Search Publications
Power spectra of solar brightness variations at various inclinations
Solanki, S. K.; Shapiro, A. I.; Tagirov, R. V. +4 more
Context. Magnetic features on the surfaces of cool stars lead to variations in their brightness. Such variations on the surface of the Sun have been studied extensively. Recent planet-hunting space telescopes have made it possible to measure brightness variations in hundred thousands of other stars. The new data may undermine the validity of setti…
Mono-enriched stars and Galactic chemical evolution. Possible biases in observations and theory
Strassmeier, K. G.; Ilyin, I.; Hansen, C. J. +9 more
A long sought after goal using chemical abundance patterns derived from metal-poor stars is to understand the chemical evolution of the Galaxy and to pin down the nature of the first stars (Pop III). Metal-poor, old, unevolved stars are excellent tracers as they preserve the abundance pattern of the gas from which they were born, and hence they ar…
Kalkayotl: A cluster distance inference code
Miret-Roig, N.; Bouy, H.; Casamiquela, L. +5 more
Context. The high-precision parallax data of the Gaia mission allows for significant improvements in the distance determination to stellar clusters and their stars. In order to obtain accurate and precise distance determinations, systematics such as parallax spatial correlations need to be accounted for, especially with regard to stars in small sk…
A census of the nearby Pisces-Eridanus stellar stream. Commonalities with and disparities from the Pleiades
Röser, Siegfried; Schilbach, Elena
Aims: Within a sphere of 400 pc radius around the Sun, we aim to search for members of the Pisces-Eridanus (Psc-Eri) stellar stream in the Gaia Data Release 2 data set. We compare basic astrophysical characteristics of the stream with those of the Pleiades.
Methods: We used a modified convergent-point method to identify stars with 2D vel…
Temperature and chemical species distributions in the middle atmosphere observed during Titan's late northern spring to early summer
Seignovert, B.; Teanby, N. A.; Flasar, F. M. +12 more
We present a study of the seasonal evolution of Titan's thermal field and distributions of haze, C2H2, C2H4, C2H6, CH3C2H, C3H8, C4H2, C6H6, HCN, and HC3N from March 2015 (Ls
The spin-orbit alignment of visual binaries
Albrecht, S.; Justesen, A. B.
Context. The angle between the stellar spin-axis and the orbital plane of a stellar or planetary companion has important implications for the formation and evolution of such systems. A study by Hale (1994, AJ, 107, 306) found that binaries with separations a ≲ 30 au are preferentially aligned while binaries on wider orbits are frequently misaligne…
FEDReD. II. 3D extinction map with 2MASS and Gaia DR2 data
Arenou, F.; Babusiaux, C.; Hottier, C.
Aims: We aim to map the 3D distribution of the interstellar extinction of the Milky Way disc up to distances larger than those probed with the Gaia parallax alone.
Methods: We applied the FEDReD (Field Extinction-Distance Relation Deconvolver) algorithm to the 2MASS near-infrared photometry together with the Gaia DR2 astrometry and photo…
The AMBRE Project: Spectrum normalisation influence on Mg abundances in the metal-rich Galactic disc
Recio-Blanco, A.; de Laverny, P.; Ordenovic, C. +2 more
Context. The abundance of α-elements provides an important fossil signature in Galactic archaeology to trace the chemical evolution of the different disc populations. High-precision chemical abundances are crucial to improving our understanding of the chemodynamical properties present in the Galaxy. However, deriving precise abundance estimations …
Optical and X-ray discovery of the changing-look AGN IRAS 23226-3843 showing extremely broad and double-peaked Balmer profiles
Schartel, N.; Komossa, S.; Kollatschny, W. +6 more
Aims: We detected a very strong X-ray decline in the galaxy IRAS 23226-3843 within the XMM-Newton slew survey in 2017. Subsequently, we carried out multi-band follow-up studies to investigate this fading galaxy in more detail.
Methods: We took deep follow-up Swift, XMM-Newton, and NuSTAR observations in combination with optical SALT spec…
Hypervelocity stars in the Gaia era. Revisiting the most extreme stars from the MMT HVS survey
Heber, U.; Irrgang, A.; Kreuzer, S.
The hypervelocity star (HVS) survey conducted at the Multiple Mirror Telescope (MMT) identified 42 B-type stars in the Galactic halo whose radial velocity in the Galactic rest-frame exceeds +275 km s-1. In order to unravel the nature and origin of those high-velocity outliers, their complete six-dimensional phase space information is ne…