Search Publications
X-rays observations of a super-Chandrasekhar object reveal an ONe and a CO white dwarf merger product embedded in a putative SN Iax remnant
Todt, Helge; Langer, Norbert; Oskinova, Lidia M. +2 more
The merger of two white dwarfs (WDs) is a natural outcome of the evolution of many binary stars. Recently, a WD merger product, IRAS 00500+6713, was identified. IRAS 00500+6713 consists of a central star embedded in a circular nebula. The analysis of the optical spectrum of the central star revealed that it is hot, hydrogen, and helium free, and i…
Purveyors of fine halos. II. Chemodynamical association of halo stars with Milky Way globular clusters
Grebel, Eva K.; Hanke, Michael; Bastian, Ulrich +2 more
A long-lasting open question in the field of Galactic archeology refers to the size of the contribution from former globular cluster (GC) stars to the formation of the stellar halo of the Milky Way. We contribute to answering this important question by establishing observational links between the present-day halo field star population and GCs. To …
The solar wind from a stellar perspective. How do low-resolution data impact the determination of wind properties?
Güdel, M.; Airapetian, V. S.; Jin, M. +5 more
Context. Due to the effects that they can have on the atmospheres of exoplanets, stellar winds have recently received significant attention in the literature. Alfvén-wave-driven 3D magnetohydrodynamic models, which are increasingly used to predict stellar wind properties, contain unconstrained parameters and rely on low-resolution stellar magnetog…
Time-resolved photometry of the young dipper RX J1604.3-2130A. Unveiling the structure and mass transport through the innermost disk
Bouvier, J.; Manara, C. F.; Pinilla, P. +3 more
Context. RX J1604.3-2130A is a young, dipper-type, variable star in the Upper Scorpius association, suspected to have an inclined inner disk, with respect to its face-on outer disk.
Aims: We aim to study the eclipses to constrain the inner disk properties.
Methods: We used time-resolved photometry from the Rapid Eye Mount telescope and K…
Bar resonances and low angular momentum moving groups in the Galaxy revealed by their stellar ages
Laporte, Chervin F. P.; Famaey, Benoit; Gerhard, Ortwin +3 more
We use the second Gaia data release to dissect the Milky Way disc in phase-space and relative ages. We confirm and report the existence of multiple velocity moving groups at low azimuthal velocities and angular momenta, below Arcturus, regularly separated by ∼18-20 km s-1 in azimuthal velocity. Such features were predicted to exist more…
The challenge of measuring the phase function of debris discs. Application to HR 4796 A
Bayo, A.; Henning, Th.; Milli, J. +2 more
Context. Debris discs are valuable systems to study dust properties. Because they are optically thin at all wavelengths, we have direct access to the absorption and scattering properties of the dust grains. One very promising technique to study them is to measure their phase function, that is, the scattering efficiency as a function of the scatter…
Using radio triangulation to understand the origin of two subsequent type II radio bursts
Jebaraj, I. C.; Magdalenić, J.; Kilpua, E. K. J. +7 more
Context. Eruptive events such as coronal mass ejections (CMEs) and flares accelerate particles and generate shock waves which can arrive at Earth and can disturb the magnetosphere. Understanding the association between CMEs and CME-driven shocks is therefore highly important for space weather studies.
Aims: We present a study of the CME/flare…
Properties of carbon stars in the solar neighbourhood based on Gaia DR2 astrometry
de Laverny, P.; Kordopatis, G.; Abia, C. +2 more
Context. Stars evolving along the asymptotic giant branch (AGB) can become carbon rich in the final part of their evolution. The detailed description of their spectra has led to the definition of several spectral types: N, SC, J, and R. To date, differences among them have been partially established only on the basis of their chemical properties. …
Exploring velocity limits in the thermonuclear supernova ejection scenario for hypervelocity stars and the origin of US 708
Neunteufel, P.
Context. Hypervelocity stars (HVS) are a class of stars moving at velocities that are high enough to make them gravitationally unbound from the Galaxy. In recent years, ejection from a close binary system in which one of the components undergoes a thermonuclear supernova (SN) has emerged as a promising candidate production mechanism for the least …
The enigmatic globular cluster UKS 1 obscured by the bulge: H-band discovery of nitrogen-enhanced stars
Smith, Leigh C.; Beers, Timothy C.; Placco, Vinicius M. +13 more
The presence of nitrogen-enriched stars in globular clusters provides key evidence for multiple stellar populations (MPs), as has been demonstrated with globular cluster spectroscopic data towards the bulge, disk, and halo. In this work, we employ the VVV Infrared Astrometric Catalogue (VIRAC) and the DR16 SDSS-IV release of the APOGEE survey to p…