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Papers by Gabriel Ferrero

Se ha desarrollado un procedimiento experimental capaz de aumentar en un factor de 50 la permeabi... more Se ha desarrollado un procedimiento experimental capaz de aumentar en un factor de 50 la permeabilidad magnetica de barras de mumetal (Ni 77 Fe 14 Cu 5 Mo 4 ). El procedimiento consiste en un tratamiento termico bajo atmosfera inerte, para el cual se diseno y construyo un control automatico de temperatura programable de alta precision. En el curso de los tratamientos se ha verificado que el sistema es capaz de mantener una temperatura estable de mas de 1000 °C con un error menor que 2 °C y con gradientes lineales menores del 1%. Ademas se diseno y construyo un permeametro con fluxometro electronico con el cual se verifico la permeabilidad magnetica alcanzada. La barra tratada se utilizo para construir un magnetopar (magnetic torquer) para satelite. El instrumento producido desarrolla un momento dipolar magnetico maximo de 25 Am2 en su zona lineal con un consumo de menos de 0.3 W de potencia y una masa de 2.1 kg. Aprovechando la interaccion de los magnetopares con el campo magnetico ...

In O+OB close binary systems, a secular motion of the apsides arises from orbital perturbations d... more In O+OB close binary systems, a secular motion of the apsides arises from orbital perturbations due to superior order momenta of the gravitational classical potential and general relativity effects. This phenomenon and theoretical stellar structure models, can be used to estimate absolute masses of the system components, even for non-eclipsing binaries. This project aims to establish the feasibility of this mass determination method in all the massive close binary stars for which it could be applied. In this work we briefly describe the selection criteria of the systems to be studied, the sampling status of their radial velocity curves, the adopted procedures for spectroscopic data reduction, and few preliminary results.

The Astrophysical Journal Supplement Series

We present spectroscopic measurements for 226 sources from the Gemini Near Infrared Spectrograph-... more We present spectroscopic measurements for 226 sources from the Gemini Near Infrared Spectrograph-Distant Quasar Survey (GNIRS-DQS). Being the largest uniform, homogeneous survey of its kind, it represents a flux-limited sample (m i 19.0 mag, H 16.5 mag) of Sloan Digital Sky Survey (SDSS) quasars at 1.5 z 3.5 with a monochromatic luminosity (λL λ) at 5100Å in the range of 10 44 − 10 46 erg s −1. A combination of the GNIRS and SDSS spectra covers principal quasar diagnostic features, chiefly the C iv λ1549, Mg ii λλ2798, 2803, Hβ λ4861, and [O iii] λλ4959, 5007 emission lines, in each source. The spectral inventory will be utilized primarily to develop prescriptions for obtaining more accurate and precise redshifts, black hole masses, and accretion rates for all quasars. Additionally, the measurements will facilitate an understanding of the dependence of rest-frame ultraviolet-optical spectral properties of quasars on redshift, luminosity, and Eddington ratio, and test whether the physical properties of the quasar central engine evolve over cosmic time.

Monthly Notices of the Royal Astronomical Society

We introduce the Ophiuchus DIsc Survey Employing ALMA (ODISEA), a project aiming to study the ent... more We introduce the Ophiuchus DIsc Survey Employing ALMA (ODISEA), a project aiming to study the entire population of Spitzer-selected protoplanetary discs in the Ophiuchus Molecular Cloud (∼300 objects) from both millimetre continuum and CO isotopologues data. Here we present 1.3 mm/230 GHz continuum images of 147 targets at 0.2 arcsec (28 au) resolution and a typical rms of 0.15 mJy. We detect a total of 133 discs, including the individual components of 11 binary systems and 1 triple system. 60 of these discs are spatially resolved. We find clear substructures (inner cavities, rings, gaps, and/or spiral arms) in eight of the sources and hints of such structures in another four discs. We construct the disc luminosity function for our targets and perform preliminary comparisons to other regions. A simple conversion between flux and dust mass (adopting standard assumptions) indicates that all discs detected at 1.3 mm are massive enough to form one or more rocky planets. In contrast, only ∼50 discs (∼1/3 of the sample) have enough mass in the form of dust to form the canonical 10 M ⊕ core needed to trigger runaway gas accretion and the formation of gas giant planets, although the total mass of solids already incorporated into bodies larger than cm scales is mostly unconstrained. The distribution in continuum disc sizes in our sample is heavily weighted towards compact discs: most detected discs have radii < 15 au, while only 23 discs (∼15 per cent of the targets) have radii > 30 au.

The Astrophysical Journal

Revista De Investigacion De Fisica, Aug 13, 2014

ABSTRACT IAUC 9082 available at Central Bureau for Astronomical Telegrams.

Journal of the American …, 2001

44 Garcia eta!., fAA VSO Volume 30, 2001 EVIDENCE FOR PERIOD CHANGE IN V393 CARINAE Jaime Ruben G... more 44 Garcia eta!., fAA VSO Volume 30, 2001 EVIDENCE FOR PERIOD CHANGE IN V393 CARINAE Jaime Ruben Garcia Instituto Copérnico Casilla de Correos Nro. 85 5600 San Rafael-Mendoza Argentina Victor Angel Busso Observatorio AstronOmico del Colegio Cristo Rey Laprida ...

Journal of the American …, 2001

44 Garcia eta!., fAA VSO Volume 30, 2001 EVIDENCE FOR PERIOD CHANGE IN V393 CARINAE Jaime Ruben G... more 44 Garcia eta!., fAA VSO Volume 30, 2001 EVIDENCE FOR PERIOD CHANGE IN V393 CARINAE Jaime Ruben Garcia Instituto Copérnico Casilla de Correos Nro. 85 5600 San Rafael-Mendoza Argentina Victor Angel Busso Observatorio AstronOmico del Colegio Cristo Rey Laprida ...

Revista mexicana de astronomía y astrofísica

We obtained several images of SN 2003gf at the Marangani Observatory (Peru) on the night 3-4 July... more We obtained several images of SN 2003gf at the Marangani Observatory (Peru) on the night 3-4 July 2003 from which we have estimated its brightness in the V band, as 15.10±0.09 mag. This was obtained after a proper calibration of the starfield, considering the photometric data of the infrared bands of the 2MASS catalog. The precision achieved shows a reasonable agreement with measurements by other observers.

Radial velocity (RV) measurements of primary (A) and secondary (B) components of HD 165052 obtain... more Radial velocity (RV) measurements of primary (A) and secondary (B) components of HD 165052 obtained by disentangling method (Gonzalez & Levato, 2006A&A...448..283G). 37 high-resolution spectra were acquired with: mainly with the REOSC-DC spectrograph at 2.15-m Sahade telescope (CASLEO, Argentina) between 2008 August and 2010 August; and with the echelle spectrograph at 2.5-m Du-Pont tel. (LCO, Chile) in May 2010; and FEROS at 2.2-m tel. (ESO-La Silla, Chile) in 2009 May. Cross-correlation was calculated over a disjoint sample region composed of 17 wavelength intervals, each ~1nm wide, taken around the spectral lines indicated. RVs measured in this mode are listed as mean RVs. Subsequently we have defined several sampling regions, each one around a single spectral line, and computed cross-correlation separately for each one. These are the RVs listed for each line. (1 data file).

Resumen Utilizando datos meteorológicos globales de diferentes fuentes, que cubren observaciones ... more Resumen Utilizando datos meteorológicos globales de diferentes fuentes, que cubren observaciones realizadas a lo largo de los últimos 40 años, y usando también imágenes satelitales recientes, se están buscando los mejores sitios astronómicos para observaciones de micro-variabilidad estelar y del Sol en diferentes bandas. Un conjunto de zonas potenciales con condiciones astroclimatológicas favorables ha sido identificado y un estudio de la cobertura nubosa en esas zonas fue hecho usando resultados previos de la bases de datos Surface meterology and Solar Energy, International Satellite Land-Surface Climatology Project e imágenes satelitales infrarrojas GOES. Los datos satelitales están siendo validados con mediciones desde tierra de las variables meteorológicos habiendo obtenido una buena correlación estadística. Considerando también aspectos topográficos, sismológicos, vulcanológicos y logísticos, algunos sitios interesantes han sido seleccionados para un análisis adicional. En uno ...

Be objects are stars of B spectral type showing lines of the Balmer series in emission. The prese... more Be objects are stars of B spectral type showing lines of the Balmer series in emission. The presence of these lines is attributed to the existence of an extended envelope, disk type, around them. Some stars are observed in both the Be and normal B-type spectroscopic states and they are known as transient Be stars. In this paper we show the analysis carried out on a new possible transient Be star, labelled HD 112999, using spectroscopic optical observations and photometric data.

In O+OB close binary systems, a secular motion of the apsides arises from orbital perturbations d... more In O+OB close binary systems, a secular motion of the apsides arises from orbital perturbations due to superior order momenta of the gravitational classical potential and general relativity effects. This phenomenon and theoretical stellar structure models, can be used to estimate absolute masses of the system components, even for non-eclipsing binaries. This project aims to establish the feasibility of this mass determination method in all the massive close binary stars for which it could be applied. In this work we briefly describe the selection criteria of the systems to be studied, the sampling status of their radial velocity curves, the adopted procedures for spectroscopic data reduction, and few preliminary results.

ABSTRACT IAUC 9082 available at Central Bureau for Astronomical Telegrams.

Se ha desarrollado un procedimiento experimental capaz de aumentar en un factor de 50 la permeabi... more Se ha desarrollado un procedimiento experimental capaz de aumentar en un factor de 50 la permeabilidad magnetica de barras de mumetal (Ni 77 Fe 14 Cu 5 Mo 4 ). El procedimiento consiste en un tratamiento termico bajo atmosfera inerte, para el cual se diseno y construyo un control automatico de temperatura programable de alta precision. En el curso de los tratamientos se ha verificado que el sistema es capaz de mantener una temperatura estable de mas de 1000 °C con un error menor que 2 °C y con gradientes lineales menores del 1%. Ademas se diseno y construyo un permeametro con fluxometro electronico con el cual se verifico la permeabilidad magnetica alcanzada. La barra tratada se utilizo para construir un magnetopar (magnetic torquer) para satelite. El instrumento producido desarrolla un momento dipolar magnetico maximo de 25 Am2 en su zona lineal con un consumo de menos de 0.3 W de potencia y una masa de 2.1 kg. Aprovechando la interaccion de los magnetopares con el campo magnetico ...

In O+OB close binary systems, a secular motion of the apsides arises from orbital perturbations d... more In O+OB close binary systems, a secular motion of the apsides arises from orbital perturbations due to superior order momenta of the gravitational classical potential and general relativity effects. This phenomenon and theoretical stellar structure models, can be used to estimate absolute masses of the system components, even for non-eclipsing binaries. This project aims to establish the feasibility of this mass determination method in all the massive close binary stars for which it could be applied. In this work we briefly describe the selection criteria of the systems to be studied, the sampling status of their radial velocity curves, the adopted procedures for spectroscopic data reduction, and few preliminary results.

The Astrophysical Journal Supplement Series

We present spectroscopic measurements for 226 sources from the Gemini Near Infrared Spectrograph-... more We present spectroscopic measurements for 226 sources from the Gemini Near Infrared Spectrograph-Distant Quasar Survey (GNIRS-DQS). Being the largest uniform, homogeneous survey of its kind, it represents a flux-limited sample (m i 19.0 mag, H 16.5 mag) of Sloan Digital Sky Survey (SDSS) quasars at 1.5 z 3.5 with a monochromatic luminosity (λL λ) at 5100Å in the range of 10 44 − 10 46 erg s −1. A combination of the GNIRS and SDSS spectra covers principal quasar diagnostic features, chiefly the C iv λ1549, Mg ii λλ2798, 2803, Hβ λ4861, and [O iii] λλ4959, 5007 emission lines, in each source. The spectral inventory will be utilized primarily to develop prescriptions for obtaining more accurate and precise redshifts, black hole masses, and accretion rates for all quasars. Additionally, the measurements will facilitate an understanding of the dependence of rest-frame ultraviolet-optical spectral properties of quasars on redshift, luminosity, and Eddington ratio, and test whether the physical properties of the quasar central engine evolve over cosmic time.

Monthly Notices of the Royal Astronomical Society

We introduce the Ophiuchus DIsc Survey Employing ALMA (ODISEA), a project aiming to study the ent... more We introduce the Ophiuchus DIsc Survey Employing ALMA (ODISEA), a project aiming to study the entire population of Spitzer-selected protoplanetary discs in the Ophiuchus Molecular Cloud (∼300 objects) from both millimetre continuum and CO isotopologues data. Here we present 1.3 mm/230 GHz continuum images of 147 targets at 0.2 arcsec (28 au) resolution and a typical rms of 0.15 mJy. We detect a total of 133 discs, including the individual components of 11 binary systems and 1 triple system. 60 of these discs are spatially resolved. We find clear substructures (inner cavities, rings, gaps, and/or spiral arms) in eight of the sources and hints of such structures in another four discs. We construct the disc luminosity function for our targets and perform preliminary comparisons to other regions. A simple conversion between flux and dust mass (adopting standard assumptions) indicates that all discs detected at 1.3 mm are massive enough to form one or more rocky planets. In contrast, only ∼50 discs (∼1/3 of the sample) have enough mass in the form of dust to form the canonical 10 M ⊕ core needed to trigger runaway gas accretion and the formation of gas giant planets, although the total mass of solids already incorporated into bodies larger than cm scales is mostly unconstrained. The distribution in continuum disc sizes in our sample is heavily weighted towards compact discs: most detected discs have radii < 15 au, while only 23 discs (∼15 per cent of the targets) have radii > 30 au.

The Astrophysical Journal

Revista De Investigacion De Fisica, Aug 13, 2014

ABSTRACT IAUC 9082 available at Central Bureau for Astronomical Telegrams.

Journal of the American …, 2001

44 Garcia eta!., fAA VSO Volume 30, 2001 EVIDENCE FOR PERIOD CHANGE IN V393 CARINAE Jaime Ruben G... more 44 Garcia eta!., fAA VSO Volume 30, 2001 EVIDENCE FOR PERIOD CHANGE IN V393 CARINAE Jaime Ruben Garcia Instituto Copérnico Casilla de Correos Nro. 85 5600 San Rafael-Mendoza Argentina Victor Angel Busso Observatorio AstronOmico del Colegio Cristo Rey Laprida ...

Journal of the American …, 2001

44 Garcia eta!., fAA VSO Volume 30, 2001 EVIDENCE FOR PERIOD CHANGE IN V393 CARINAE Jaime Ruben G... more 44 Garcia eta!., fAA VSO Volume 30, 2001 EVIDENCE FOR PERIOD CHANGE IN V393 CARINAE Jaime Ruben Garcia Instituto Copérnico Casilla de Correos Nro. 85 5600 San Rafael-Mendoza Argentina Victor Angel Busso Observatorio AstronOmico del Colegio Cristo Rey Laprida ...

Revista mexicana de astronomía y astrofísica

We obtained several images of SN 2003gf at the Marangani Observatory (Peru) on the night 3-4 July... more We obtained several images of SN 2003gf at the Marangani Observatory (Peru) on the night 3-4 July 2003 from which we have estimated its brightness in the V band, as 15.10±0.09 mag. This was obtained after a proper calibration of the starfield, considering the photometric data of the infrared bands of the 2MASS catalog. The precision achieved shows a reasonable agreement with measurements by other observers.

Radial velocity (RV) measurements of primary (A) and secondary (B) components of HD 165052 obtain... more Radial velocity (RV) measurements of primary (A) and secondary (B) components of HD 165052 obtained by disentangling method (Gonzalez & Levato, 2006A&A...448..283G). 37 high-resolution spectra were acquired with: mainly with the REOSC-DC spectrograph at 2.15-m Sahade telescope (CASLEO, Argentina) between 2008 August and 2010 August; and with the echelle spectrograph at 2.5-m Du-Pont tel. (LCO, Chile) in May 2010; and FEROS at 2.2-m tel. (ESO-La Silla, Chile) in 2009 May. Cross-correlation was calculated over a disjoint sample region composed of 17 wavelength intervals, each ~1nm wide, taken around the spectral lines indicated. RVs measured in this mode are listed as mean RVs. Subsequently we have defined several sampling regions, each one around a single spectral line, and computed cross-correlation separately for each one. These are the RVs listed for each line. (1 data file).

Resumen Utilizando datos meteorológicos globales de diferentes fuentes, que cubren observaciones ... more Resumen Utilizando datos meteorológicos globales de diferentes fuentes, que cubren observaciones realizadas a lo largo de los últimos 40 años, y usando también imágenes satelitales recientes, se están buscando los mejores sitios astronómicos para observaciones de micro-variabilidad estelar y del Sol en diferentes bandas. Un conjunto de zonas potenciales con condiciones astroclimatológicas favorables ha sido identificado y un estudio de la cobertura nubosa en esas zonas fue hecho usando resultados previos de la bases de datos Surface meterology and Solar Energy, International Satellite Land-Surface Climatology Project e imágenes satelitales infrarrojas GOES. Los datos satelitales están siendo validados con mediciones desde tierra de las variables meteorológicos habiendo obtenido una buena correlación estadística. Considerando también aspectos topográficos, sismológicos, vulcanológicos y logísticos, algunos sitios interesantes han sido seleccionados para un análisis adicional. En uno ...

Be objects are stars of B spectral type showing lines of the Balmer series in emission. The prese... more Be objects are stars of B spectral type showing lines of the Balmer series in emission. The presence of these lines is attributed to the existence of an extended envelope, disk type, around them. Some stars are observed in both the Be and normal B-type spectroscopic states and they are known as transient Be stars. In this paper we show the analysis carried out on a new possible transient Be star, labelled HD 112999, using spectroscopic optical observations and photometric data.

In O+OB close binary systems, a secular motion of the apsides arises from orbital perturbations d... more In O+OB close binary systems, a secular motion of the apsides arises from orbital perturbations due to superior order momenta of the gravitational classical potential and general relativity effects. This phenomenon and theoretical stellar structure models, can be used to estimate absolute masses of the system components, even for non-eclipsing binaries. This project aims to establish the feasibility of this mass determination method in all the massive close binary stars for which it could be applied. In this work we briefly describe the selection criteria of the systems to be studied, the sampling status of their radial velocity curves, the adopted procedures for spectroscopic data reduction, and few preliminary results.

ABSTRACT IAUC 9082 available at Central Bureau for Astronomical Telegrams.