W. J. Maciel, G. R. Keller, and R. D. D. Costa
Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão 1226, CEP 05508–900, São Paulo SP, Brazil (maciel@astro.iag.usp.br, graziela@astro.iag.usp.br, roberto@astro.iag.usp.br)
Received 2007 October 29
Accepted 2008 February 20
RESUMEN
]]> Investigaciones recientes de las estrellas centrales de nebulosas planetarias (CSPN) indican que las masas basadas en modelos de atmósferas pueden ser mucho mayores que las masas derivadas de las relaciones teóricas masa–luminosidad. También, la dispersión en la relación entre el momento modificado del viento y la luminosidad depende de la dispersión de las masas de las CSPN, y es mayor que la observada en estrellas calientes masivas. Como las características del viento dependen probablemente de la metalicidad, analizamos los efectos en el momento modificado del viento considerando la dispersión en esta cantidad causada por la metalicidad estelar. Nuestras masas para las CSPN están basadas en una relación entre la masa del núcleo y las abundacias nebulares. Concluimos que estas masas concuerdan con la distribución de masas conocida, tanto para CSPN como para enanas blancas, y que la dispersión en el momento modificado del viento puede ser explicada por las variaciones de metalicidad observadas.
ABSTRACT
Recent investigations on the central stars of planetary nebulae (CSPN) indicate that the masses based on model atmospheres can be much larger than the masses derived from theoretical mass–luminosity relations. Also, the dispersion in the relation between the modified wind momentum and the luminosity depends on the mass spread of the CSPN, and is larger than observed in massive hot stars. Since the wind characteristics probably depend on the metallicity, we analyze the effects on the modified wind momentum by considering the dispersion in this quantity caused by the stellar metallicity. Our CSPN masses are based on a relation between the core mass and the nebular abundances. We conclude that these masses agree with the known mass distribution both for CSPN and white dwarfs, and that the spread in the modified wind momentum can be explained by the observed metallicity variations.
Key Words: planetary nebulae: general — stars: mass loss — stars: winds, outflows
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Acknowledgement
This work was partly supported by FAPESP and CNPq.
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