http://sedici.unlp.edu.ar:80/handle/10915/78369 Sun, 11 Oct 2026 19:52:38 GMT 2026-10-11T19:52:38Z http://sedici.unlp.edu.ar:80/handle/10915/141874 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 A diario la naturaleza nos muestra, que nada es espontáneo ni individual, que un todo se compone a través del tiempo con la contribución adecuada de las partes. Así, la Ciencia y la Tecnología, debieron pasar indudablemente hasta nuestros días, por etapas sucesivas y esfuerzos mancomunados. La Astronomía, como conjunto de conocimientos, constituye un ejemplo cabal de evolución sistemática. El Cosmos, como conjunto de cosas creadas y ordenadas, sintetiza este concepto e involucra al hombre como ser inteligente del universo que lo rodea. Por lo tanto, el Orden obliga a la composición de las partes y éstas, como principio de todas las cosas, conforme el producto. Similarmente, el Científico, el que se dedica a las Ciencias Físicas, Exactas o Astronómicas, recurre permanentemente a las fuentes de información a fin de obtener datos y partes constitutivas del objeto de su estudio. De esta manera, distribuye, compara y ordena: supone y arriba a una Tesis. El trabajo individual de un estudio, poco o nada reporta. En cambio, si esa acción se una a otra y ésta a una tercera, constituye una fuerza de conjunto y positiva valoración. Por eso la labor de Profesionales y Aficionados debe asociarse en procura de un solo objetivo: la Astronomía. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141874 1987-01-01T00:00:00Z A diario la naturaleza nos muestra, que nada es espontáneo ni individual, que un todo se compone a través del tiempo con la contribución adecuada de las partes. Así, la Ciencia y la Tecnología, debieron pasar indudablemente hasta nuestros días, por etapas sucesivas y esfuerzos mancomunados. La Astronomía, como conjunto de conocimientos, constituye un ejemplo cabal de evolución sistemática. El Cosmos, como conjunto de cosas creadas y ordenadas, sintetiza este concepto e involucra al hombre como ser inteligente del universo que lo rodea. Por lo tanto, el Orden obliga a la composición de las partes y éstas, como principio de todas las cosas, conforme el producto. Similarmente, el Científico, el que se dedica a las Ciencias Físicas, Exactas o Astronómicas, recurre permanentemente a las fuentes de información a fin de obtener datos y partes constitutivas del objeto de su estudio. De esta manera, distribuye, compara y ordena: supone y arriba a una Tesis. El trabajo individual de un estudio, poco o nada reporta. En cambio, si esa acción se una a otra y ésta a una tercera, constituye una fuerza de conjunto y positiva valoración. Por eso la labor de Profesionales y Aficionados debe asociarse en procura de un solo objetivo: la Astronomía. http://sedici.unlp.edu.ar:80/handle/10915/141873 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 El presente trabajo está basado en observaciones realizadas en el lugar denominado "Campo del Cielo", geográficamente ubicado en el límite de las provincias argentinas del Chaco y Santiago del Estero (latitud -26° a -28° y longitud entre 61° y 63°). De acuerdo a la conformación de las líneas de cráteres formados, tenemos una primera dirección S.O. a N.E., centralizándose en un lugar llamado "Paraje las Víboras", ubicado entre 61̣°39' y 61°41' de longitud oeste y entre 27°36' y 27°37' de latitud, con un meteoro de origen férrico de 33 toneladas de peso y medidas de 2.15 x 2.40 x 2.10 m³. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141873 1987-01-01T00:00:00Z El presente trabajo está basado en observaciones realizadas en el lugar denominado "Campo del Cielo", geográficamente ubicado en el límite de las provincias argentinas del Chaco y Santiago del Estero (latitud -26° a -28° y longitud entre 61° y 63°). De acuerdo a la conformación de las líneas de cráteres formados, tenemos una primera dirección S.O. a N.E., centralizándose en un lugar llamado "Paraje las Víboras", ubicado entre 61̣°39' y 61°41' de longitud oeste y entre 27°36' y 27°37' de latitud, con un meteoro de origen férrico de 33 toneladas de peso y medidas de 2.15 x 2.40 x 2.10 m³. http://sedici.unlp.edu.ar:80/handle/10915/141872 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 Since March 3, 1987 we obtained periodic observations of SN 1987A. We discussed the observational results. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141872 1987-01-01T00:00:00Z Since March 3, 1987 we obtained periodic observations of SN 1987A. We discussed the observational results. http://sedici.unlp.edu.ar:80/handle/10915/141870 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 Polarimetric observations of SN 1987A were obtained with the 80 cm telescope at La Plata Observatory using a polarimeter with a helwave rotating sheet. We also used the 2.15 m telescope at CASLEO and the VATPOL polarimeter. We obtained 30 BVRI observations of linear polarization between February 28 and April 29 and 9 observations in the U filter between April 3 and April 10. The intrinsic polarization of SN 1987A decreased until March 25 when it starts to raise again. This increment is very outstanding in the VRI bands. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141870 1987-01-01T00:00:00Z Polarimetric observations of SN 1987A were obtained with the 80 cm telescope at La Plata Observatory using a polarimeter with a helwave rotating sheet. We also used the 2.15 m telescope at CASLEO and the VATPOL polarimeter. We obtained 30 BVRI observations of linear polarization between February 28 and April 29 and 9 observations in the U filter between April 3 and April 10. The intrinsic polarization of SN 1987A decreased until March 25 when it starts to raise again. This increment is very outstanding in the VRI bands. http://sedici.unlp.edu.ar:80/handle/10915/141868 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 It was speculated (Witten, 1984) about the possibility that quarks (u,d,s) strange matter will be the fundamental level of the hadronic matter. If this is true, it seems possible the existence of transitions of exothermic phases of nuclear matter to strange matter. The conditions reached at the nucleus post-bounce epoch for a supernova of type II should be adequate for this process to take place. Assuming the existence of this transition we present the consequences of an explosion under these conditions. We used a gas at a finite temperature as equation of state for the quarks matter, while for the nuclear matter we used the equation of state for free neutrons as also the model of Bethe-Johnson. We conclude that in both situations the process is possible and it may be the responsible for the type II supernova explosions. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141868 1987-01-01T00:00:00Z It was speculated (Witten, 1984) about the possibility that quarks (u,d,s) strange matter will be the fundamental level of the hadronic matter. If this is true, it seems possible the existence of transitions of exothermic phases of nuclear matter to strange matter. The conditions reached at the nucleus post-bounce epoch for a supernova of type II should be adequate for this process to take place. Assuming the existence of this transition we present the consequences of an explosion under these conditions. We used a gas at a finite temperature as equation of state for the quarks matter, while for the nuclear matter we used the equation of state for free neutrons as also the model of Bethe-Johnson. We conclude that in both situations the process is possible and it may be the responsible for the type II supernova explosions. http://sedici.unlp.edu.ar:80/handle/10915/141685 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 Assuming the existence of a polarization produced by Thompson scattering, as suggested by the observations, a model has been computed for the optically thin layers of SN 1987A. Supposing that the isodensities in this region are oblate ellipsoids, we found the equation that describes the observable polarization as a function of its parameters. If we assumed that the inclination of the axis of symmetry and the eccentricity of the envelope are constant and using a model for the mass ejection, we were able to study the evolution of the size and density of the region as a function of time. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141685 1987-01-01T00:00:00Z Assuming the existence of a polarization produced by Thompson scattering, as suggested by the observations, a model has been computed for the optically thin layers of SN 1987A. Supposing that the isodensities in this region are oblate ellipsoids, we found the equation that describes the observable polarization as a function of its parameters. If we assumed that the inclination of the axis of symmetry and the eccentricity of the envelope are constant and using a model for the mass ejection, we were able to study the evolution of the size and density of the region as a function of time. http://sedici.unlp.edu.ar:80/handle/10915/141682 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 V and B light curves for supernova 1987A are here presented and discussed. Just after the outburst in February 23.120 (UT), the brightening was very fast: approximately 6.2 magnitudes in only 7 hours and 41 minutes; subsequently, changes in brightness slowed down and the SN stayed as long as 130 days brighter than magnitude mᵥ=4.4 (or m_b=5.). The brightening rate at the beginning of the event and the time spent around maximum light are somewhat larger than usual. At maximum brightness SN 1987A reached Mᵥₘₐₓ=-16.1, and M_bmax=-14.7. Typical values for a type II SN being Mᵥₘₐₓ ≃ M_bmax = -17.60, the conclusion is arrived at that SN 1987A was fainter than usual for objects of this class. A comparison with other known supernovae is made. This paper will be published in full elsewhere. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141682 1987-01-01T00:00:00Z V and B light curves for supernova 1987A are here presented and discussed. Just after the outburst in February 23.120 (UT), the brightening was very fast: approximately 6.2 magnitudes in only 7 hours and 41 minutes; subsequently, changes in brightness slowed down and the SN stayed as long as 130 days brighter than magnitude mᵥ=4.4 (or m_b=5.). The brightening rate at the beginning of the event and the time spent around maximum light are somewhat larger than usual. At maximum brightness SN 1987A reached Mᵥₘₐₓ=-16.1, and M_bmax=-14.7. Typical values for a type II SN being Mᵥₘₐₓ ≃ M_bmax = -17.60, the conclusion is arrived at that SN 1987A was fainter than usual for objects of this class. A comparison with other known supernovae is made. This paper will be published in full elsewhere. http://sedici.unlp.edu.ar:80/handle/10915/141681 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 The present work reports the estimation of the energy radiated by SN 1987A since its explosion, a quantity which is of special interest on account of the unusual characteristics of the star's light curve (faint maximum and low magnitude decline). The total energy may be defined as the area under the curve of the intensity I as a function time, where I is obtained from the absolute bolometric magnitude of the object: the contribution from the kinetic energy and that carried away by the neutrinos is explicitly excluded in this calculation. From the outburst until June 27, 1987, the light curve used for the supernova is that given by Milone et al. (1987, this issue); and from then on a lineal decrease of mᵥ with t is applied to evaluate E for two values of the bolometric correction (0.0 and -0.5) and also two different values of the distance to the Large Magellanic Cloud (46 and 52 kpc). SN 1987A has turned out to be an abnormally faint object for its class since the four energy values calculated lie between 6.5x10⁴⁸ erg and 1.3x10⁴⁹ erg, while the value currently accepted as normal (under the same hypothesis presented here) is about 3.6x10⁴⁹ erg. This paper will be published in full length elsewhere. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141681 1987-01-01T00:00:00Z The present work reports the estimation of the energy radiated by SN 1987A since its explosion, a quantity which is of special interest on account of the unusual characteristics of the star's light curve (faint maximum and low magnitude decline). The total energy may be defined as the area under the curve of the intensity I as a function time, where I is obtained from the absolute bolometric magnitude of the object: the contribution from the kinetic energy and that carried away by the neutrinos is explicitly excluded in this calculation. From the outburst until June 27, 1987, the light curve used for the supernova is that given by Milone et al. (1987, this issue); and from then on a lineal decrease of mᵥ with t is applied to evaluate E for two values of the bolometric correction (0.0 and -0.5) and also two different values of the distance to the Large Magellanic Cloud (46 and 52 kpc). SN 1987A has turned out to be an abnormally faint object for its class since the four energy values calculated lie between 6.5x10⁴⁸ erg and 1.3x10⁴⁹ erg, while the value currently accepted as normal (under the same hypothesis presented here) is about 3.6x10⁴⁹ erg. This paper will be published in full length elsewhere. http://sedici.unlp.edu.ar:80/handle/10915/141680 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 A preliminary analysis of the changes in the spectrum of SN 1987A is carried out by means of material collected in the Estación Astrofísica de Bosque Alegre since March 1987. In this first approach to the problem we have used spectra on 103 a-D plates with a dispersion of 123 Å/mm, covering the spectral region between 3800 Å and 6000 Å. The plate resolution is about 2.5 Å. Balmer lines (typical of type II supernovae) are readily identified in SN 1987A and most of the spectral lines show P-Cygni profiles. The changes in the spectrum -such as variations in relative intensity of future shifts- can be easily seen and must be related to changes in the physical conditions of the star's envelope. A remarkable case is that of Hβ line which, moved about 150 Å and 200 Å (absorption and emission, respectively) towards shorter wavelengths by the end of March in about one week's time: this could indicate that the gases ejected became optically thick. The radial velocities determined for different lines are continuously decreasing in absolute value since the outburst, on February. This paper will be published in full length elsewhere. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141680 1987-01-01T00:00:00Z A preliminary analysis of the changes in the spectrum of SN 1987A is carried out by means of material collected in the Estación Astrofísica de Bosque Alegre since March 1987. In this first approach to the problem we have used spectra on 103 a-D plates with a dispersion of 123 Å/mm, covering the spectral region between 3800 Å and 6000 Å. The plate resolution is about 2.5 Å. Balmer lines (typical of type II supernovae) are readily identified in SN 1987A and most of the spectral lines show P-Cygni profiles. The changes in the spectrum -such as variations in relative intensity of future shifts- can be easily seen and must be related to changes in the physical conditions of the star's envelope. A remarkable case is that of Hβ line which, moved about 150 Å and 200 Å (absorption and emission, respectively) towards shorter wavelengths by the end of March in about one week's time: this could indicate that the gases ejected became optically thick. The radial velocities determined for different lines are continuously decreasing in absolute value since the outburst, on February. This paper will be published in full length elsewhere. http://sedici.unlp.edu.ar:80/handle/10915/141603 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 We applied a new numerical technique, developed recently by one of the authors and based on a method found by Zadunaisky, to a classical problem of Celestial Mechanics. The problem consists in the discovery of a massive object whose existence is assumed on the base of systematic deviatiosn form the orbits of known planets. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141603 1987-01-01T00:00:00Z We applied a new numerical technique, developed recently by one of the authors and based on a method found by Zadunaisky, to a classical problem of Celestial Mechanics. The problem consists in the discovery of a massive object whose existence is assumed on the base of systematic deviatiosn form the orbits of known planets. http://sedici.unlp.edu.ar:80/handle/10915/141594 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 We make a model for an outburst occurred in the Halley Comet during March 23-25, 1986. With radio and UV observations we detected an increase in the production rate of gas by a factor of 2.5 in one day. Taking into account the evolution of four bursts in the 1667 MHz line of OH, we proposed a model for the dissociation of this radical. We calculate the photo-chemical lifetime of the OH and H₂O. The lifetimes calculated for the OH in the Halley at 1 A.U. from the Sun, change between 2.3x10⁵ and 4.7x10⁵ sec. for heliocentric radial velocities which range between -27 km/sec and +27 km/sec. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141594 1987-01-01T00:00:00Z We make a model for an outburst occurred in the Halley Comet during March 23-25, 1986. With radio and UV observations we detected an increase in the production rate of gas by a factor of 2.5 in one day. Taking into account the evolution of four bursts in the 1667 MHz line of OH, we proposed a model for the dissociation of this radical. We calculate the photo-chemical lifetime of the OH and H₂O. The lifetimes calculated for the OH in the Halley at 1 A.U. from the Sun, change between 2.3x10⁵ and 4.7x10⁵ sec. for heliocentric radial velocities which range between -27 km/sec and +27 km/sec. http://sedici.unlp.edu.ar:80/handle/10915/141593 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 The motion of asteroids which, together with Jupiter and Saturn, satisfy the commensurability relation n-3n'+2n''=0 (where the mean motions correspond to the asteroid, Jupiter and Saturn, respectively) has been studied. Through a generalization of Wilkens's method possible librators were sought, and five asteroids were found in such a condition. These results were then checked by direct numerical integration of the equations of motion for one hundred thousand years, finding temporary libration in three asteroids. We conclude that this particular triple commensurability affects very significantly the dynamics of these bodies (in some cases, chaotic motion was observed), even though no sign of orbital evolution was found. This paper will be published elsewhere. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141593 1987-01-01T00:00:00Z The motion of asteroids which, together with Jupiter and Saturn, satisfy the commensurability relation n-3n'+2n''=0 (where the mean motions correspond to the asteroid, Jupiter and Saturn, respectively) has been studied. Through a generalization of Wilkens's method possible librators were sought, and five asteroids were found in such a condition. These results were then checked by direct numerical integration of the equations of motion for one hundred thousand years, finding temporary libration in three asteroids. We conclude that this particular triple commensurability affects very significantly the dynamics of these bodies (in some cases, chaotic motion was observed), even though no sign of orbital evolution was found. This paper will be published elsewhere. http://sedici.unlp.edu.ar:80/handle/10915/141591 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 The stability of the Jupiter-Saturn region is analyzed, in the context of the four body problem, by direct numerical integration of the equations of motion of a group of fictitious asteroids. The results indicate that the region is highly unstable with the exception of two resonance points: the 3/2 and the 1/1 Saturn commensurabilities. Two ejection mechanisms were found: one extremely fast (∼ 10² yrs.) produced by direct close encounters with the planets, and in which the orbits of the bodies turn hyperbolic. The other mechanism (∼ 10⁴ yrs.), is due to the existence of regions of chaotic motion formed by resonance relations. In this case, the asteroids suffer secular changes in the eccentricity and, after close encounters with one of the perturbers, finally escapes. The behaviour of the stable points of the region, is totally different. In the S:3/2 resonance, the results show a small region of stability, in which the motion of the bodies is quasi-periodic. The same thing can be said for the S:1/1 resonance, in which the flux of asteroids to the commensurability and the following regularization of their orbits seems to support the idea of possible Troyans associated with Saturn. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141591 1987-01-01T00:00:00Z The stability of the Jupiter-Saturn region is analyzed, in the context of the four body problem, by direct numerical integration of the equations of motion of a group of fictitious asteroids. The results indicate that the region is highly unstable with the exception of two resonance points: the 3/2 and the 1/1 Saturn commensurabilities. Two ejection mechanisms were found: one extremely fast (∼ 10² yrs.) produced by direct close encounters with the planets, and in which the orbits of the bodies turn hyperbolic. The other mechanism (∼ 10⁴ yrs.), is due to the existence of regions of chaotic motion formed by resonance relations. In this case, the asteroids suffer secular changes in the eccentricity and, after close encounters with one of the perturbers, finally escapes. The behaviour of the stable points of the region, is totally different. In the S:3/2 resonance, the results show a small region of stability, in which the motion of the bodies is quasi-periodic. The same thing can be said for the S:1/1 resonance, in which the flux of asteroids to the commensurability and the following regularization of their orbits seems to support the idea of possible Troyans associated with Saturn. http://sedici.unlp.edu.ar:80/handle/10915/141589 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 The asteroids 23 Thalia, 40 Harmonia, 45 Eugenia, 54 Alexandra, 135 Hertha and 192 Nausikea have been studied by means of photoelectric photometry with the purpose of determining their rotation periods, pole orientation and shapes. The light curves of 23 Thalia and 40 Harmonia are shown. A new period is found for 40 Harmonia. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141589 1987-01-01T00:00:00Z The asteroids 23 Thalia, 40 Harmonia, 45 Eugenia, 54 Alexandra, 135 Hertha and 192 Nausikea have been studied by means of photoelectric photometry with the purpose of determining their rotation periods, pole orientation and shapes. The light curves of 23 Thalia and 40 Harmonia are shown. A new period is found for 40 Harmonia. http://sedici.unlp.edu.ar:80/handle/10915/141516 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 The formation conditions of the binary systems Pluto-Charon in the early solar nebula are analyzed with special emphasis on its high spin angular momentum, which would lead the system beyond the limit of rotational stability in the ideal case that both bodies coalesced into a single body. Among several possible scenarios of formation, the acquisition of such a high content angular momentum is explained on the basis of a collision of two protoplanets of comparable masses in an intermediate stage of the planetary formation, before Neptune perturbed Pluto on a highly eccentric orbit. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141516 1987-01-01T00:00:00Z The formation conditions of the binary systems Pluto-Charon in the early solar nebula are analyzed with special emphasis on its high spin angular momentum, which would lead the system beyond the limit of rotational stability in the ideal case that both bodies coalesced into a single body. Among several possible scenarios of formation, the acquisition of such a high content angular momentum is explained on the basis of a collision of two protoplanets of comparable masses in an intermediate stage of the planetary formation, before Neptune perturbed Pluto on a highly eccentric orbit. http://sedici.unlp.edu.ar:80/handle/10915/141512 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 A study of thermal decoupling in short period near contact binaries is presented. Statistics of well-observed W UMa systems (now including data of EB-type light curve objects) characterize completely A- and W- type objects. W-type systems show a good linear correlation in the thermal decoupling vs. spectral type diagram. The same correlation is valid for the lower border of the distribution of A-type systems, otherwise scattered in an area of large thermal decoupling. These empirical facts are discussed in terms of contact on near contact configurations. A complete version of this paper will be published in Publication Astronomical Soc. of the Pacific. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141512 1987-01-01T00:00:00Z A study of thermal decoupling in short period near contact binaries is presented. Statistics of well-observed W UMa systems (now including data of EB-type light curve objects) characterize completely A- and W- type objects. W-type systems show a good linear correlation in the thermal decoupling vs. spectral type diagram. The same correlation is valid for the lower border of the distribution of A-type systems, otherwise scattered in an area of large thermal decoupling. These empirical facts are discussed in terms of contact on near contact configurations. A complete version of this paper will be published in Publication Astronomical Soc. of the Pacific. http://sedici.unlp.edu.ar:80/handle/10915/141511 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 The eclipsing binary RU Eri (P=0.63 d; V=9.35 m) was observed spectroscopically from CTIO with a dispersion of 43 Å/mm in the blue and 86 Å/mm in Hα. We analyzed the radial velocity plots and we derived the orbital elements for the primary component. A model for the system is proposed. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141511 1987-01-01T00:00:00Z The eclipsing binary RU Eri (P=0.63 d; V=9.35 m) was observed spectroscopically from CTIO with a dispersion of 43 Å/mm in the blue and 86 Å/mm in Hα. We analyzed the radial velocity plots and we derived the orbital elements for the primary component. A model for the system is proposed. http://sedici.unlp.edu.ar:80/handle/10915/141450 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 GY Tel is a short period (0.446 d) eclipsing binary system of 12th magnitude showing a large difference(0.85 mag) in the depths of minima. The first UBV observations obtained at Bosque Alegre (Córdoba) and at CASLEO (San Juan) are presented. The light curves are covered by 400 observations. Eight photoelectric times of minima were determined and a period study was carried out. GY Tel is another near contact binary system with large thermal decoupling of special interest for the theories of evolution of near contact systems. A complete version of this paper will be published in Pub. Astron. Soc. of the Pacific. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141450 1987-01-01T00:00:00Z GY Tel is a short period (0.446 d) eclipsing binary system of 12th magnitude showing a large difference(0.85 mag) in the depths of minima. The first UBV observations obtained at Bosque Alegre (Córdoba) and at CASLEO (San Juan) are presented. The light curves are covered by 400 observations. Eight photoelectric times of minima were determined and a period study was carried out. GY Tel is another near contact binary system with large thermal decoupling of special interest for the theories of evolution of near contact systems. A complete version of this paper will be published in Pub. Astron. Soc. of the Pacific. http://sedici.unlp.edu.ar:80/handle/10915/141449 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 The absolute proper motion of the primary component of this pair is derived on the basis of all available photographic and meridian observations, spanning over 55 years. The relative trajectory is then computed from all existing differential measurements, and different criteria were used to show that the pair is optical. An ephemeris is presented for the interval 1988-2000. The proper motion for the secondary component is obtained by combining that of the primary with the relative motion, achieving a much higher precision than that allowed by the very few absolute observations of the secondary alone. Both proper motions are finally compared with other determinations. The complete version of this work will be published elsewhere. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141449 1987-01-01T00:00:00Z The absolute proper motion of the primary component of this pair is derived on the basis of all available photographic and meridian observations, spanning over 55 years. The relative trajectory is then computed from all existing differential measurements, and different criteria were used to show that the pair is optical. An ephemeris is presented for the interval 1988-2000. The proper motion for the secondary component is obtained by combining that of the primary with the relative motion, achieving a much higher precision than that allowed by the very few absolute observations of the secondary alone. Both proper motions are finally compared with other determinations. The complete version of this work will be published elsewhere. http://sedici.unlp.edu.ar:80/handle/10915/141448 Comunicacion Boletín de la Asociación Argentina de Astronomía; no. 33 New IUE images of the close binary β Persei in the phase interval 0.6P-0.8P were analysed in order to confirm or rectify conclusions previously suggested concerning the region where C IV lines are formed. Based on IUE observations taken with high dispersion and small aperture, Sahade and Hernández (1985) concluded that the resonance lines of Si IV would originate in regions near the B8 V component. Instead, the C IV behaviour of velocity-wise in phases 0.65P-0.78P would seem to suggest that this ion would form in a region of the extended envelope that surrounds the whole system. Our recent IUE images, taken with high dispersion and large aperture that cover precisely the phase interval that was not well covered with the first set of observations, show that, in fact, the C IV resonance doublet behaves in the same way as the Si IV. Therefore, Si IV and C IV are formed in the same region of the envelope that surrounds the B8 V component and there is not, indeed, evidence for the existence of more than one high temperature region in the system of Per, such as it had been thought on the basis of former material. On each spectrum the C IV lines are weaker than Si IV. As the available material is not homogeneous, we can not determine variations, with phase in the line profiles and intensities. A new set of observations covering all the orbital cycle ought to be secured to be able to explain the different behaviour of the intensities. Thu, 01 Jan 1987 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/141448 1987-01-01T00:00:00Z New IUE images of the close binary β Persei in the phase interval 0.6P-0.8P were analysed in order to confirm or rectify conclusions previously suggested concerning the region where C IV lines are formed. Based on IUE observations taken with high dispersion and small aperture, Sahade and Hernández (1985) concluded that the resonance lines of Si IV would originate in regions near the B8 V component. Instead, the C IV behaviour of velocity-wise in phases 0.65P-0.78P would seem to suggest that this ion would form in a region of the extended envelope that surrounds the whole system. Our recent IUE images, taken with high dispersion and large aperture that cover precisely the phase interval that was not well covered with the first set of observations, show that, in fact, the C IV resonance doublet behaves in the same way as the Si IV. Therefore, Si IV and C IV are formed in the same region of the envelope that surrounds the B8 V component and there is not, indeed, evidence for the existence of more than one high temperature region in the system of Per, such as it had been thought on the basis of former material. On each spectrum the C IV lines are weaker than Si IV. As the available material is not homogeneous, we can not determine variations, with phase in the line profiles and intensities. A new set of observations covering all the orbital cycle ought to be secured to be able to explain the different behaviour of the intensities.