Search Publications
Scaling K2. VI. Reduced Small-planet Occurrence in High-galactic-amplitude Stars
Rice, Malena; Howard, Andrew W.; Petigura, Erik A. +13 more
In this study, we performed a homogeneous analysis of the planets around FGK dwarf stars observed by the Kepler and K2 missions, providing spectroscopic parameters for 310 K2 targets -including 239 Scaling K2 hosts-observed with Keck/HIRES. For orbital periods less than 40 days, we found that the distribution of planets as a function of orbital pe…
A Multiwavelength Study of Active Galactic Nuclei in Post-merger Remnants
Li, Wenhao; Ryan, Russell; Drory, Niv +9 more
We investigate the role of galaxy mergers in triggering active galactic nuclei (AGN) in the nearby universe. Our analysis is based on a sample of 79 post-merger remnant galaxies with deep X-ray observations from Chandra/XMM-Newton capable of detecting a low-luminosity AGN of ≥1040.5 erg s-1. This sample is derived from a visu…
55 Cancri e's occultation captured with CHEOPS
Alonso, R.; Deleuil, M.; Erikson, A. +73 more
Past occultation and phase-curve observations of the ultra-short period super-Earth 55 Cnc e obtained at visible and infrared wavelengths have been challenging to reconcile with a planetary reflection and emission model. In this study, we analyse a set of 41 occultations obtained over a two-year timespan with the CHEOPS satellite. We report the de…
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<…