Keplerian disks and outflows in binary post-AGB stars

TL;DR

This study investigates the morphology, kinematics, and molecular composition of binary post-AGB stars with Keplerian disks and outflows, revealing a new subclass of outflow-dominated nebulae and providing detailed molecular surveys.

Contribution

It introduces the first detailed models and molecular surveys of binary post-AGB stars, identifying a new subclass with dominant outflows and analyzing their molecular content and mass distribution.

Findings

AC Her is disk-dominated with 95% of nebular mass in the disk.

89 Her, IRAS 19125+0343, and R Scuti are outflow-dominated nebulae.

Sources generally show low molecular richness, especially in disk-dominated systems.

Abstract

There is a class of binary post-AGB stars that are surrounded by Keplerian disks and that often present outflows resulting from gas escaping from the disk. We present maps and complex models of 12CO and 13CO J=2-1 emission lines for four objects: AC Herculis, 89 Herculis, IRAS 19125+0343, and R Scuti. Our maps and models allow us to study their morphology, kinematics, and mass distribution. Our maps and modeling of AC Her reveal that 95% of the total nebular mass is located in the disk. So this source is a disk-dominated source (like the Red Rectangle, IW Carinae, IRAS 08544-4431). On the contrary, our maps and modeling of 89 Herculis, IRAS 19125+0343, and R Scuti suggest that the outflow is the dominant component of the nebula, resulting in a new subclass nebulae around binary post-AGB stars: the outflow-dominated ones. Besides CO, the molecular content of this kind of sources was barely known. We also present the first and very deep single-dish radio molecular survey in the 1.3, 2, 3, 7, and 13 mm bands. Our results allow us to classify our sources as O- or C-rich. We also conclude that these sources present in general a low molecular richness, especially those that are disk-dominated, compared to circumstellar envelopes around AGB stars and other post-AGB stars. This thesis presents a comprehensive study at millimetre wavelengths. On the one hand, we perform a detailed kinetic study of these objects through NOEMA interferometric observations and complex models. On the other hand, we study the chemistry of these sources, thanks to our sensitive single-dish observations. The union of these different methods yields a comprehensive study of the molecular gas present in these sources. Hopefully, this Ph.D. thesis will become a reference for future studies of molecular gas in nebulae around binary post-AGB stars.