Bibcode
DOI
Guerrero, M. A.; Manchado, A.; Serra-Ricart, M.
Bibliographical reference
Astrophysical Journal v.456, p.651
Advertised on:
1
1996
Citations
21
Refereed citations
19
Description
A comprehensive study of the planetary nebula K4-55 is presented. In
addition to CCD narrowband images, spatially resolved low-dispersion and
high-resolution spectra were obtained. This has allowed the different
morphological features in the images to be connected with the kinematics
and with the physical information, leading to the establishment of the
complex nebular structure.
K4-55 is a new multiple-shell planetary nebula displaying three
different parts: a faint halo that extends up to 2' from the main
nebula; an outer part revealed by the kinematical study as a pole-on
bipolar structure; and an inner, bright ring. The bipolar structure is
expanding at ˜100 km s-1 at the poles, while the halo
has Vexp ≲ 8.6 km s-1. The inner ring
exhibits intriguing kinematics, indicating a likely presence of
rotation. Abundance variations are found throughout the nebula, with a
N/O abundance ratio enhancement in the [N II]-bright central ring,
whereas the extended halo presents a much smaller ratio. The N/O ratio
reported is among the highest ever found in planetary nebulae. The outer
halo is consistent with the asymptotic giant branch wind, whereas the
inner nebula was formed during a later mass-loss phase.