Observaciones de nebulosas planetarias australes – I

Line identification and data on line intensities are provided from medium-dispersion plates secured at Bosque Alegre with the nebular spectrograph and Carnegie image tube attached to the 154-cm telescope. The results are to be published elsewhere.Asociación Argentina de Astronomí

Comentarios sobre 272 +12̣°1, 292+1°1, 320 – 17°1

Comments are made on the following planetaries: 272 + 12°1: the material available permits us to pose some doubts as to the absence of relation between the planetary and the central star. 292 +1° 1: a study of this object, which presents peculiarities in the expansion velocity, will be published elsewhere. 328 – 17° 1: this object must be excluded from the lists of planetaries. It has been previously studied as a dwarf galaxy by M. Pastoriza (La Galaxia Peculiar IC 4662, Boletín de la Asoc. Argentina de Astronomía, N9 15, pág. 1).Asociación Argentina de Astronomí

Comentarios sobre 272 +12̣°1, 292+1°1, 320 – 17°1

Comments are made on the following planetaries: 272 + 12°1: the material available permits us to pose some doubts as to the absence of relation between the planetary and the central star. 292 +1° 1: a study of this object, which presents peculiarities in the expansion velocity, will be published elsewhere. 328 – 17° 1: this object must be excluded from the lists of planetaries. It has been previously studied as a dwarf galaxy by M. Pastoriza (La Galaxia Peculiar IC 4662, Boletín de la Asoc. Argentina de Astronomía, N9 15, pág. 1).Asociación Argentina de Astronomí

Observaciones de nebulosas planetarias australes – I

Line identification and data on line intensities are provided from medium-dispersion plates secured at Bosque Alegre with the nebular spectrograph and Carnegie image tube attached to the 154-cm telescope. The results are to be published elsewhere.Asociación Argentina de Astronomí

Comentarios sobre 272 +12̣°1, 292+1°1, 320 – 17°1

Comments are made on the following planetaries: 272 + 12°1: the material available permits us to pose some doubts as to the absence of relation between the planetary and the central star. 292 +1° 1: a study of this object, which presents peculiarities in the expansion velocity, will be published elsewhere. 328 – 17° 1: this object must be excluded from the lists of planetaries. It has been previously studied as a dwarf galaxy by M. Pastoriza (La Galaxia Peculiar IC 4662, Boletín de la Asoc. Argentina de Astronomía, N9 15, pág. 1).Asociación Argentina de Astronomí

Observaciones de nebulosas planetarias australes – I

Line identification and data on line intensities are provided from medium-dispersion plates secured at Bosque Alegre with the nebular spectrograph and Carnegie image tube attached to the 154-cm telescope. The results are to be published elsewhere.Asociación Argentina de Astronomí

Observaciones fotométricas y espectroscópicas simultáneas de la estrella central de IC418

Las variaciones de brillo y velocidad radial que se observan en la estrella central de la nebulosa planetaria IC 418 no se pueden atribuir a movimiento orbital en un sistema binario ni a pulsaciones, sean radiales o no. Aparentemente, la única alternativa que queda es atribuirlas a fluctuaciones en la tasa de pérdida de masa, con una escala de tiempo del orden de pocas horas.Asociación Argentina de Astronomí

HD 94546, un sistema múltiple?

HD 94546 es un sistema binario que espectroscópicamente aparece compuesto por una WN4+O. Niemela (1980) determinó la órbita preliminar del mismo. Con el objeto de mejorar los parámetros orbitales de HD 94546 se obtuvieron 46 espectrogramas adicionales, entre 1981 y 1984, en el Observatorio Interamericano de Cerro Tololo con el telescopio de 1 m. El análisis de las variaciones de velocidad radial de las líneas de emisión de la estrella WN y de las absorciones confirma la existencia de un período de 4,385 días y muestra que la velocidad del centro de masa del sistema varía de época en época de observación, sugiriendo que se trata de un sistema múltiple. Se analizan los elementos orbitales de este sistema.Asociación Argentina de Astronomí

The Planetary Nebula Luminosity Function at the Dawn of Gaia

The [O III] 5007 Planetary Nebula Luminosity Function (PNLF) is an excellent extragalactic standard candle. In theory, the PNLF method should not work at all, since the luminosities of the brightest planetary nebulae (PNe) should be highly sensitive to the age of their host stellar population. Yet the method appears robust, as it consistently produces < 10% distances to galaxies of all Hubble types, from the earliest ellipticals to the latest-type spirals and irregulars. It is therefore uniquely suited for cross-checking the results of other techniques and finding small offsets between the Population I and Population II distance ladders. We review the calibration of the method and show that the zero points provided by Cepheids and the Tip of the Red Giant Branch are in excellent agreement. We then compare the results of the PNLF with those from Surface Brightness Fluctuation measurements, and show that, although both techniques agree in a relative sense, the latter method yields distances that are ~15% larger than those from the PNLF. We trace this discrepancy back to the calibration galaxies and argue that, due to a small systematic error associated with internal reddening, the true distance scale likely falls between the extremes of the two methods. We also demonstrate how PNLF measurements in the early-type galaxies that have hosted Type Ia supernovae can help calibrate the SN Ia maximum magnitude-rate of decline relation. Finally, we discuss how the results from space missions such as Kepler and Gaia can help our understanding of the PNLF phenomenon and improve our knowledge of the physics of local planetary nebulae.Comment: 12 pages, invited review at the conference "The Fundamental Cosmic Distance Scale: State of the Art and Gaia Perspective", to appear in Astrophysics and Space Scienc

Probing the Environment with Galaxy Dynamics

I present various projects to study the halo dynamics of elliptical galaxies. This allows one to study the outer mass and orbital distributions of ellipticals in different environments, and the inner distributions of groups and clusters themselves.Comment: 5 pages, 2 figs, to appear in Proc. ESO Workshop, Groups of Galaxies in the Nearby Universe (5-9 Dec 2005), eds. I. Saviane, V. Ivanov & J. Borissova (Springer-Verlag