Search Publications
A multiyear photopolarimetric study of the semi-regular variable V CVn and identification of analog sources
Ignace, R.; Simpson, J.; Shrestha, M. +4 more
The semi-regular variable star V Canum Venaticorum (V CVn) is well known for its unusual linear polarization position angle (PA). Decades of observing V CVn reveal a nearly constant PA spanning hundreds of pulsation cycles. This phenomenon has persisted through variability that has varied by two magnitudes in optical brightness and through variabi…
Long-period radial velocity variations of nine M red giants. The detection of substellar companions around HD 6860 and HD 112300
Lee, Byeong-Cheol; Do, Hee-Jin; Park, Myeong-Gu +7 more
Context. Certain periodic variations of radial velocities (RVs) of wobbling giants originate from exoplanets. A number of exoplanets have been discovered around giant stars.
Aims: The purpose of our study is to find low-amplitude and long-period RV variations around bright M (super) giants in the red giant branch (or asymptotic giant branch) …
3D stellar motion in the axisymmetric Galactic potential and the e-z resonances
Barros, Douglas A.; Michtchenko, Tatiana A.
Context. The full phase-space information on the kinematics of a huge number of stars provided by Gaia Data Release 3 increases the demand for a better understanding of the 3D stellar dynamics.
Aims: In this paper, we investigate the possible regimes of motion of stars in the axisymmetric approximation of the Galactic potential, applying a 3D…
New red giants in NGC 6791 and NGC 6819 using Kepler superstamps
Hekker, S.; Covelo-Paz, A.; Themeßl, N. +1 more
Context. Stars that are members of stellar clusters are assumed to be formed at the same time and place from material with the same initial chemical composition. These additional constraints on the ensemble of cluster stars make these stars suitable as benchmarks.
Aims: We aimed (1) to identify previously unknown red giants in the open cluste…
Discovery of an extended G giant chromosphere in the 2019 eclipse of γ Per
Schmitt, J. H. M. M.; Fridlund, M.; Schröder, K. -P. +3 more
The November 2019 eclipse of γ Per was a rare opportunity to seek evidence for a chromosphere of the G8 giant, hitherto suspected but not detected. Twenty-nine years after the only other observed eclipse, we aim to find chromospheric absorption in the strong Ca II H&K lines, and to determine its column densities and scale height. Using the Tel…
Iron Kα echoes from the circumnuclear disk orbiting Sgr A⋆
Haardt, Francesco; Ponti, Gabriele; Stel, Giovanni
Context. Molecular clouds in the Galactic center (GC) reprocess radiation from past outbursts of nearby high-energy sources, generating a bright Fe Kα fluorescence at 6.4 keV. The closest clouds to the GC are only ≃1.5 pc from Sgr A⋆, forming a torus-like structure known as the circumnuclear disk (CND). The study of fluorescence emissio…
Linear and nonlinear kinetic Alfvén waves at Venus
Fichtner, H.; Lazar, M.; Moslem, W. M. +1 more
Space observations show that Venus suffers significant atmospheric erosion caused by the solar wind forcing. Plasma acceleration is found to be one of the main mechanisms contributing to the global atmospheric loss at Venus through its magnetotail. Motivated by these observations, we propose that kinetic Alfvén waves (KAW) may be a possible candid…
[C I] and [C II] emission in the circumstellar envelope of IRC +10216. I. Observational data and NLTE modelling of the [C I] emission
Menten, K. M.; Wyrowski, F.; Wiesemeyer, H. +1 more
Context. The envelopes of evolved late-type stars on the asymptotic giant branch are characterised by a complex chemistry that is close to thermochemical equilibrium near the stellar surface; however, in the outer envelope, it is dominated by radical reactions, assisted by a photo-chemistry driven by the interstellar radiation field.
Aims: Th…
Magnetic holes between Earth and Mercury: BepiColombo cruise phase
Glassmeier, K. -H.; Karlsson, T.; Nakamura, R. +14 more
Context. Magnetic holes are ubiquitous structures in the solar wind and in planetary magnetosheaths. They consist of a strong depression of the magnetic field strength, most likely in pressure balance through increased plasma pressure, which is convected with the plasma flow. These structures are created through a plasma temperature anisotropy, wh…
Multiwavelength and astrometric study of the DBS 89−90−91 embedded clusters region
Orellana, R. B.; Suad, L. A.; Corti, M. A. +1 more
Aims: Our main aims are to improve our understanding of the main properties of the radio source G316.8−0.1 (IRAS 14416−5937) where the DBS 89−90−91 embedded clusters are located, to identify the stellar population present in this region, and to study the interaction of these stars with the interstellar medium.
Methods: We analyzed some c…