|
|||||
|
|
High-speed knots in the hourglass-shaped planetary nebula Hubble 12 |
|
| Authors: | N M H Vaytet A P Rushton M Lloyd J A López J Meaburn T J O'Brien D L Mitchell D Pollacco |
| Institution: | Service d'Astrophysique, CEA/DSM/DAPNIA/SAp, Centre d'Études de Saclay, L'Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France;Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL;Instituto de Astronomía, Universidad Nacional Autnoma de México, Apartado Postal 877, 22800 Ensenada, B.C., México;Department of Pure and Applied Physics, Queen's University Belfast, Belfast BT7 1NN |
| Abstract: | We present a detailed kinematical analysis of the young compact hourglass-shaped planetary nebula Hb 12. We performed optical imaging and long-slit spectroscopy of Hb 12 using the Manchester echelle spectrometer with the 2.1-m San Pedro Mártir telescope. We reveal, for the first time, the presence of end caps (or knots) aligned with the bipolar lobes of the planetary nebula shell in a deep N ii ]λ6584 image of Hb 12. We measured from our spectroscopy radial velocities of ∼120 km s We have derived the inclination angle of the hourglass-shaped nebular shell to be ∼65° to the line of sight. It has been suggested that Hb 12's central star system is an eclipsing binary which would imply a binary inclination of at least 80°. However, if the central binary has been the major shaping influence on the nebula, then both nebula and binary would be expected to share a common inclination angle. Finally, we report the discovery of high-velocity knots with Hubble-type velocities, close to the core of Hb 12, observed in Hα and oriented in the same direction as the end caps. Very different velocities and kinematical ages were calculated for the outer and inner knots showing that they may originate from different outburst events. |
| Keywords: | circumstellar matter stars: kinematics stars: mass-loss ISM: jets and outflows planetary nebulae: individual: Hb 12 |