Bibcode
Lopez-Martin, L.; Raga, A. C.
Referencia bibliográfica
"IX Latin American Regional IAU Meeting, "Focal Points in Latin American Astronomy", held in Tonantzintla, Mexico, Nov 9-13, 1998, Eds: Aguilar, A.; Carraminana, A.; to be printed in Revista Mexicana de Astronomia y Astrofisica Serie de Conferencias."
Fecha de publicación:
11
1998
Número de citas
0
Número de citas referidas
0
Descripción
The Cometary Knots in the Helix Nebula have shown themselves to be
formed of a head which is a photoionized surface, optically thick to
Lyman continuum radiation, on the central star facing sides of neutral
clumps and a cometary tails photionized by the diffuse radiation field.
In this study we will present the results of a photoionization model of
the heads and the tails using the observations made with the NASA/ESA
Hubble Space Telescope, obtained from the data archive at the Space
Telescope Science Institute. We obtain a value of the lumionsity of the
central star and we find that there is no correlation between the size
of the knot and the distance of the central star. We also verify the
validity of the "on the spot" approximation usually assumed in planetary
nebulae.