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Planet(esimal)s around stars with TESS (PAST) III: A search for triplet He I in the atmospheres of two 200 Myr-old planets
Tamura, Motohide; Gaidos, Eric; Hirano, Teruyuki +13 more
We report a search for excess absorption in the 1083.2 nm line of ortho (triplet) helium during transits of TOI-1807b and TOI-2076b, 1.25 and 2.5-R⊕ planets on 0.55- and 10.4-d orbits around nearby ~200 Myr-old K dwarf stars. We limit the equivalent width of any transit-associated absorption to <4 and <8 mÅ, respectively. We limit…
Connecting photometric and spectroscopic granulation signals with CHEOPS and ESPRESSO
Alonso, R.; Deleuil, M.; Erikson, A. +83 more
Context. Stellar granulation generates fluctuations in photometric and spectroscopic data whose properties depend on the stellar type, composition, and evolutionary state. Characterizing granulation is key for understanding stellar atmospheres and detecting planets.
Aims: We aim to detect the signatures of stellar granulation, link spectrosco…
Similarity between Compact Extremely Red Objects Discovered with JWST in Cosmic Dawn and Blue-excess Dust-obscured Galaxies Known in Cosmic Noon
Inoue, Akio K.; Toba, Yoshiki; Nagao, Tohru +2 more
Spatially compact objects with extremely red color in the rest-frame optical to near-infrared (0.4-1 µm) and blue color in the rest-frame ultraviolet (UV; 0.2-0.4 µm) have been discovered at 5 < z < 9 using the James Webb Space Telescope (JWST). These extremely red objects (JWST-EROs) exhibit spectral energy distributions (SEDs) …
Identifying Tidal Disruption Events with an Expansion of the FLEET Machine-learning Algorithm
Villar, V. Ashley; van Velzen, Sjoert; Gezari, Suvi +5 more
We present an expansion of FLEET, a machine-learning algorithm optimized to select transients that are most likely tidal disruption events (TDEs). FLEET is based on a random forest algorithm trained on both the light curves and host galaxy information of 4779 spectroscopically classified transients. We find that for transients with a probability o…
The evolution of the Milky Way's thin disc radial metallicity gradient with K2 asteroseismic ages
Chiappini, Cristina; Mackereth, J. Ted; Miglio, Andrea +8 more
The radial metallicity distribution of the Milky Way's disc is an important observational constraint for models of the formation and evolution of our Galaxy. It informs our understanding of the chemical enrichment of the Galactic disc and the dynamical processes therein, particularly radial migration. We investigate how the metallicity changes wit…
Observational constraints on the origin of the elements - VII. NLTE analysis of Y II lines in spectra of cool stars and implications for Y as a Galactic chemical clock
Bergemann, Maria; Storm, Nicholas
Yttrium (Y), a key s-process element, is commonly used in nucleosynthesis studies and as a Galactic chemical clock when combined with magnesium (Mg). We study the applicability of the previously assumed local thermal equilibrium (LTE) line formation assumption in Y abundance studies of main-sequence and red giant stars, and probe the impact of NLT…
Dwarf galaxy archaeology from chemical abundances and star-formation histories
Conroy, Charlie; Ting, Yuan-Sen; Cargile, Phillip A. +8 more
We model the stellar abundances and ages of two disrupted dwarf galaxies in the Milky Way stellar halo: Gaia-Sausage Enceladus (GSE) and Wukong/LMS-1. Using a statistically robust likelihood function, we fit one-zone models of galactic chemical evolution with exponential infall histories to both systems, deriving e-folding time-scales of τin<…
Evidence That the Occurrence Rate of Hot Jupiters around Sun-like Stars Decreases with Stellar Age
Miyazaki, Shota; Masuda, Kento
We investigate how the occurrence rate of giant planets (minimum mass > 0.3 M Jup) around Sun-like stars depends on the age, mass, and metallicity of their host stars. We develop a hierarchical Bayesian framework to infer the number of planets per star (NPPS) as a function of both planetary and stellar parameters. The framework fully…
Cataclysmic Variables from Sloan Digital Sky Survey - V. The search for period bouncers continues
Hermes, J. J.; Breedt, E.; Roman-Lopes, A. +25 more
SDSS-V is carrying out a dedicated survey for white dwarfs, single, and in binaries, and we report the analysis of the spectroscopy of 118 cataclysmic variables (CVs) and CV candidates obtained during the final plug plate observations of SDSS. We identify eight new CVs, spectroscopically confirm 53 and refute 11 published CV candidates, and we rep…
ISPY: NACO Imaging Survey for Planets around Young stars. The demographics of forming planets embedded in protoplanetary disks
Quanz, S. P.; Quirrenbach, A.; Henning, T. +11 more
Context. Planet formation is a frequent process, but little observational constraints exist about the mechanisms involved, especially for giant planets at large separation. The NaCo-ISPY large program is a 120 night L'-band direct imaging survey aimed at investigating the giant planet population on wide orbits (a > 10 au) around stars hosting d…