Search Publications
Wolf-Rayet stars in the Small Magellanic Cloud. II. Analysis of the binaries
Sander, A.; Hamann, W. -R.; Oskinova, L. M. +7 more
Context. Massive Wolf-Rayet (WR) stars are evolved massive stars (MI ≳ 20 M⊙) characterized by strong mass-loss. Hypothetically, they can form either as single stars or as mass donors in close binaries. About 40% of all known WR stars are confirmed binaries, raising the question as to the impact of binarity on the WR populati…
The Close AGN Reference Survey (CARS). What is causing Mrk 1018's return to the shadows after 30 years?
Combes, F.; Scharwächter, J.; Eckart, A. +11 more
We recently discovered that the active galactic nucleus (AGN) of Mrk 1018 has changed optical type again after 30 yr as a type 1 AGN. Here we combine Chandra, NuStar, Swift, Hubble Space Telescope and ground-based observations to explore the cause of this change. The 2-10 keV flux declines by a factor of ~8 between 2010 and 2016. We show with our …
Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in supergiant fast X-ray transient and classical supergiant X-ray binaries
Sander, A.; Hamann, W. -R.; Shenar, T. +9 more
Context. Classical supergiant X-ray binaries (SGXBs) and supergiant fast X-ray transients (SFXTs) are two types of high-mass X-ray binaries (HMXBs) that present similar donors but, at the same time, show very different behavior in the X-rays. The reason for this dichotomy of wind-fed HMXBs is still a matter of debate. Among the several explanation…
The panchromatic spectroscopic evolution of the classical CO nova V339 Delphini (Nova Del 2013) until X-ray turnoff
Buil, C.; Scaringi, S.; Shore, S. N. +10 more
Context. Classical novae are the product of thermonuclear runaway-initiated explosions occurring on accreting white dwarfs.
Aims: V339 Del (Nova Delphinus 2013) was one of the brightest classical novae of the last hundred years. Spectroscopy and photometry are available from γ-rays through infrared at stages that have frequently not been obse…
Observational signatures of past mass-exchange episodes in massive binaries: The case of HD 149 404
Martins, F.; Gosset, E.; Nazé, Y. +4 more
Context. Mass and momentum exchanges in close massive binaries play an important role in their evolution, and produce several observational signatures such as asynchronous rotation and altered chemical compositions, that remain after the stars detach again.
Aims: We investigated these effects for the detached massive O-star binary HD 149 404 …
Mid-IR spectra of pre-main sequence Herbig stars: An explanation for the non-detections of water lines
Woitke, P.; Kamp, I.; Güdel, M. +7 more
Context. The mid-IR detection rate of water lines in disks around Herbig stars disks is about 5%, while it is around 50% for disks around T Tauri stars. The reason for this is still unclear.
Aims: In this study, we want to find an explanation for the different detection rates between low mass and high mass pre-main-sequence stars in the mid-I…
The far-infrared behaviour of Herbig Ae/Be discs: Herschel PACS photometry
Marshall, J. P.; Montesinos, B.; Mendigutía, I. +3 more
Herbig Ae/Be objects are pre-main sequence stars surrounded by gas- and dust-rich circumstellar discs. These objects are in the throes of star and planet formation, and their characterisation informs us of the processes and outcomes of planet formation processes around intermediate mass stars. Here we analyse the spectral energy distributions of d…
Stellar laboratories. VII. New Kr iv - vii oscillator strengths and an improved spectral analysis of the hot, hydrogen-deficient DO-type white dwarf RE 0503-289
Hoyer, D.; Rauch, T.; Werner, K. +4 more
Context. For the spectral analysis of high-resolution and high signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation.
Aims: New Kr iv-vii oscillator strengths …
Magnetic Doppler imaging of the chemically peculiar star HD 125248
Ilyin, I.; Ryabchikova, T.; Kochukhov, O. +1 more
Context. Intermediate-mass, chemically peculiar stars with strong magnetic fields provide an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in the atmospheres of these stars.
Aims: We reconstruct detailed maps of the surface magnetic fiel…
Wind mass transfer in S-type symbiotic binaries. II. Indication of wind focusing
Skopal, A.; Shagatova, N.; Cariková, Z.
Context. The wind mass transfer from a giant to its white dwarf companion in symbiotic binaries is not well understood. For example, the efficiency of wind mass transfer of the canonical Bondi-Hoyle accretion mechanism is too low to power the typical luminosities of the accretors. However, recent observations and modelling indicate a considerably …