Volume 456, Number 2, September III 2006
|Page(s)||591 - 597|
|Section||Interstellar and circumstellar matter|
|Published online||31 August 2006|
IC 5217 as a double-shell, point-symmetric planetary nebula with a very narrow waist
Instituto de Astrofísica de Andalucía (CSIC), Camino Bajo de Huétor 50, 18008 Granada, Spain e-mail: [lfm;sayala]@iaa.es
2 Instituto de Astronomía, UNAM, Ap. Postal 877, 22800 Ensenada BC, Mexico e-mail: [vazquez;sayala;fguillen]@astrosen.unam.mx
Accepted: 9 June 2006
Aims.Identification of the structural components and analysis of the internal kinematics in the planetary nebula IC 5217.
Methods.Narrow-band images and high resolution long-slit spectra in the Hα, [N ii] and [O iii] emission lines, and VLA 6 cm continuum data.
Results.IC 5217 is composed of a very bright equatorial ring, open bipolar lobes, off-axis point-symmetric features, on-axis distant faint regions, and an off-axis very elongated bipolar structure. The ring, open lobes, point-symmetric features and distant faint regions appear as elements of a single point-symmetric bipolar shell with a very narrow waist. This shell presents an axis ratio of ~37 and an aspect ratio of ~5. The 6 cm data show that the ring is an extremely flat disk with a central hole. Expansion velocity in the ring ranges from ≤10 km s-1 in He ii up to 27 km s-1 in [N ii], whereas a velocity of ~460 km s-1 is estimated for the polar regions of the bipolar shell. Strong acceleration of the outer regions of the ring is observed. The elongated bipolar structure probably represents a highly collimated (aspect ratio ~12), high velocity cylindrical-like shell. A collimated agent (wind or jet) would account for the shaping of the bipolar shell if this agent has operated in the direction perpendicular to the equatorial disk. The point-symmetric features and cylindrical shell are probably related to collimated ejections but that occurred when the basic nebular shape had already been established.
Key words: planetary nebulae: individual: IC 5217 / ISM: jets and outflows
© ESO, 2006
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