ORCID Profile
0000-0002-7946-2114
Current Organisations
KU Leuven
,
Macquarie University
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Publisher: EDP Sciences
Date: 18-10-2019
DOI: 10.1051/0004-6361/201936073
Abstract: Aims. We aim to determine the geometry, density gradient, and velocity structure of jets in post-asymptotic giant branch (post-AGB) binaries. Methods. Our high cadence time series of high-resolution optical spectra of jet-creating post-AGB binary systems provide us with a unique tomography of the jet. We determine the spatio-kinematic structure of the jets based on these data by fitting the synthetic spectral line profiles created by our model to the observed, orbital phase-resolved, H α -line profiles of these systems. The fitting routine is provided with an initial spectrum and is allowed to test three configurations, derived from three specific jet launching models: a stellar jet launched by the star, an X-wind, and a disk wind configuration. We apply a Markov-chain Monte Carlo routine in order to fit our model to the observations. Our fitting code is tested on the post-AGB binary IRAS 19135+3937. Results. We find that a model using the stellar jet configuration gives a marginally better fit to our observations. The jet has a wide half-opening angle of about 76° and reaches velocities up to 870 km s −1 . Conclusions. Our methodology is successful in determining some parameters for jets in post-AGB binaries. The model for IRAS 19135+3937 includes a transparent, low density inner region (for a half-opening angle 40°). The source feeding the accretion disk around the companion is most likely the circumbinary disk. We will apply this jet fitting routine to other jet-creating post-AGB stars in order to provide a more complete description of these objects.
Publisher: Oxford University Press (OUP)
Date: 11-01-2021
Abstract: Jets are a commonly observed phenomenon in post-asymptotic giant branch (post-AGB) binaries. Due to the orbital motion of the binary, the jet causes variable absorption in the Balmer profiles. In previous work, we have developed spatio-kinematic and radiative transfer models to reproduce the observed Balmer line variability and derive the spatio-kinematic structure of the jet and its mass-loss rate. Here, we apply our jet model to five post-AGB binaries with distinct H α line variability and erse orbital properties. Our models fit the H α line variations very well. We estimate jet mass-loss rates between $10^{-8}\\,$M$_\\odot \\, \\text{yr}^{-1}$ and $10^{-4}\\,$ M$_\\odot \\, \\text{yr}^{-1}$, from which we deduce accretion rates on to the companion between $10^{-7}\\,$ M$_\\odot \\, \\text{yr}^{-1}$ and $10^{-3}\\,$ M$_\\odot \\, \\text{yr}^{-1}$. These accretion rates are somewhat higher than can be comfortably explained with reasonable sources of accretion, but we argue that the circumbinary disc in these systems is most likely the source feeding the accretion, although accretion from the post-AGB star cannot be ruled out. The ersity of the variability in the five objects is due to their wide ejection cones combined with a range of viewing angles, rather than inherent differences between the objects. The nature of the observations does not let us easily distinguish which jet launching model (stellar jet, disc wind, or X-wind) should be favoured. In conclusion, we show that our jet model includes the physical parameters to successfully reproduce the H α line variations and retrieve the structure and mass-loss rates of the jet for all five objects that are representative of the erse s le of Galactic post-AGB binaries.
Publisher: Cambridge University Press (CUP)
Date: 08-2019
DOI: 10.1017/S1743921318006555
Abstract: We have discovered jets in post-AGB binaries. The orbital motion allows us to carry out tomography of the jet as light from the primary star shines through the jet cone. Jets play a major role in many astrophysical environments, from young stellar objects to galaxies. They are also used to study the energetics of accretion phenomena in systems such as red transients and stellar mergers. We use high-resolution, optical, time-series spectra to constrain theories of jet launching, and the impact of jets on the evolution of these post-AGB binaries.
Publisher: EDP Sciences
Date: 11-2017
No related grants have been discovered for Dylan Bollen.