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The Geochemical Potential for Metabolic Processes on the Sub-Neptune Exoplanet K2-18b
Glein, Christopher R.
Quantifying disequilibria is important to understand whether an environment could be habitable. It has been proposed that the exoplanet K2-18b has a hydrogen-rich atmosphere and a water ocean, making it a "hycean world." The James Webb Space Telescope recently made measurements of methane, CO2, and possibly dimethyl sulfide (DMS) in the…
Atmospheric Retrievals Suggest the Presence of a Secondary Atmosphere and Possible Sulfur Species on L98-59 d from JWST Nirspec G395H Transmission Spectroscopy
Sing, David K.; Espinoza, Néstor; Crouzet, Nicolas +10 more
L 98-59 d is a Super-Earth planet orbiting an M-type star. We performed retrievals on the transmission spectrum of L 98-59 d obtained using NIRSpec G395H during a single transit, from JWST Cycle 1 GTO 1224. The wavelength range of this spectrum allows us to detect the presence of several atmospheric species. We found that the spectrum is consisten…
The tangled warp of the Milky Way
McMillan, Paul J.; Jónsson, Viktor Hrannar
Aims: We aim to determine the influence of the Milky Way's warp on the kinematics of stars across the disc, and therefore measure its precession rate and line of nodes under different assumptions.
Methods: We applied Jeans' first equation to a model of a rigidly precessing warp. The predictions of these models were fitted to the average …
Gravitational instability in a planet-forming disk
Dong, Ruobing; Tang, Ya-Wen; Teague, Richard +7 more
The canonical theory for planet formation in circumstellar disks proposes that planets are grown from initially much smaller seeds1–5. The long-considered alternative theory proposes that giant protoplanets can be formed directly from collapsing fragments of vast spiral arms6–11 induced by gravitational instability12–14<…
The POKEMON Speckle Survey of Nearby M Dwarfs. II. Observations of 1125 Targets
Hartman, Zachary D.; Ciardi, David R.; Lund, Michael B. +7 more
Stellar multiplicity is correlated with many stellar properties, yet multiplicity measurements have proven difficult for the M dwarfs—the most common type of star in our galaxy—due to their faintness and the fact that a reasonably complete inventory of later M dwarfs did not exist until recently. We have therefore carried out the Pervasive Overvie…
Chemical abundances along the quasar main sequence
Marziani, P.; del Olmo, A.; Czerny, B. +5 more
Context. The main sequence of quasars has emerged as a powerful tool for organizing the observational and physical characteristics of type-1 active galactic nuclei (AGNs). Aims. In this study, we present a comprehensive analysis of the metallicity of the gas in the broad-line region, incorporating both new data and previously published findings, t…
Insights into star formation and dispersal from the synchronization of stellar clocks
Alves, João; Barrado, David; Burkert, Andreas +3 more
Age is one of the most fundamental parameters of a star, yet it is one of the hardest to determine as it requires modelling various aspects of stellar formation and evolution. When we compare the ages derived from isochronal and dynamical traceback methods for six young stellar associations, we find a systematic discrepancy. Specifically, dynamica…
ALMA-IMF: XV. Core mass function in the high-mass star formation regime
Galván-Madrid, R.; Cunningham, N.; Braine, J. +38 more
The stellar initial mass function (IMF) is critical to our understanding of star formation and the effects of young stars on their environment. On large scales, it enables us to use tracers such as UV or Hα emission to estimate the star formation rate of a system and interpret unresolved star clusters across the Universe. So far, there is little f…
Evidence for non-zero turbulence in the protoplanetary disc around IM Lup
Hughes, A. Meredith; Wilner, David J.; Kóspál, Ágnes +6 more
The amount of turbulence in protoplanetary discs around young stars is critical for determining the efficiency, timeline, and outcomes of planet formation. It is also difficult to measure. Observations are still limited, but direct measurements of the non-thermal, turbulent gas motion are possible with the Atacama Large Millimeter/submillimeter Ar…
JWST's PEARLS: 119 multiply imaged galaxies behind MACS0416, lensing properties of caustic crossing galaxies, and the relation between halo mass and number of globular clusters at z = 0.4
Grogin, Norman A.; Koekemoer, Anton M.; Pirzkal, Nor +26 more
We present a new lens model for the ɀ = 0.396 galaxy cluster MACS J0416.1 –2403 based on a previously known set of 77 spectroscop-ically confirmed, multiply imaged galaxies plus an additional set of 42 candidate multiply imaged galaxies from past HST and new JWST data. The new galaxies lack spectroscopic redshifts but have geometric and/or photome…