Deciphering the bipolar planetary nebula Abell 14 with 3D ionization and morphological studies
Abstract
Abell 14 is a poorly studied object despite being considered a born-again planetary nebula. We performed a detailed study of its 3D morphology and ionization structure using the SHAPE and MOCASSIN codes. We found that Abell 14 is a highly evolved, bipolar nebula with a kinematical age of ∼19 400 yr for a distance of 4 kpc. The high He abundance, and N/O ratio indicate a progenitor of 5 M⊙ that has experienced the third dredge-up and hot bottom burning phases. The stellar parameters of the central source reveal a star at a highly evolved stage near to the white dwarf cooling track, being inconsistent with the born-again scenario. The nebula shows unexpectedly strong [N I] λ5200 and [O I] λ6300 emission lines indicating possible shock interactions. Abell 14 appears to be a member of a small group of highly evolved, extreme type-I planetary nebulae (PNe). The members of this group lie at the lower-left corner of the PNe regime on the [N II]/Hα versus [S II]/Hα diagnostic diagram, where shock-excited regions/objects are also placed. The low luminosity of their central stars, in conjunction with the large physical size of the nebulae, result in a very low photoionization rate, which can make any contribution of shock interaction easily perceptible, even for small velocities.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 2016
- DOI:
- 10.1093/mnras/stw038
- arXiv:
- arXiv:1601.02170
- Bibcode:
- 2016MNRAS.457.3409A
- Keywords:
-
- binaries: general;
- ISM: abundances;
- ISM: kinematics and dynamics;
- planetary nebulae: individual: Abell 14;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 12 pages, 9 figures and 4 tables, accepted for publication in MNRAS