Fine analysis of the silicon star HD 206653 is presented using ATLAS9 model atmospheres whose pre... more Fine analysis of the silicon star HD 206653 is presented using ATLAS9 model atmospheres whose predictions fit the observational data and have the same bulk metallicity as the deduced abundances. The abundances derived are discussed in the scenary of the difussion theory.
Revista Mexicana De Astronomia Y Astrofisica - REV MEX ASTRON ASTROFIS, 2005
We compared elemental abundances of field and open cluster Ap Si stars. In particular, an analysi... more We compared elemental abundances of field and open cluster Ap Si stars. In particular, an analysis of the Ap Si stars HD 87240 and HD 96729 is presented using an ATLAS9 model atmosphere and observational material taken with a REOSC echelle spectrograph attached to the Jorge Sahade 2.15 m telescope at CASLEO. These chemically peculiar (CP) stars belong to the southern hemisphere open clusters NGC 3114 and NGC 3532, respectively. For HD 87240 and HD 96729, C is mostly solar, Mg and S are slightly underabundant, Si and Ca are overabundant by factors between 1--10. Heavier elements are all overabundant, TiCrFe by factors of ˜ 10, SrYZr by factors between 100--1000 and rare earths by factors of ˜ 1000 or more.
New striking aspects of solar activity have been found from observations at frequencies above 100... more New striking aspects of solar activity have been found from observations at frequencies above 100 GHz, provided by the solar submillimeter-wave telescope (SST) at El Leoncito in the Argentina Andes. The SST utilizes a radome-enclosed 1.5-m Cassegrain reflector, operating simultaneously with four 212 GHz and two 405 GHz total power radiometers with 5ms time resolution. Partial overlapping of antenna beams
Proceedings of the International Astronomical Union, 2005
This report from Commission 30 covers the salient areas in which major progress has been made in ... more This report from Commission 30 covers the salient areas in which major progress has been made in the triennium covered by the present volume. The principal scientific areas are: The Milky Way, star clusters, spectroscopic binaries, extrasolar planets, pulsating stars and stellar oscillations. Following these, an account is given of the progress in techniques and methodology for radial velocity determinations.
IEEE Transactions on Antennas and Propagation, 2005
We present the results of one year of daytime atmosphere transmission measurements obtained at 21... more We present the results of one year of daytime atmosphere transmission measurements obtained at 212 and 405 GHz by a 1.5 m solar radio telescope located at El Leoncito site, 2550 m altitude in Argentina Andes. We used three different methods: 1) absolute derivation from strong solar signal at different elevation angles; 2) direct derivation from observed known solar brightness
Proceedings of the International Astronomical Union, 2009
In this work, we analyze observations of the solar radius at 22 and 43 GHz obtained with the 13.7... more In this work, we analyze observations of the solar radius at 22 and 43 GHz obtained with the 13.7 m antenna of the Itapetinga Radio Observatory (Atibaia, Brazil) and at submillimeter-wave frequencies, 212 and 405 GHz, obtained by the Solar Submillimeter-wave Telescope (SST) (El Leoncito, San Juan, Argentina). The radius is defined as the limb position where the intensity is
We report properties of fast varying submillimeter emission during the strongest solar radio flar... more We report properties of fast varying submillimeter emission during the strongest solar radio flare of solar cycle 23. Emission were obtained by the Submillimeter Wave Telescope at 212 GHz and 405 GHz and compared with hard X-ray and gamma-ray counts up to few tens of MeV photon energy ranges. We employ different methods to detect and characterize flux density variations,
Abstract. With the approval of funds for the development and construction of the new Solar Submm-... more Abstract. With the approval of funds for the development and construction of the new Solar Submm-wave Telescope, its design was reviewed, updated and manufac-turers for the subsystems were selected. The principal characteristics of the system and the proposed research ...
We measured projected rotational velocities for nearly 1100 B stars with these results. (1) They ... more We measured projected rotational velocities for nearly 1100 B stars with these results. (1) They average substantially less than those published in the Bright Star Catalogue and are about one-quarter of the break-up velocities. (2) For the late B stars the deconvolved distribution in V is bimodal; one lobe consists of rapidly-rotating normal stars and the other lobe of slowly-rotating
Proceedings of the International Astronomical Union, 2007
The current content of the database was presented, emphasising the substantial progress accomplis... more The current content of the database was presented, emphasising the substantial progress accomplished since the IAU XXIV General Assembly in Manchester, 2000. More than 1 200 stellar systems have been added to the 8th Catalogue over the past six years, for a total of 540 papers compiled. A first paper was published to make the community aware of this facility (Pourbaix et al. 2004).
We present a bibliographic catalogue of stellar radial velocities with 13359 entries for stars in... more We present a bibliographic catalogue of stellar radial velocities with 13359 entries for stars in the galaxy and the Magellanic Clouds, obtained from the issues of several journals published in the period 1991-1994. We have tried to follow the structure of previous compilations although we have relied on data retrived from the SIMBAD database. Catalogue available at the CDS via
Fine analysis of the silicon star HD 206653 is presented using ATLAS9 model atmospheres whose pre... more Fine analysis of the silicon star HD 206653 is presented using ATLAS9 model atmospheres whose predictions fit the observational data and have the same bulk metallicity as the deduced abundances. The abundances derived are discussed in the scenary of the difussion theory.
Revista Mexicana De Astronomia Y Astrofisica - REV MEX ASTRON ASTROFIS, 2005
We compared elemental abundances of field and open cluster Ap Si stars. In particular, an analysi... more We compared elemental abundances of field and open cluster Ap Si stars. In particular, an analysis of the Ap Si stars HD 87240 and HD 96729 is presented using an ATLAS9 model atmosphere and observational material taken with a REOSC echelle spectrograph attached to the Jorge Sahade 2.15 m telescope at CASLEO. These chemically peculiar (CP) stars belong to the southern hemisphere open clusters NGC 3114 and NGC 3532, respectively. For HD 87240 and HD 96729, C is mostly solar, Mg and S are slightly underabundant, Si and Ca are overabundant by factors between 1--10. Heavier elements are all overabundant, TiCrFe by factors of ˜ 10, SrYZr by factors between 100--1000 and rare earths by factors of ˜ 1000 or more.
New striking aspects of solar activity have been found from observations at frequencies above 100... more New striking aspects of solar activity have been found from observations at frequencies above 100 GHz, provided by the solar submillimeter-wave telescope (SST) at El Leoncito in the Argentina Andes. The SST utilizes a radome-enclosed 1.5-m Cassegrain reflector, operating simultaneously with four 212 GHz and two 405 GHz total power radiometers with 5ms time resolution. Partial overlapping of antenna beams
Proceedings of the International Astronomical Union, 2005
This report from Commission 30 covers the salient areas in which major progress has been made in ... more This report from Commission 30 covers the salient areas in which major progress has been made in the triennium covered by the present volume. The principal scientific areas are: The Milky Way, star clusters, spectroscopic binaries, extrasolar planets, pulsating stars and stellar oscillations. Following these, an account is given of the progress in techniques and methodology for radial velocity determinations.
IEEE Transactions on Antennas and Propagation, 2005
We present the results of one year of daytime atmosphere transmission measurements obtained at 21... more We present the results of one year of daytime atmosphere transmission measurements obtained at 212 and 405 GHz by a 1.5 m solar radio telescope located at El Leoncito site, 2550 m altitude in Argentina Andes. We used three different methods: 1) absolute derivation from strong solar signal at different elevation angles; 2) direct derivation from observed known solar brightness
Proceedings of the International Astronomical Union, 2009
In this work, we analyze observations of the solar radius at 22 and 43 GHz obtained with the 13.7... more In this work, we analyze observations of the solar radius at 22 and 43 GHz obtained with the 13.7 m antenna of the Itapetinga Radio Observatory (Atibaia, Brazil) and at submillimeter-wave frequencies, 212 and 405 GHz, obtained by the Solar Submillimeter-wave Telescope (SST) (El Leoncito, San Juan, Argentina). The radius is defined as the limb position where the intensity is
We report properties of fast varying submillimeter emission during the strongest solar radio flar... more We report properties of fast varying submillimeter emission during the strongest solar radio flare of solar cycle 23. Emission were obtained by the Submillimeter Wave Telescope at 212 GHz and 405 GHz and compared with hard X-ray and gamma-ray counts up to few tens of MeV photon energy ranges. We employ different methods to detect and characterize flux density variations,
Abstract. With the approval of funds for the development and construction of the new Solar Submm-... more Abstract. With the approval of funds for the development and construction of the new Solar Submm-wave Telescope, its design was reviewed, updated and manufac-turers for the subsystems were selected. The principal characteristics of the system and the proposed research ...
We measured projected rotational velocities for nearly 1100 B stars with these results. (1) They ... more We measured projected rotational velocities for nearly 1100 B stars with these results. (1) They average substantially less than those published in the Bright Star Catalogue and are about one-quarter of the break-up velocities. (2) For the late B stars the deconvolved distribution in V is bimodal; one lobe consists of rapidly-rotating normal stars and the other lobe of slowly-rotating
Proceedings of the International Astronomical Union, 2007
The current content of the database was presented, emphasising the substantial progress accomplis... more The current content of the database was presented, emphasising the substantial progress accomplished since the IAU XXIV General Assembly in Manchester, 2000. More than 1 200 stellar systems have been added to the 8th Catalogue over the past six years, for a total of 540 papers compiled. A first paper was published to make the community aware of this facility (Pourbaix et al. 2004).
We present a bibliographic catalogue of stellar radial velocities with 13359 entries for stars in... more We present a bibliographic catalogue of stellar radial velocities with 13359 entries for stars in the galaxy and the Magellanic Clouds, obtained from the issues of several journals published in the period 1991-1994. We have tried to follow the structure of previous compilations although we have relied on data retrived from the SIMBAD database. Catalogue available at the CDS via
Uploads
Papers by Hugo Levato