Interacting planetary nebulae

II. Galactic population and interaction models

¹ Astronomy Dept, Faculty of Science, King Abdulaziz University, 21589 Jeddah, Saudi Arabia
e-mail: afmali@kau.edu.sa
² Department of Astronomy, Faculty of Science, Cairo University, 12613 Cairo, Egypt
³ National Research Institute of Astronomy and Geophysics, 11421 Helwan, Egypt
⁴ Instituto de Astronomía y Meteorología, Departamento de Física, CUCEL, Universidad de Guadalajara, Av. Vallarta 2602, CP 44130 Guadalajara, jal., México

Received: 30 April 2013
Accepted: 16 July 2013

Abstract

In the present paper, we discuss the classification of planetary nebulae that show interaction with the interstellar medium in terms of Galactic population. Furthermore, we investigate the case of interaction of each object in the framework of the isothermal and adiabatic shock models and we derive the mean critical, leading, and stopping densities of the nebulae located in the Galactic thin and thick disks. A sample of 34 objects with available proper motions, radial velocities, and reliable distances in the literature was used for these purposes. The results show that 16 and 10 objects are classified as Galactic thin-disk and thick-disk populations, respectively. Seven objects are classified as probable thin-disk populations, and one as a probable thick-disk population. The flow and cooling time of the post-shock nebular gas are derived and the cooling/flow time ratio shows a linear correlation versus the Galactic height of the interacting planetary nebulae. The results reveal that there is a tendency for the interacting planetary nebulae belonging to the thin disk to follow an isothermal shock model, whilst those belonging to the thick disk to follow an adiabatic shock model.