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…
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…
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…
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…
X-ray irradiation of three planets around Hyades star K2 -136
Fernández Fernández, Jorge; Wheatley, Peter J.
We study the X-ray irradiation and likely photoevaporation of the three planets around the star K2-136. These are the Earth-sized K2-136 b, the mini-Neptune K2-136 c, and the super-Earth K2-136 d. XMM-Newton observations of the star indicate an X-ray luminosity of $(1.18\pm0.1)\times10^{28}$ erg s$^{-1}$ in the range 0.15 to 2.4 keV, resulting in …
Bright spectroscopic binaries: II. A study of five systems with orbital periods of P≲500 days
Jack, Dennis; Schröder, Klaus-Peter; Hernández Huerta, Missael Alejandro +1 more
We present a detailed analysis of five bright spectroscopic binary systems (HD 18665, HD 27131, HD 171852, HD 215550, and HD 217427) that have orbital periods of P≲500 days. We determined the complete set of orbital parameters using the toolkit RadVel by analyzing the observed radial velocity curves. To study the properties of the five systems, we…
A list of guest‑star records in Korean history and their possible counterparts
An, Hongjun; Park, Jaegeun; Jeon, Junhyeok
We report on guest‑star events recorded in Korean history in the period between A.D. 154 and 1807. We search five books, namely Joseonwangjosillok, Seungjeongwonilgi, Jeungbomoonheonbigo, Goryeosa, and Samguksagi for "guest star" and find 37 events. Seventeen of the guest stars are almost certainly comets as identified previously and are not astro…