Search Publications
An accurate strong lensing model of the Abell 2163 core
Grillo, C.; Rosati, P.; Lombardi, M. +6 more
Abell 2163 at z ≃ 0.201 is one of the most massive galaxy clusters known, very likely in a post-merging phase. Data from several observational windows suggest a complex mass structure with interacting subsystems, which makes the reconstruction of a realistic merging scenario very difficult. A missing key element in this sense is unveiling the clus…
The structure of Titan's atmosphere from Cassini radio occultations: One- and two-way occultations
French, Richard G.; Achterberg, Richard K.; Flasar, F. Michael +5 more
We present the results of the remaining ten soundings of Titan's atmosphere by radio occultations using the Cassini spacecraft that have not been previously reported. Three were in 2008 and 2009, and used the Ultra Stable Oscillator onboard the spacecraft. The rest were in 2014 and 2016 after the USO had failed and were executed in two-way mode. C…
Benchmarking the fundamental parameters of Ap stars with optical long-baseline interferometric measurements
Shulyak, D.; Ryabchikova, T.; Meilland, A. +10 more
Context. The variety of physical processes at play in chemically peculiar stars makes it difficult to determine their fundamental parameters. In particular, for the magnetic ones, called Ap stars, the strong magnetic fields and the induced spotted stellar surfaces may lead to biased effective temperatures when these values are derived through spec…
Detailed abundances in a sample of very metal-poor stars
Bonifacio, P.; Caffau, E.; Spite, M. +6 more
Context. Unevolved metal-poor stars bore witness to the early evolution of the Galaxy, and the determination of their detailed chemical composition is an important tool to understand its chemical history. The study of their chemical composition can also be used to constrain the nucleosynthesis of the first generation of supernovae that enriched th…
Deuterium fractionation of nitrogen hydrides: detections of NHD and ND2
Pagani, L.; Kobayashi, K.; Hily-Blant, P. +5 more
Although ammonia is an abundant molecule commonly observed towards the dense interstellar medium, it has not yet been established whether its main formation route is from gas-phase ion-molecule reactions or grain-surface hydrogen additions on adsorbed nitrogen atoms. Deuterium fractionation can be used as a tool to constrain formation mechanisms. …
3D structure of the H II region Sh2-235 from tunable-filter optical observations
Wiebe, D. S.; Moiseev, A. V.; Kirsanova, M. S. +2 more
We present observations of the H α, H β, [S II] λλ6716, 6731 and [N II] λ6583 emission lines in the galactic H II region Sh2-235 with the Mapper of Narrow Galaxy Lines (MaNGaL), a tunable filter at the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. We show that the H II region is obscured by neutral mate…
Orbital Period Analysis of Four Eclipsing Binaries XY Boo, RW Com, MR Del and AK Her
Yılmaz, M.; Selam, S. O.; Özavcı, İ. +9 more
The orbital period variations of the eclipsing binaries XY Boo, RW Com, MR Del, and AK Her are investigated. This study includes the first orbital period analysis of the detached eclipsing binary MR Del and necessary updates for the remaining stars with addition of new mid-eclipse times calculated from our recent observations carried out at Ankara…
Extratidal Stars and Chemical Abundance Properties of Two Metal-poor Globular Clusters M53 (NGC 5024) and NGC 5053
Lee, Jae-Joon; Lim, Dongwook; Chun, Sang-Hyun
We search for extratidal stars around two metal-poor Galactic globular clusters, M53 and NGC 5053, using the near-infrared APOGEE spectra. Applying the t-distributed stochastic neighbor embedding (t-SNE) algorithm on the chemical abundances and radial velocities results in identification of two isolated stellar groups composed of cluster member st…
Dust in the Wolf-Rayet nebula M 1-67
Toalá, J. A.; Jiménez-Hernández, P.; Arthur, S. J.
The Wolf-Rayet nebula M 1-67 around WR 124 is located above the Galactic plane in a region mostly empty of interstellar medium, which makes it the perfect target to study the mass-loss episodes associated with the late stages of massive star evolution. Archive photometric observations from Wide-field Infrared Survey Explorer(WISE), Spitzer (MIPS),…
The rich lack close neighbours: the dependence of blue-straggler fraction on metallicity
Wyse, Rosemary F. G.; Kratter, Kaitlin M.; Moe, Maxwell
Blue-straggler stars (BSS) have been identified in star clusters and in field populations in our own Milky Way galaxy and in its satellite galaxies. They manifest as stars bluer and more luminous than the dominant old population, and usually have a spatial distribution that follows the old population. Their progenitors are likely to have been clos…