Most planetary nebulae (PNe) show beautiful, axisymmetric morphologies despite their progenitor stars being essentially spherical. Angular momentum provided by a close binary companion is widely invoked as the main agent that would help eject an axisymmetric nebula, after a brief phase of engulfment of the secondary within the envelope of the Asymptotic Giant Branch (AGB) star, known as a common envelope (CE). The evolution on the AGB would thus be interrupted abruptly, its (still quite) massive envelope fully ejected to form the PN, which should be more massive than a PN coming from the same star were it single. We test this hypothesis by deriving the ionised+molecular masses of a pilot sample of post-CE PNe and comparing them to a regular PNe sample. We find the mass of post-CE PNe to be actually lower, on average, than their regular counterparts, raising some doubts on our understanding of these intriguing objects.
- Pub Date:
- December 2019
- (ISM:) planetary nebulae: general;
- (stars:) binaries: close;
- ISM: jets and outflows;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- 4 pages, 1 figure, to appear on the proceedings of the IAU Symposium 343: "Why Galaxies Care About AGB Stars: A Continuing Challenge through Cosmic Time"