TY - JOUR A1 - Mohamed, S. A1 - Mackey, J. A1 - Langer, N. A1 - Podsiadlowski, Philipp T1 - Shaping the outflows of Wolf-Rayet stars JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - Wolf-Rayet (WR) stars lose copious amounts of mass and momentum through dense stellar winds. The interaction of these outflows with their surroundings results in highly structured and complex circumstellar environments, often featuring knots, arcs, shells and spirals. Recent improvements in computational power and techniques have led to the development of detailed, multi-dimensional simulations that have given new insight into the origin of these structures, and better understanding of the physical mechanisms driving their formation. We review three of the main mechanisms that shape the outflows of WR stars: • interaction with the interstellar medium (ISM), i.e., wind-ISM interactions; • interaction with a stellar wind, either from a previous phase of evolution or the wind from a companion star, i.e., wind-wind interactions; • and interaction with a companion star that has a weak or insignificant outflow (e.g., a compact companion such as a neutron star or black hole), i.e.,wind-companion interactions. We also highlight the broader implications and impact of these circumstellar structures for related phenomena, e.g., for X-ray binaries and Gamma-ray bursts. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-88200 SP - 283 EP - 288 ER - TY - JOUR A1 - Neunteufel, Patrick A1 - Preece, H. A1 - Kruckow, Matthias U. A1 - Geier, Stephan A1 - Hamers, Adrian S. A1 - Justham, S. A1 - Podsiadlowski, Philipp T1 - Properties and applications of a predicted population of runaway He-sdO/B stars ejected from single degenerate He-donor SNe JF - Astronomy and astrophysics : an international weekly journal N2 - Context. Thermonuclear supernovae (SNe), a subset of which are the highly important SNe of Type Ia and Iax, are relatively poorly understood phenomena. One of the more promising scenarios leading up to the creation of a thermonuclear SN involves accretion of helium-rich material from a binary companion. Following the SN, the binary companion is then ejected from the location of the progenitor binary at velocities possibly large enough to unbind it from the gravitational potential of the Galaxy. Ejected companion stars should form a detectable population, if their production mechanism is not exceedingly rare. Aims. This study builds on previous works, producing the most extensive prediction of the properties of such a hypothetical population to date, taking both Chandrasekhar and non-Chandrasekhar mass events into account. These results are then used to define criteria for membership of this population and characterise putative subpopulations. Methods. This study contains 6 x 10(6) individual ejection trajectories out of the Galactic plane calculated with the stellar kinematics framework SHyRT, which are analysed with regard to their bulk observational properties. These are then put into context with the only previously identified population member US 708 and applied to a number of other possible candidate objects. Results. We find that two additional previously observed objects possess properties to warrant a designation as candidate objects. Characterisation of these object with respect to the predicted population finds all of them to be extreme in at least one astrometric observable. Higher mass ( >0 :7 M-circle dot) objects should be over-represented in the observationally accessible volume, with the ratio of bound to unbound objects being an accessible observable for the determination of the dominant terminal accretor mass. We find that current observations of runaway candidates within 10 kpc support a Galactic SN rate of the order of similar to 3 x 10(-7) yr(-1) to similar to 2 x 10(-6) yr(-1), three orders of magnitude below the inferred Galactic SN Ia rate and two orders of magnitude below the formation rate of predicted He-donor progenitors. Conclusions. The number of currently observed population members suggests that the He-donor scenario, as suspected before, is not a dominant contributor to the number of observed SNe Ia. However, even at the low event rate suggested, we find that the majority of possibly detectable population members is still undetected. The extreme nature of current population members suggests that a still larger number of objects has simply evaded detection up to this point, hinting at a higher contribution than is currently supported by observation. KW - binaries: close KW - stars: kinematics and dynamics KW - stars: distances KW - supernovae: general KW - subdwarfs KW - white dwarfs Y1 - 2022 U6 - https://doi.org/10.1051/0004-6361/202142864 SN - 0004-6361 SN - 1432-0746 VL - 663 PB - EDP Sciences CY - Les Ulis ER -