Search Publications
A new sample of super-slowly rotating Ap (ssrAp) stars from the Zwicky Transient Facility survey
Paunzen, E.; Bernhard, K.; Hümmerich, S.
Context. The magnetic chemically peculiar Ap stars exhibit an extreme spread of rotational velocities, the cause of which is not clearly understood. Ap stars with rotation periods of 50 days or longer are know as super-slowly rotating Ap (ssrAp) stars. Photometrically variable Ap stars are commonly termed α2 Canum Venaticorum (ACV) vari…
Direct imaging and dynamical mass of a benchmark T-type brown dwarf companion to HD 167665
Lutz, D.; Genzel, R.; Sturm, E. +111 more
Context. A low-mass companion potentially in the brown dwarf mass regime was discovered on a ~12 yr orbit (~5.5 au) around HD 167665 using radial velocity (RV) monitoring. Joint RV–astrometry analyses confirmed that HD 167665B is a brown dwarf with precisions on the measured mass of ~4–9%. Brown dwarf companions with measured mass and luminosity a…
S-process nucleosynthesis in chemically peculiar binaries
Hansen, C. J.; Kubátová, B.; Stateva, I. +4 more
Context. Around half of the heavy elements in the Universe are formed through the slow neutron capture (s-) process, which takes place in thermally pulsing asymptotic giant branch (AGB) stars with masses of 1 ‑ 6 M⊙. The nucleosynthetic imprint of the s-process can be studied by observing the material on the surface of binary barium (Ba…
Dissecting the planetary nebula NGC 4361 with MUSE
Walsh, J. R.; Monreal Ibero, A.; Laging, J. +1 more
Context. Optical integral field spectroscopy of planetary nebulae (PNe) offers a unique tool to explore the spatial relationships between the complex mixture of the many components (neutral, low- and high-ionisation gas, dust, and the central star) and their underlying physical conditions. Aims. The optical line and continuum emission in the very-…
Measuring the diffuse interstellar bands at 5780, 5797, and 6614 Å in low-resolution spectra of cool stars from LAMOST
Jiang, Bi-Wei; Luo, A. -Li; Zhao, He +7 more
Context. The limited number of high-resolution spectra of hot stars is inadequate for statistical studies of diffuse interstellar bands (DIBs). In contrast, the vast quantity of low-resolution spectroscopic surveys on cool stars holds great potential for investigating the relationship between DIBs and the known interstellar medium (ISM), as well a…
Resolved properties of a luminous hinge clump in the compact group of galaxies NGC 6845
Torres-Flores, Sergio; Firpo, Veronica; Mora, Marcelo D. +2 more
Context. Compact groups of galaxies are unique places where galaxy-galaxy interactions play a mayor role on the evolution of its members. These strong gravitational encounters can induce star formation bursts.
Aims: We study the properties of one of the most luminous so-called hinge clumps that is located in the compact group of galaxies NGC …
Abnormal Stokes V profiles observed by Hinode in a sunspot: Detection of hidden photospheric fine-structures
Rezaei, R.; Hamedivafa, H.
Context. Hidden magnetic components in a sunspot are present as small-scale structures that are absent in low-resolution observations. Aims. We search for traces of the hidden magnetic components in spectro-polarimetric observations of a mature sunspot close to the disk center recorded by Hinode. Methods. To find extra humps in the far blue and re…
The return of FarNet-II: Generation of solar far-side magnetograms from helioseismic data
Asensio Ramos, A.; Felipe, T.; Broock, E. G.
Context. The far-side activity of the Sun can be inferred by interpreting the near-side wave field using local helioseismic techniques. However, detections are limited to strongly active regions because signal-to-noise ratio of the data is low. Recently, we developed the FarNet and FarNet-II neural networks to improve the identification of active …
Searching for orbital period modulation in X-ray observations of the symbiotic X-ray binary GX 1+4
Santangelo, Andrea; Ferrigno, Carlo; Bozzo, Enrico +3 more
The symbiotic X-ray binary GX 1+4 possesses a number of peculiar properties that have been studied since the early 1970s. In particular, the orbital period has been a point of debate for many years, until radial velocity measurements were able to settle the debate. These radial velocity findings have so far not been confirmed using X-ray data, eve…
Spectral evolution of hot hybrid white dwarfs: I. Spectral analysis
Rauch, Thomas; Werner, Klaus; Reindl, Nicole +1 more
Context. Hydrogen-rich white dwarfs (WDs) comprise the majority of the WD population, but are only rarely found at the very hot end of the WD cooling sequence. A small subgroup that exhibits both hydrogen and helium lines in their spectra, the so-called hybrid (or DAO) WDs, represents the majority of hydrogen-rich WDs at effective temperatures T