Search Publications
Multiple sites of recent wet-based glaciation identified from eskers in western Tempe Terra, Mars
Fawdon, Peter; Davis, Joel M.; Woodley, Savana Z. +4 more
Precipitation in Mars' mid-latitudes formed Viscous Flow Features (VFFs), landforms analogous to terrestrial debris-covered glaciers, in the last 1 Gyr. Until recently, the prevailing view was that the Amazonian environment was not conducive to basal melting of VFFs. However, recent identification of VFF-linked eskers (sedimentary ridges deposited…
The soft X-ray background with Suzaku. I. Milky Way halo
Sato, Kosuke; Yamasaki, Noriko Y.; Matsushita, Kyoko +4 more
We present measurements of the soft X-ray background emission for 130 Suzaku observations at 75° < l < 285° and |b| > 15° obtained from 2005 to 2015, covering nearly one solar cycle. In addition to the standard soft X-ray background model consisting of the local hot bubble and the Milky Way Halo (MWH), we include a hot collisional-ionizat…
X-ray selected narrow-line active galactic nuclei in the COSMOS field: Nature of optically dull active galactic nuclei
Murayama, Takashi; Fitriana, Itsna K.
X-ray emission detection in a galaxy is one of the efficient tools for selecting active galactic nuclei (AGNs). However, many X-ray-selected AGNs are not easily selected as AGNs by their optical emission. These galaxies, so-called optically dull (OD) AGNs, are fascinating since their X-ray emission is bright even though the AGN signature in the op…
Catalog of spiral arm tangents (Galactic longitudes) in the Milky Way, and the age gradient based on various arm tracers
Vallée, Jacques P.
An updated catalog of 205 observed tangents to the spiral arms (in Galactic longitudes) since 1980 is presented. This represents an addition of 80 arm tangents in 6 years (since 2016). Most arm tangents are observed at telescopes in the radio régime.
In this study, the separation of each arm tracer from the dust lane is analysed to obtain the…Radio observations of massive stars in the Galactic centre: The Quintuplet cluster
Alberdi, A.; Najarro, F.; Yusef-Zadeh, F. +4 more
We present high-angular-resolution radio continuum observations of the Quintuplet cluster, one of the most emblematic massive clusters in the Galactic centre. Data were acquired in two epochs and at 6 and 10 GHz with the Karl G. Jansky Very Large Array. With this work we have quadrupled the number of known radio stars in the cluster. Even though t…
Fundamental stellar parameters of benchmark stars from CHARA interferometry. III. Giant and subgiant stars
White, T. R.; Casagrande, L.; Nordlander, T. +3 more
Context. Large spectroscopic surveys of the Milky Way must be calibrated against a sample of benchmark stars to ensure the reliable determination of atmospheric parameters.
Aims: Here, we present new fundamental stellar parameters of seven giant and subgiant stars that will serve as benchmark stars for large surveys. The aim is to reach a pre…
Radio detection of chemically peculiar stars with LOFAR
White, Glenn J.; Haverkorn, Marijke; Vedantham, Harish +5 more
Context. Chemically peculiar stars are upper main sequence stars that show anomalies in their optical spectra. These anomalies suggest peculiar chemical abundances of certain elements. Some chemically peculiar stars possess strong magnetic fields. Electrons originating from the ionising stellar wind travel in the magnetosphere of the star and beco…
Statistics of BY Draconis chromospheric variable stars
de Grijs, Richard; Kamath, Devika; Chen, Xiaodian +1 more
We present an extensive catalogue of BY Draconis (BY Dra)-type variables and their stellar parameters. BY Dra are main-sequence FGKM-type stars. They exhibit inhomogeneous starspots and bright faculae in their photospheres. These features are caused by stellar magnetic fields, which are carried along with the stellar disc through rotation and whic…
High-contrast, high-angular resolution view of the GJ 367 exoplanet system
Brandner, Wolfgang; Calissendorff, Per; Cantalloube, Faustine +1 more
We search for additional companions in the GJ 367 exoplanet system and aim to better constrain its age and evolutionary status. We analyse high-contrast direct imaging observations obtained with HST/NICMOS, VLT/NACO, and VLT/SPHERE. We investigate and critically discuss conflicting age indicators based on theoretical isochrones and models for Gala…
Peculiar hydrogen-deficient carbon stars: strontium-rich stars and the s-process
Clayton, Geoffrey C.; Tisserand, Patrick; Crawford, Courtney L. +1 more
Context. R Coronae Borealis (RCB) variables and their non-variable counterparts, the dustless Hydrogen-deficient Carbon (dLHdC) stars have been known to exhibit enhanced s-processed material on their surfaces, especially Sr, Y, and Ba. No comprehensive work has been done to explore the s-process in these types of stars, however one particular RCB …