ﻻ يوجد ملخص باللغة العربية
We aim at describing and understanding binary interaction processes in systems with very evolved companions. Here, we focus on understanding the origin and determining the properties of the high-velocity outflow observed in one such system. We present a quantitative analysis of BD+46$^{circ}$442, a post-AGB binary which shows active mass transfer that leads to the creation of a disk-driven outflow or jet. We obtained high-resolution optical spectra from the HERMES spectrograph, mounted on the 1.2m Flemish Mercator Telescope. By performing a time-series analysis of the Halpha profile, we dissected the different components of the system. We deduced the jet geometry by comparing the orbital phased data with our jet model. In order to image the accretion disk around the companion of BD+46$^{circ}$442, we applied the technique of Doppler tomography. The orbital phase-dependent variations in the Halpha profile can be related to an accretion disk around the companion, from which a high-velocity outflow or jet is launched. Our model shows that there is a clear correlation between the inclination angle and the jet opening angle. The latitudinally dependent velocity structure of our jet model shows a good correspondence to the data, with outflow velocities at least higher than 400km/s. We show that BD+46$^{circ}$442, is a result of a binary interaction channel. The origin of the fast outflow in this system can be attributed to a gaseous disk around the secondary component, which is most likely a main sequence star. Our analysis suggests the outflow to have a rather wide opening angle instead of being strongly collimated. Similar orbital phase-dependent Halpha profiles are commonly observed in post-AGB binaries. Post-AGB binaries provide ideal test bets to study jet formation and launching mechanisms over a wide range of orbital conditions.
I report the discovery that the 9th-magnitude Galactic-halo star BD+14$^circ$3061 is a member of the rare class of luminous metal-poor yellow post-AGB stars. Its Gaia DR2 parallax implies an absolute magnitude of $M_V=-3.44pm0.27$, and it is a very h
Binary post-asymptotic giant branch (post-AGB) stars have orbital periods in the range of 100--2500 days in eccentric orbits. They are surrounded by circumbinary dusty discs. They are the immediate result of unconstrained binary interaction processes
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
When the matter from a companion star is accreted towards the central compact accretor, i.e. a black hole (BH) or a neutron star (NS), an accretion disc and a jet outflow will form, providing bight X-ray and radio emission, which is known as X-ray bi
Many disc-type post-asymptotic giant branch (post-AGB) stars are chemically peculiar, showing underabundances of refractory elements in their photospheres that correlate with condensation temperature. The aim of this paper is to investigate how accre