Related papers: Numerical models for the circumstellar medium arou…
We present a high-resolution spectral analysis of Betelgeuse (M2 Iab). Between 1998 January and 1999 March four spatially resolved raster scans (http://cfa-www.harvard.edu/cfa/ep/pressrel/alobel0100.html) have been obtained with the STIS on…
Massive stars that have been ejected from their parent cluster and supersonically sailing away through the interstellar medium (ISM) are classified as exiled. They generate circumstellar bow shock nebulae that can be observed. We present…
Massive stars are key contributors to the chemodynamical evolution of galaxies and the Universe. Despite their significance, discrepancies between observational data and theoretical models of massive stars challenge our understanding of…
Context. State of the art simulations of astrospheres are modelled using three-dimensional (3D) magnetohydrodynamics (MHD). An astrospheric interaction of a stellar wind (SW) with its surrounding interstellar medium (ISM) can only generate…
We present two dimensional cylindrically symmetric hydrodynamic simulations and synthetic emission maps of a stellar wind propagating into an infalling, rotating environment. The resulting outflow morphology, collimation and stability…
Blue supergiant stars are known to display photometric and spectroscopic variability that is suggested to be linked to stellar pulsations. Pulsational activity in massive stars strongly depends on the star's evolutionary stage and is…
It has been well established from a variety of observations that red supergiants (RSGs) loose a lot of mass in stellar wind. Dust formed in this emitted gas over a few decades before core-collapse can lead to substantial extinction and…
We discuss two important effects for the astrospheres of runaway stars: the propagation of ionizing photons far beyond the astropause, and the rapid evolution of massive stars (and their winds) near the end of their lives. Hot stars emit…
Since its formation 4.6 billion years ago, our solar system has most likely crossed numerous magnetized interstellar clouds and bubbles of different sizes and contents on its path through the Milky Way. Having a reference model for how the…
OGLE-2002-BLG-360 is an example of a Galactic red nova, the aftermath of a non-compact stellar merger. The dusty nature of the circumstellar environment makes observations of this particular source difficult, meaning the properties of the…
Massive stars less massive than ~30 Msol evolve into a red supergiant after the main sequence. Given a standard IMF, this means about 80% of all single massive stars will experience this phase. RSGs are dominated by convection, with a…
Hydrodynamic jets, underdense with respect to their environment by a factor of up to 10,000, were computed in axisymmetry as well as in 3D. They finally reached a size of up to 220 jet radii, corresponding to a 100 kpc sized radio galaxy.…
Beyond the main sequence solar type stars undergo extensive mass loss, providing an environment where planet and brown dwarf companions interact with the surrounding material. To examine the interaction of substellar mass objects embedded…
Direct images of Betelgeuse were obtained over a span of 4 years with the Faint Object Camera on the Hubble Space Telescope. These images reveal the extended ultraviolet continuum emission (about 2 times the optical diameter), the varying…
During the core collapse of massive stars that do not undergo a canonical energetic explosion, some of the hydrogen envelope of a red supergiant (RSG) progenitor may infall onto the newborn black hole (BH). Within the Athena++ framework, we…
Wolf-Rayet stars are advanced evolutionary stages of massive stars. Despite their large mass-loss rates and high wind velocities, none of them display a bow shock, although a fraction of them are classified as runaway. Our 2.5-D numerical…
Wolf-Rayet stars are amongst the rarest but also most intriguing massive stars. Their extreme stellar winds induce famous multi-wavelength circumstellar gas nebulae of various morphologies, spanning from circles and rings to bipolar shapes.…
Blue straggler stars (BSSs) are brighter and bluer than the main-sequence (MS) turnoff and more massive than MS stars.Two scenarios for their formation have been proposed: collision-induced stellar mergers (COL-BSSs),or mass-transfer in…
We previously proposed that Betelgeuse might have been spun up by accreting a companion of about 1 solar mass. Here we explore in more detail the possible systematics of such a merger and a larger range of accreted masses. We use the…
We use mid-IR images from the Spitzer Cygnus~X Legacy Survey to search for stellar bowshocks, a signature of early type "runaway" stars with high space velocities. We identify ten arc-shaped nebulae containing centrally located stars as…