust emission may contribute only a small fraction of the 3.5 mm continuum from G75.78+0.34 and is negligible for G75.77+0.34. The high spectral resolution reached by BIMA allowed us to separate the emission from each hyperfine transition (F=1–1, 2–1 and 0–1), as well as to construct velocity channel maps along each emission-line profile. The HCN flux distributions are similar to those observed for the CO emission but with some knots of high intensities indicating that the HCN traces high-density clouds not seen in CO. The HCN hyperfine line ratios for both H ii regions differ from those predicted theoretically for local thermodynamic equilibrium, probably due to scattering of radiation processes. The velocity channels show that the HCN emission of G75.78+0.34 follows the bipolar molecular outflows previously observed in CO. For G75.77+0.34, the outflowing gas contributes only a small fraction of the HCN emission.
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We present recent radio interferometer measurements of the OH 1612 MHz maser emission from the OH/IR sources OH0.9+1.3 and OH357.31 obtained with the enhanced MERLIN. Some preliminary results are briefly discussed. These results are part... more
We present recent radio interferometer measurements of the OH 1612 MHz maser emission from the OH/IR sources OH0.9+1.3 and OH357.31 obtained with the enhanced MERLIN. Some preliminary results are briefly discussed. These results are part of an on-going observational campaign to obtain the best radio maps of bright OH/IR stars with MERLIN, VLA and VLBA, in order to understand the nature and dynamics of their circumstellar matter and evolution.
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We present images for the 3.5 mm continuum and HCN(J=1-0) hyperfine line emission from the surroundings of the HII regions G75.78+0.34 and G75.77+0.34 obtained with the Berkeley Illinois Maryland Association (BIMA) interferometer using... more
We present images for the 3.5 mm continuum and HCN(J=1-0) hyperfine line emission from the surroundings of the HII regions G75.78+0.34 and G75.77+0.34 obtained with the Berkeley Illinois Maryland Association (BIMA) interferometer using the D configuration at a spatial resolution of 18 arcsec and spectral sampling of 0.34 km/s. The continuum emission of both objects is dominated by free-free emission from the ionized gas surrounding the exciting stars. Dust emission may contribute only a small fraction of the 3.5 mm continuum from G75.78+0.34 and is negligible for G75.77+0.34. The high spectral resolution reached by BIMA allowed us to separate the emission from each hyperfine transition (F=1-1, F=2-1 and F=0-1), as well as to construct velocity channel maps along each emission-line profile. The HCN flux distributions are similar to those observed for the CO emission, but with some knots of high intensities indicating that the HCN traces high density clouds not seen in CO. The HCN hyperfine line ratios for both HII regions differ from those predicted theoretically for Local Thermodynamic Equilibrium (LTE), probably due to scattering of radiation processes. The velocity channels shows that the HCN emission of G75.78+0.34 follows the bipolar molecular outflows previously observed in CO. For G75.77+0.34, the outflowing gas contributes only a small fraction of the HCN emission.
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Research Interests:
In this paper, I present construction details of a spectrophotometric assay operating in visual and ultraviolet wavelengths at a very low cost. The equipment is intended to be used by first or second-year undergraduate students in health... more
In this paper, I present construction details of a spectrophotometric assay operating in visual and ultraviolet wavelengths at a very low cost. The equipment is intended to be used by first or second-year undergraduate students in health sciences during practical activities of methods in analytical chemistry, physical chemistry or biophysics. The experimental learning of fundamental spectrophotometric techniques and the quantitative determination of the Lambert-Beer law, which cannot be done with commercial UV spectrophotometers, is easily attained with the apparatus. Experimental examples in biophysics teaching labs are briefly discussed.
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This work reports our recent results of an HI line and radio continuum imaging survey of selected southern Active galaxies made with the Very Large Array and the Australian Telescope Compact Array. Radio images are presented and rotation... more
This work reports our recent results of an HI line and radio continuum imaging survey of selected southern Active galaxies made with the Very Large Array and the Australian Telescope Compact Array. Radio images are presented and rotation curves for individual galaxies were obtained. The HI total mass content in Seyfert galaxies is larger than those seen in starburst galaxies. Our trends confirm that the infrared luminosity correlates well with the total neutral gas content, which supports the scenario that star formation in the bulges of Seyfert galaxies is considerably higher than in regular late-type galaxies or spirals. We also find a trend between various observational quantities which are also discussed in this work.
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We use new optical and near-infrared data to identify the radio source 4C 13.66 with a K=18.2 galaxy at z=1.45, and use new radio images to study its relatively unusual radio structure. Prior to this work 4C 13.66 was the only radio... more
We use new optical and near-infrared data to identify the radio source 4C 13.66 with a K=18.2 galaxy at z=1.45, and use new radio images to study its relatively unusual radio structure. Prior to this work 4C 13.66 was the only radio source out of 173 in the revised 3C sample of Laing, Riley & Longair without a spectroscopic redshift. We discuss the vital role of near-infrared spectroscopy in securing the final redshift for this sample.
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MERLIN observations of the compact steep-spectrum quasar 3C 138 at 0.151, 0.408, 1.666 and 4.995 GHz, a combined MERLIN-EVN image at 1.666 GHz and VLA polarisation images at 22.5 GHz are presented. The radio structure is unresolved at... more
MERLIN observations of the compact steep-spectrum quasar 3C 138 at 0.151, 0.408, 1.666 and 4.995 GHz, a combined MERLIN-EVN image at 1.666 GHz and VLA polarisation images at 22.5 GHz are presented. The radio structure is unresolved at 0.151 and 0.408 GHz and shows no diffuse extended halo. At high frequencies its structure is largely linear and dominated by five distinct knots and compact components. We identify the two terminal components as compact radio lobes and infer that 3C 138 is a small double source with a two-sided jet structure rather than a `naked- jet'. The unusual steepening of the radio spectrum away from the nucleus is consistent with a young source, perhaps with dense jets, that has as yet not formed back-flowing cocoon associated with classical FRII radio sources. We also calculate the physical parameters in the components.
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In this paper we present results of a detailed morphological and radio polarization study of the nearby radio galaxy 3C33.1 (4C72.01, 0106+729, z = 0.18) made with the Very Large Array at 18 and 21 cm. Recently, this galaxy has been... more
In this paper we present results of a detailed morphological and radio polarization study of the nearby radio galaxy 3C33.1 (4C72.01, 0106+729, z = 0.18) made with the Very Large Array at 18 and 21 cm. Recently, this galaxy has been re-classified within a sample of large core-dominated radio sources and it has an exceedingly high projected linear size of ˜450 kpc. The jet shows little Faraday rotation, with rotation measures |RM|<20 rad m-2, whereas the hotspots exhibit higher values. The low rotation measures indicate that this radio source has a visible jet, which can be a naked jet or stripped from a dense environment. A spectral ageing analysis, based on syncrotron power losses arguments of the integrated spectra, suggest that the radio structure is not younger than 20 Myrs. Further observational properties of this radio galaxy are also discussed.
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... 222, 2004© 2004 International Astronomical Union T. Storchi-Bergmann, LC Ho & HR Schmitt. eds. DOI: 10.1017/S1743921304002327 HI observations of nearby southern Seyfert galaxies with the ATNF/Mopra radiotelescope Alcides GR... more
... 222, 2004© 2004 International Astronomical Union T. Storchi-Bergmann, LC Ho & HR Schmitt. eds. DOI: 10.1017/S1743921304002327 HI observations of nearby southern Seyfert galaxies with the ATNF/Mopra radiotelescope Alcides GR Adornes1, Rosane Bohrer-Adornes1 ...
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We present the technical characteristics of a low-cost radio telescope for solar/non solar observations at decimetric (1200 1700 MHz) and centimetric (2700 and 5000 MHz) wavelengths known as Brazilian Decimetric Array (BDA). The technical... more
We present the technical characteristics of a low-cost radio telescope for solar/non solar observations at decimetric (1200 1700 MHz) and centimetric (2700 and 5000 MHz) wavelengths known as Brazilian Decimetric Array (BDA). The technical specifications of the antenna, tracking system, log-periodic feed, preamplifier and the frequency-synthesised receiver with a Single Side Band (SSB) video output of 2.5 MHz are given.
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We present polarization observations of 28 compact steep-spectrum sources made with the upgraded MERLIN at 5 GHz. With an angular resolution of 60 milliarcsec and rms noise levels of about 0.1 mJy beam−1, the total intensity images reveal... more
We present polarization observations of 28 compact steep-spectrum sources made with the upgraded MERLIN at 5 GHz. With an angular resolution of 60 milliarcsec and rms noise levels of about 0.1 mJy beam−1, the total intensity images reveal new details in many of these sources. A few of the more extended lobes and jets are quite highly polarized, but more than half of the components are completely unpolarized. Comparison with published data implies that this is due to Faraday depolarization, probably occurring in the surrounding medium with nB ∼ 1 cm−3μG. The high resolution of the present observations implies that the variations in Faraday rotation, probably due to magnetic field tangling, occur on scales of less than about 100 pc.
A radio heliograph operating in the frequency range of 1200–1700 MHz is planned by INPE, Brazil, for investigations of time evolution of active regions, which will lead to better understanding of the physics of the flares energy release... more
A radio heliograph operating in the frequency range of 1200–1700 MHz is planned by INPE, Brazil, for investigations of time evolution of active regions, which will lead to better understanding of the physics of the flares energy release and particle acceleration, in order to suggest better criteria for the prediction of solar flares, Coronal Mass Ejections (CME), and solar terrestrial relations, such as geomagnetic storms and radio blackouts. In the first phase, the Brazilian Decimetric Array (BDA) will be a T shaped array 256 m by 144 m, consisting of 26 parabolic dish antennas of 4 m diameter. This array will produce full disk images of the sun with a spatial resolution of 3 by 5 arc minutes at 1420 MHz with a time resolution of 100 ms and sensitivity of ∼ 10 Jy. In the second phase, in addition to the compact T array there will be 6 more 7 m diameter antennas on an East-West baseline of 2560 m to obtain higher spatial resolution and better sensitivity. Thus, finally this radioheliograph will have wide field of view and couple of arcsec spatial resolution and high time resolution (100 ms).