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Discovery of Two Nearby Post-T Tauri Stellar Associations
Fang, Min; Liu, Chao; Liu, Jiaming
In this work we report the discovery of two new stellar associations in close vicinity of the Sun at roughly 180 and 150 pc. These two associations, u Tau assoc and e Tau assoc, were detected based on their clustering in a multi-dimensional parameter space including α, δ, µα, µδ, and ϖ of Gaia. The fitting of pre-…
Deciphering the nature of the pulsar wind nebula CTB 87 with XMM-Newton
Safi-Harb, S.; Kothes, R.; Bucciantini, N. +5 more
CTB 87 (G74.9+1.2) is an evolved supernova remnant (SNR) which hosts a peculiar pulsar wind nebula (PWN). The X-ray peak is offset from that observed in radio and lies towards the edge of the radio nebula. The putative pulsar, CXOU J201609.2+371110, was first resolved with Chandra and is surrounded by a compact and a more extended X-ray nebula. He…
Asymptotic kinematics of globular clusters: The emergence of a Tully-Fisher relation
Hernandez, X.; Lara-D I, A. J.
Using a recent homogeneous sample of 40 high-quality velocity dispersion profiles for Galactic globular clusters, we study the regime of low gravitational acceleration relevant to the outskirts of these systems. We find that a simple empirical profile having a central Gaussian component and a constant large-radius asymptote, σ∞, accurat…
Interpreting Observations of Absorption Lines in the Circumgalactic Medium with a Turbulent Medium
Fumagalli, Michele; Buie, Edward, II; Scannapieco, Evan
Single-phase photoionization equilibrium (PIE) models are often used to infer the underlying physical properties of galaxy halos probed in absorption with ions at different ionization potentials. To incorporate the effects of turbulence, we use the Models of Agitated and Illuminated Hindering and Emitting Media (MAIHEM) code to model an isotropic …
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…