C. Morisset1 and G. Stasinska2
1 Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70–264, 04510 México, D. F., México (morisset@astroscu.unam.mx).
2 LUTH, Observatoire de Paris, CNRS, Université Paris Diderot; Place Jules Janssen, 92190 Meudon, France (grazyna.stasinska@obspm.fr)
Received 2007 November 08
Accepted 2008 January 22
]]> RESUMEN
Hemos construido una malla de modelos de fotoionización para nebulosas planetarias esféricas, elípticas y bipolares. Suponiendo distintos campos de velocidades, hemos calculado los perfiles de línea que corresponden a distintas orientaciones, tamaños y posiciones de la rendija. Este atlas está destinado tanto para propósitos didácticos como para ayudar en la interpretación de los datos en nebulosas reales. Como una aplicación, mostramos que los perfiles de línea con frecuencia están degenerados, y que para recuperar de las observaciones la geometría y el campo de velocidades es necesario usar líneas de iones de masas y potenciales de ionización distintos. También mostramos que la manera empírica de medir las velocidades de expansión ponderadas por la masa a partir de los anchos de línea es bastante exacta si se considera la HWHM. Para las nebulosas lejanas, totalmente cubiertas por la rendija, la geometría y la orientación desconocidas no alteran estadísticamente las velocidades medidas. El atlas está disponible en la red. El paquete Cloudy3D y la herramienta asociada a él, VISNEB, pueden solicitarse a los autores.
ABSTRACT
We have constructed a grid of photoionization models of spherical, elliptical and bipolar planetary nebulae. Assuming different velocity fields, we have computed line profiles corresponding to different orientations, slit sizes and positions. The atlas is meant both for didactic purposes and for the interpretation of data on real nebulae. As an application, we have shown that line profiles are often degenerate, and that recovering the geometry and velocity field from observations requires lines from ions with different masses and different ionization potentials. We have also shown that the empirical way to measure mass–weighted expansion velocities from observed line widths is reasonably accurate if considering the HWHM. For distant nebulae, entirely covered by the slit, the unknown geometry and orientation do not alter the measured velocities statistically. The atlas is freely accessible from internet. The Cloudy3D suite and the associated VISNEB tool are available on request.
Key Words: line: profiles — methods: numerical — planetary nebulae: general — turbulence
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Acknowledgments
]]> We are grateful to Gary Ferland for having made public the source of the code Cloudy on which C3D is based. We thanks our referee, Franco Sabbadin, for detecting a numerical error in a previous version of the atlas and for pointing out the effect of fine structure line splitting. The computations were carried out on a AMD–64bit computer financed by grant PAPIIT IX125304 from DGAPA (Universidad Nacional Autónoma de México). C. M. is partly supported by grants Conacyt–49737 and PAPIIT–IN115807 (Mexico). G.S. is grateful to the Instituto de Astronomía, Universidad Nacional Autónoma de México, for hospitality and financial support (grant Conacyt–49737 and DGAPA IN–118405).
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