Search Publications
Gaia search for stellar companions of TESS Objects of Interest
Mugrauer, Markus; Michel, Kai-Uwe
The first results of a new survey, which explores the second data release of the ESA Gaia mission, are reported in order to search for stellar companions of (Community) TESS Objects of Interest and to characterize their properties. In total, 193 binary and 15 hierarchical triple star systems are presented, detected among 1,391 target stars, which …
Rotation of open clusters based on Gaia data. Praesepe
Popov, Alexander A.; Loktin, Alexander V.
High–precision trigonometric parallaxes, proper motions, and radial velocities of the Gaia DR2 catalog allow us to investigate the problem of open clusters rotation. Such a study could naturally be started with the clusters closest to the Sun, so we chose Praesepe as an object of our study. We selected 908 probable cluster members up to the appare…
The first stellar parallaxes revisited
Menten, Karl M.; Reid, Mark J.
We have reanalyzed the data used by Bessel, von Struve, and Henderson in the 1830s to measure the first parallax distances to stars. We can generally reproduce their results, although we find that von Struve and Henderson have underestimated some of their measurement errors, leading to optimistic parallax uncertainties. We find that temperature co…
The rotation-activity relation of M dwarfs: From K2 to TESS and PLATO
Stelzer, Beate; Scholz, Alexander; Raetz, Stefanie
Studies of the rotation-activity relation of late-type stars are essential to enhance our understanding of stellar dynamos and angular momentum evolution. We study the rotation-activity relation with K2 for M dwarfs, where it is especially poorly understood. We analyzed the light curves of all bright and nearby M dwarfs form the Superblink proper …
Flickering of the jet‑ejecting symbiotic star MWC 560
Stoyanov, K. A.; Latev, G.; Boeva, S. +4 more
We analyzed the optical photometric data of short‑term variability (flickering) of the accreting white dwarf in the jet‑ejecting symbiotic star MWC 560. The observations were obtained on 17 nights during the period November 2011 to October 2019. The color‑magnitude diagram shows that the hot component of the system becomes redder as it gets bright…
Spectroscopic characterization of nine binary star systems as well as HIP 107136 and HIP 107533
Neuhäuser, R.; Mugrauer, M.; Bischoff, R. +6 more
We present the results of our second radial velocity (RV) monitoring campaign, carried out with the Échelle spectrograph FLECHAS at the University Observatory Jena in the course of the Großschwabhausen binary survey between December 2016 and June 2018. The aim of this project is to obtain precise RV measurements for spectroscopic binary stars in o…
Bright spectroscopic binaries: I. Orbital parameters of five systems with periods of P < 365 days
Jack, Dennis; Schröder, Klaus-Peter; Hernández Huerta, Missael Alejandro
In a well‑aimed search based on the recently published Gaia DR2 radial velocity data and performed with the robotic TIGRE telescope, we have discovered 19 bright (mV < 7.66 mag) spectroscopic binary stars. We present the radial velocity curves of five of these stars (HD 20656, HD 27259, HD 98812, HD 150600, HD 193082) with periods of P < 365…
Identification of young nearby runaway stars based on Gaia data and the lithium test†
Torres, Guillermo; Mugrauer, Markus; Lux, Oliver +6 more
Young nearby runaway stars are suitable to search for their place of origin and possibly associated objects, for example, neutron stars. Tetzlaff et al. (2011) selected young (≤50 Myr) runaway star candidates from Hipparcos, for which they had estimated the ages from the location in the Hertzsprung-Russell diagram and evolutionary models. Here, we…
Observability of ultraviolet NI lines in the atmosphere of transiting Earth-like planets
France, Kevin; Cubillos, Patricio E.; Fossati, Luca +5 more
Nitrogen is a biosignature gas that cannot be maintained in its Earth-like ratio with CO2 under abiotic conditions. It has also been proven to be notoriously hard to detect at optical and infrared wavelengths. Fortunately, the ultraviolet region, which has only recently started being explored for terrestrial exoplanets, may provide new …
NLTE C and O abundances in RR lyrae stars
Wallerstein, George; Korotin, Sergey A.; Huang, Wenjin +5 more
The high excitation levels that form the O I and C I lines seen in RR Lyrae stars have long been known not to obey local thermodynamic equilibrium (LTE) statistics. We have observed 21 RR Lyrae and related stars with the Apache Point Observatory echelle spectrograph on the 3.5-m telescope and, for the first time, have derived abundances using non-…