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The geometric challenge of testing gravity with wide binaries
El-Badry, Kareem
Wide binaries provide promising laboratories for testing general relativity (GR) in the low-acceleration regime. Recent observational studies have found that the difference in the proper motions and/or radial velocities of the components of nearby wide binaries appear larger than predicted by Kepler's laws, indicating a potential breakdown of GR a…
Multiplicity of Galactic Cepheids from long-baseline interferometry. IV. New detected companions from MIRC and PIONIER observations
Kervella, P.; Anderson, R. I.; Baron, F. +10 more
Aims: We aim at detecting and characterizing the main-sequence companions of a sample of known and suspected Galactic binary Cepheids. The long-term objective is to accurately and independently measure the Cepheid masses and distances.
Methods: We used the multi-telescope interferometric combiners CHARA/MIRC and VLTI/PIONIER to detect an…
Combining multiple structural inversions to constrain the solar modelling problem
Buldgen, G.; Eggenberger, P.; Meynet, G. +12 more
Context. The Sun is the most studied of all stars, which serves as a reference for all other observed stars in the Universe. Furthermore, it also serves the role of a privileged laboratory of fundamental physics and can help us better understand processes occuring in conditions irreproducible on Earth. However, our understanding of our star is cur…
Evolution of the Stellar Mass-Metallicity Relation. II. Constraints on Galactic Outflows from the Mg Abundances of Quiescent Galaxies
Treu, Tommaso; Ellis, Richard S.; Moran, Sean M. +2 more
We present the stellar mass-[Fe/H] and mass-[Mg/H] relation of quiescent galaxies in two galaxy clusters at z ∼ 0.39 and z ∼ 0.54. We derive the age, [Fe/H], and [Mg/Fe] for each individual galaxy using a full-spectrum fitting technique. By comparing with the relations for z ∼ 0 Sloan Digital Sky Survey galaxies, we confirm our previous finding th…
Additional fluorine abundance determinations in evolved stars
de Laverny, P.; Cunha, K.; Abia, C. +2 more
We present new fluorine abundance measurements for a sample of carbon-rich asymptotic giant branch (AGB) stars and two other metal-poor evolved stars of Ba/CH types. The abundances are derived from IR, K-band, high-resolution spectra obtained using GEMINI-S/Phoenix and TNG/Giano-b. Our sample includes an extragalactic AGB carbon star belonging to …
Phase-space Correlation in Stellar Streams of the Milky Way Halo: The Clash of Kshir and GD-1
Malhan, Khyati; Ibata, Rodrigo A.; Martin, Nicolas F. +3 more
We report the discovery of a 70^\circ long stellar stream in the Milky Way halo, which criss-crosses the well known “GD-1” stream. We show that this new stellar structure (“Kshir”) and GD-1 lie at similar distance, and are remarkably correlated in kinematics. We propose several explanations for the nature of this new structure and its possible ass…
Helium enrichment in intermediate-age Magellanic Clouds clusters: towards an ubiquity of multiple stellar populations?
Martocchia, S.; Salaris, M.; Bastian, N. +1 more
Intermediate-age star clusters in the Magellanic Clouds harbour signatures of the multiple stellar populations long thought to be restricted to old globular clusters. We compare synthetic horizontal branch models with Hubble Space Telescope photometry of clusters in the Magellanic Clouds, with age between ∼2 and ∼10 Gyr, namely NGC 121, Lindsay 1,…
The B-Star Exoplanet Abundance Study: a co-moving 16-25 MJup companion to the young binary system HIP 79098
Reffert, Sabine; Langlois, Maud; Delorme, Philippe +13 more
Wide low-mass substellar companions are known to be very rare among low-mass stars, but appear to become increasingly common with increasing stellar mass. However, B-type stars, which are the most massive stars within 150 pc of the Sun, have not yet been examined to the same extent as AFGKM-type stars in that regard. In order to address this issue…
High-precision Dynamical Masses of Pre-main-sequence Stars with ALMA and Gaia
Sheehan, Patrick D.; Tobin, John J.; Wu, Ya-Lin +1 more
The Keplerian rotation in protoplanetary disks can be used to robustly measure stellar masses at very high precision if the source distance is known. We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of spatially and spectrally resolved 12CO (2-1) emission toward the disks around 2MASS J16262774-2527247 (the te…
Dust emission profiles of DustPedia galaxies
Bianchi, S.; Fritz, J.; Madden, S. C. +19 more
Most radiative transfer models assume that dust in spiral galaxies is distributed exponentially. In this paper our goal is to verify this assumption by analysing the two-dimensional large-scale distribution of dust in galaxies from the DustPedia sample. For this purpose, we have made use of Herschel imaging in five bands, from 100 to 500 µm,…