A re-analysis of the Am star τ U Ma is carried out using new determinations of effective temperature and gravity. The abundances agree in general except a constant factor with those found by Greenstein. The existence of certain heavy elements found in the most cold Ap stars is investigated.Asociación Argentina de Astronomí

López-García, Z.

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ASTROFISICA TEORICACOMUNICACIONESThe mees function in spectroscopfc binarlesC. Jaschek and O. FerrerObservatorio Astronómico, La PlataAbstract: The distribution of the mass function of bright spectros- copic binaries is studied for systems with dwarf and with giant primaries. It is found that the distribution is very similar in both cases.Assuming that the inclination has a random distribution and postulating different distribution functions for the mass ratio, it is found that the distribution of the mass function depends only weakly upon the distribution function of the mass ratio.Apparently a distribution law f(/0 = —7/3 reproduces well the observed statistics, provided that fi varíes between 1 and 0,25. These results are in agreement with those found by C. Jaschek in Publ. Obs. Geneve, N*  24 (1971).The paper in full will be published elsewhere.Critícal revisión of the methods for the derivation of the luminosity functionJ. C. Muzzio *Observatorio Astronómico, La PlataAbstract: Different methods employed for the derivation of the luminosity function in the solar neighbourhood are reviewed. It is shown that most of these methods introduce systematic errors in the results. It is shown that, with certain improvements, van Rhijn’s method is the best one.* Becario interno del Consejo Nacional de Investigaciones Cien­tíficas y Técnicas.The luminosity function in the solar neighbourhoodJ. C. Muzzio *Observatorio Astronómico, La PlataAbstract: van Rhijn’s method is used to derive the luminosity function in the solar neighbourhood from large proper motion stars. The valúes obtained are smaller than the currently accepted ones; for MB< 9, the factor is of the order of two. It is shown that these differences arise from the systematic errors of other me­thods, specially for non-inclusion of the correction for the errors of the parallaxes. The luminosity function has some irregularities, not previously found because of smoothing. A secondary máximum near MB =11, particularly, seems to be a real feature.* Becario interno del Consejo Nacional de Investigaciones Cien­tíficas y Técnicas. ,Acerca de los parámetros de cúmulos abiertos y nubes galácticasC. J. LavagninoObservatorio Astronómico, La PlataResumen: El problema de la relación entre nubes y estrellas es analizado según las relaciones entre el núcleo y el tamaño de los cúmulos abiertos.A Re-Analysis of t U MaZ. López GarcíaObservatorio Astronómico, La Plata y CONICET, Buenos AiresAbstract: A re-analysis of the Am star xU Ma is carried out using new determinations of effective temperature and gravity. The abundances agree in general except a constant factor with those found by Greenstein. The existence of certain heavy elements founded in the most coid Ap stars is investigated.INFORME DE TRABAJOEl diagrama magnitud - diámetro de las asociaciones de estrellas O y B y de los cúmulos estelares globulares y abiertosH. WlLKENSObservatorio Astronómico, La PlataEn el año 1960 el autor publicó por primera vez un diagrama que representa la dependencia de los diámetros de los cúmulos globulares de sus magnitudes integrales. Los datos cbservacionales directos, es decir, por un lado la magnitud integral aparente, por el otro lado el diámetro aparente ya nos dan una imaginación exacta del resultado final. Este realmente es una línea recta. Desde el punto de vista puramente matemático, este resultado no sufre12 Bol. N9 17 - Asoc. Arg. de Astr.

A re-analysis of τ U Ma

http://sedici.unlp.edu.ar/bitstream/handle/10915/98707/Resumen__1_p._.pdf?sequence=1

A re-analysis of τ U Ma

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