Search Publications
Gaia search for stellar companions of TESS Objects of Interest III
Mugrauer, Markus; Michel, Kai-Uwe; Zander, Jule
The latest results from our ongoing multiplicity study of (Community) TESS Objects of Interest are presented, using astro- and photometric data from the ESA-Gaia mission, to detect stellar companions of these stars and characterize their properties. A total of 124 binary and 7 hierarchical triple star systems were detected among 2175 targets, whos…
Large-scale asymmetry in galaxy spin directions: Analysis of galaxies with spectra in DES, SDSS, and DESI Legacy Survey
Shamir, Lior
Multiple previous studies using several different probes have shown considerable evidence for the existence of cosmological-scale anisotropy and a Hubble-scale axis. One of the probes that show such evidence is the distribution of the directions toward which galaxies spin. The advantage of the analysis of the distribution of galaxy spin directions…
Effects of flares on the habitable zones of M dwarfs accessible to TESS planet detections
Stelzer, B.; Raetz, Stefanie; Bogner, M.
Photometric space missions like Kepler and TESS continuously discover new exoplanets and advance the search for a second habitable world. The light curves recorded by these telescopes also reveal signs of magnetic activity, such as star spot modulation and flares, which can influence habitability. Searching for these characteristics, we analyzed T…
First eROSITA-TESS results for M dwarfs: Mass dependence of the X-ray activity rotation relation and an assessment of sensitivity limits
Stelzer, B.; Raetz, St.; Magaudda, E.
We present a study of the activity-rotation relation for M dwarf stars, using new X-ray data from the ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Russian Spektrum-Roentgen-Gamma mission (SRG), combined with photometric rotation periods from the Transiting Exoplanet Survey Satellite (TESS). The stars used in this work are…
Optical spectroscopy of the Be/black hole binary MWC 656 - interaction of a black hole with a circumstellar disc
Bode, Michael F.; Stefanov, Stefan Y.; Marchev, Dragomir +7 more
We present new spectroscopic observations of the Be/black hole binary MWC 656 obtained during the period 2015-2021. We measure the equivalent width of Hα (EWα), Hβ (EWβ), and the distance between the peaks of Hα (ΔVα), Hβ (ΔVβ), and FeII (ΔVFeII) lines. Combining new and old data, we find that…
X-exoplanets coronal models and planet photoevaporation
Sanz-Forcada, Jorge
Follow‑up observations of the binary system γ Cep
Mugrauer, Markus; Buder, Sven; Ginski, Christian +2 more
We present new imaging and spectroscopic observations of the exoplanet host star $\gamma$ Cep A, and of its low-mass stellar companion $\gamma$ Cep B. We used AstraLux/CAHA to follow the orbital motion of the companion around its primary, whose radial velocity was determined with spectra of the star, taken with the spectrograph FLECHAS at the Univ…
Characterizing X-ray activity cycles of young solar-like stars with solar observations
Stelzer, Beate; Orlando, Salvatore; Coffaro, Martina
Throughout an activity cycle, magnetic structures rise to the stellar surface, evolve and decay. Tracing their evolution on a stellar corona allows us to characterize the X-ray cycles. However, directly mapping magnetic structures is feasible only for the Sun, while such structures are spatially unresolved with present-day X-ray instruments on ste…
Measurements of visual double stars with PISCO2 at the Nice 76-cm refractor in 2013-2014
Piccotti, Luca; Rivet, Jean-Pierre; Vakili, Farrokh +11 more
We present relative astrometric and photometric measurements of visual double stars made in 2013-2014 with PISCO2 installed at the 76-cm refractor of the Côte d'Azur Observatory in Nice (France). Our observation list contains orbital couples as well as double stars whose motion is still uncertain. Three different techniques were used for obtaining…
Detailed investigation of two high-speed evolved Galactic stars
Mucciarelli, Alessio; Aoki, Wako; Suda, Takuma +10 more
The study of metal poor stars provides clarification and knowledge about the primordial Universe. Specially, halo stars provide explanations of the nature of the first generations of stars and the nucleosynthesis in the metal-poor regime. We present a detailed chemical analysis and determination of the kinematic and orbital properties of two stars…