@article{PenaHamannRuiz2003,
  author    = {Pena, M. and Hamann, Wolf-Rainer and Ruiz, M. T.},
  title     = {The LMC planetary nebula N66 revisited. Nebular kinematics and stellar models},
  isbn      = {1-583-81148-6},
  year      = {2003},
  language  = {en}
}
@article{PenaPeimbertHamannetal.2004,
  author    = {Pena, M and Peimbert, A. and Hamann, Wolf-Rainer and Ruiz, M. T. and Peimbert, M.},
  title     = {The extraordinary planetary nebula N66 in the LMC},
  isbn      = {3-12-283174-0},
  year      = {2004},
  abstract  = {Morphology of the planetary nebula LMC-N66 (ionized by a [WN] star) indicates that the nebula is a multipolar object with a very narrow waist. It shows several jets, knots and filaments in opposite directions from the central star. A couple of twisted long filaments could be interpreted as due to point-symmetric type ejection. If such is the case, the progenitor would be a binary precessing system. High resolution spectroscopy shows that most of the material is approaching or receding from the star. However the line profiles are very complex, showing several components at different velocities. Our high resolution spectroscopic data show that the different structures (knots, filaments, ...) present different radial velocities spreading from 240 to more than 400 km/s. The system velocity is 300 km/s. There are high velocity knots located to the north of the central star, moving at more than 100 km/s relative to the system velocity.},
  language  = {en}
}
@phdthesis{HamannPenaGraefeneretal.2003,
  author    = {Hamann, Wolf-Rainer and Pena, M. and Gr{\"a}fener, G{\"o}tz and Ruiz, M. T.},
  title     = {The central star of the planetary nebula N66 in the Large Magellanic Cloud : a detailed analysis of its dramatic evolution 1983 - 2000},
  issn      = {0004-6361},
  year      = {2003},
  language  = {en}
}
@article{PenaHamannKoesterkeetal.1997,
  author    = {Pena, M. and Hamann, Wolf-Rainer and Koesterke, Lars and Maza, J. and Mendez, R. H. and Peimbert, M. and Ruiz, M. T. and Torres-Peimbert, S.},
  title     = {Spectrophotometric data of the central star of the large magellanic cloud planetary nebula N66. Quantitative analysis of its WN type spectrum},
  year      = {1997},
  language  = {en}
}
@article{PenaHamannKoesterkeetal.1997,
  author    = {Pena, M. and Hamann, Wolf-Rainer and Koesterke, Lars and Maza, J. and Mendez, R. H. and Peimbert, M. and Ruiz, M. T. and Torres-Peimbert, S.},
  title     = {HST spectrophotometric data of the central star of the planetary nebula LMC-N66},
  year      = {1997},
  language  = {en}
}
@article{PenaHamannRuizetal.2004,
  author    = {Pena, M. and Hamann, Wolf-Rainer and Ruiz, M. T. and Peimbert, A. and Peimbert, M.},
  title     = {A high resolution spectroscopic study of the extraordinary planetary nebula LMC-N66},
  year      = {2004},
  abstract  = {The planetary nebula N66 in the Large Magellanic Cloud is an extraordinary object, as it is the only confirmed PN where the central star is a Wolf-Rayet star of the nitrogen sequence, i.e. of type [WN]. Moreover, the star showed a dramatic brightness outburst in 1993-1994. In a previous paper (Hamann et al. 2003) we analyzed the changing stellar spectra and found evidence that the central star is most likely a binary system where a white dwarf presently accretes matter from a non-degenerate companion at a high rate. Thus the object is a candidate for a future type Ia supernova in our cosmic neighborhood. In the present paper we analyze the morphology and kinematics of the nebula, using images and high-resolution spectra obtained with the Hubble Space Telescope (HST) and the Very Large Telescope (ESO-VLT). The object presents a complex multipolar structure, dominated by very bright lobes located at both sides of the central star and separated by a narrow waist. In addition there is a pair of very extended and twisted loops, also pointing in opposite directions; their symmetry axis and collimation angle differs from those of the bright lobes. High resolution spectroscopy reveals two main velocity components, "approaching" material at an average heliocentric radial velocity Of V-rad = 248 30 km s(-1) and similarly bright "receding" material at V-rad = 331 +/- 25 km s(-1). A systemic velocity of about 300 km s(-1) is derived. Opposite lobes and loops possess opposite velocities. Furthermore there are knots and filaments of complex structure and kinematics. Close to the central star, nebular gas is found, receding at very high velocity (125 km s(-1) relative to the system). The morphology and kinematics of LMC-N66 can be explained as the result of episodic bipolar ejections with changing axis. The bipolar structures could have been produced by collimated streams ejected from a precessing central source. We suggest that the precession could have been produced by an external torque, possibly due to a binary companion. Young, fast-moving nebular knots close to the star appear slightly He- and N-richer than the main body of the nebula, but are still hydrogen-rich in contrast to the helium-dominated atmosphere of the [WN]- type central star. In the binary scenario, this nebular matter must have been accreted from the non-degenerate companion and re-ejected before it was fully burnt},
  language  = {en}
}