Search Publications
High-precision chemical abundances of Galactic building blocks. II. Revisiting the chemical distinctness of the Helmi streams
Hattori, Kohei; Helmi, Amina; Ishigaki, Miho N. +6 more
Context. The Helmi streams are a kinematic substructure whose progenitor is likely a dwarf galaxy. Although 20 years have passed since their discovery, it is still unclear whether their members are chemically distinguishable from other halo stars in the Milky Way.
Aims: We aim to precisely characterize the chemical properties of the Helmi str…
Inferring the HII region escape fraction of ionizing photons from infrared emission lines in metal-poor star-forming dwarf galaxies
Morisset, C.; Schaerer, D.; Ramambason, L. +8 more
Local metal-poor galaxies stand as ideal laboratories for probing the properties of the interstellar medium (ISM) in chemically unevolved conditions. Detailed studies of this primitive ISM can help gain insights into the physics of the first primordial galaxies that may be responsible for the reionization. Quantifying the ISM porosity to ionizing …
Performance of near-infrared high-contrast imaging methods with JWST from commissioning
Carter, Aarynn L.; Perrin, Marshall D.; Pueyo, Laurent +12 more
The James Webb Space Telescope (JWST) will revolutionize the field of high-contrast imaging and enable both the direct detection of Saturn-mass planets and the characterization of substellar companions in the mid-infrared. While JWST will feature unprecedented sensitivity, angular resolution will be the key factor when competing with ground-based …
Superresolution trends in the ALMA Taurus survey: structured inner discs and compact discs
Tazzari, Marco; Rosotti, Giovanni P.; Clarke, Cathie J. +2 more
The 1.33-mm survey of protoplanetary discs in the Taurus molecular cloud found annular gaps and rings to be common in extended sources (≳ 55AU), when their 1D visibility distributions were fit parametrically. We first demonstrate the advantages and limitations of non-parametric visibility fits for data at the survey's 0.12-arcsec resolution. Then …
First light for GRAVITY Wide. Large separation fringe tracking for the Very Large Telescope Interferometer
Lutz, D.; Förster Schreiber, N. M.; Genzel, R. +114 more
GRAVITY+ is the upgrade for GRAVITY and the Very Large Telescope Interferometer (VLTI) with wide-separation fringe tracking, new adaptive optics, and laser guide stars on all four 8 m Unit Telescopes (UTs) to enable ever-fainter, all-sky, high-contrast, milliarcsecond interferometry. Here we present the design and first results of the first phase …
A Maximum Likelihood Calibration of the Tip of the Red Giant Branch Luminosity from High Latitude Field Giants Using Gaia Early Data Release 3 Parallaxes
Casertano, Stefano; Li, Siyang; Riess, Adam G.
The calibration of the tip of the red giant branch (TRGB) in the I band has a direct role in determinations of the Hubble constant, a subject of recent interest due to the discrepancy between direct and indirect estimates of its value. We present a maximum likelihood method designed to obtain an independent calibration of the brightness of TRGB us…
Orbital and dynamical analysis of the system around HR 8799. New astrometric epochs from VLT/SPHERE and LBT/LUCI
Avenhaus, H.; Marzari, F.; Henning, Th. +45 more
Context. HR 8799 is a young planetary system composed of four planets and a double debris belt. Being the first multi-planetary system discovered with the direct imaging technique, it has been observed extensively since 1998. This wide baseline of astrometric measurements, counting over 50 observations in 20 years, permits a detailed orbital and d…
Luminosities and Masses of Single Galactic Post-asymptotic Giant Branch Stars with Distances from Gaia EDR3: The Revelation of an s-process Diversity
Ventura, Paolo; Van Winckel, Hans; Hrivnak, Bruce J. +4 more
Post-asymptotic giant branch (AGB) stars are exquisite probes of AGB nucleosynthesis. However, the previous lack of accurate distances jeopardized comparison with theoretical AGB models. The Gaia Early Data Release 3 (Gaia EDR3) has now allowed for a breakthrough in this research landscape. In this study, we focus on a sample of single Galactic po…
Complex Modulation of Rapidly Rotating Young M Dwarfs: Adding Pieces to the Puzzle
Jayaraman, Rahul; Kristiansen, Martti H.; Triaud, Amaury H. M. J. +37 more
New sets of young M dwarfs with complex, sharp-peaked, and strictly periodic photometric modulations have recently been discovered with Kepler/K2 (scallop shells) and TESS (complex rotators). All are part of star-forming associations, are distinct from other variable stars, and likely belong to a unified class. Suggested hypotheses include starspo…
Intrinsic Lyα Profiles of High-velocity G, K, and M Dwarfs
Redfield, Seth; France, Kevin; Youngblood, Allison +5 more
Observations of H I Lyman α, the brightest UV emission line of late-type stars, are critical for understanding stellar chromospheres and transition regions, modeling photochemistry in exoplanet atmospheres, and measuring the abundances of neutral hydrogen and deuterium in the interstellar medium. Yet Lyα observations are notoriously challenging ow…