176 citations · 1.6k across the 58 of their papers we have counts for
59 papers
COUNTESS I: A Uniformly Vetted Catalog of Known and New Transiting Exoplanets in the TESS Northern Continuous Viewing Zone
Andrew Hotnisky, Rachel B. Fernandes, Kevin K. Hardegree-Ullman +9
The Transiting Exoplanet Survey Satellite (TESS) has transformed the study of nearby exoplanetary systems; however, its nominal observing strategy limits sensitivity to planets wit…
A Spitzer Space Telescope Exploration Science Program to Search for Y Dwarf Variability
Michael C. Cushing, Jesica L. Trucks, Kevin K. Hardegree-Ullman +10
We present the results of a Spitzer Space Telescope Exploration Science Program to search for and characterize variability in Y dwarfs. We observed 14 Y dwarfs over a 24 hr period…
Exoplanets in ancient stellar populations: occurrence constraints and hot-Jupiter candidates in the Galactic halo
Dolev Bashi, Michelle Kunimoto, Kevin K. Hardegree-Ullman +3
The Galactic halo preserves a record of the Milky Way's earliest assembly and contains both in-situ stars and stars accreted from dwarf galaxies. Possible planets around these star…
Gaia DR3 IDs for TESS Input Catalog Targets
Kevin K. Hardegree-Ullman, Melanie Swain, Jessie L. Christiansen +6
The TESS Input Catalog (TIC) was built on Gaia Data Release 2 (DR2). To date, there has not been an update to the TIC to incorporate Gaia Data Release 3 (DR3) IDs. In this Research…
Modeling the Impact of Unresolved Stellar Companions on Detection Sensitivity in Kepler's Small Planet Occurrence Rates
Galen J. Bergsten, David R. Ciardi, Jessie L. Christiansen +5
Unresolved stellar companions can cause both under-estimations in the radii of transiting planets and over-estimations of their detectability, affecting our ability to reliably mea…
Bioverse: Assessing the Ability of Direct Imaging Surveys to Empirically Constrain the Habitable Zone via Trends in Albedo
Noah W. Tuchow, Christopher C. Stark, Daniel Apai +2
Will future direct imaging missions such as NASA's upcoming Habitable Worlds Observatory (HWO) be able to understand Earth-sized planets as a population? In this study, we simulate…
Scaling K2 VIII: Short-Period Sub-Neptune Occurrence Rates Peak Around Early-Type M Dwarfs
Kevin K. Hardegree-Ullman, Galen J. Bergsten, Jessie L. Christiansen +6
We uniformly combined data from the NASA Kepler and K2 missions to compute planet occurrence rates across the entire FGK and M dwarf stellar range. The K2 mission, driven by target…
The NASA Exoplanet Archive and Exoplanet Follow-up Observing Program: Data, Tools, and Usage
Jessie L. Christiansen, Douglas L. McElroy, Marcy Harbut +17
The NASA Exoplanet Archive and the Exoplanet Follow-up Observing Program service are two widely used resources for the exoplanet community. The NASA Exoplanet Archive provides a co…
Bioverse: Potentially Observable Exoplanet Biosignature Patterns Under the UV Threshold Hypothesis for the Origin of Life
Martin Schlecker, Dániel Apai, Antonin Affholder +5
A wide variety of scenarios for the origin of life have been proposed, with many influencing the prevalence and distribution of biosignatures across exoplanet populations. This rel…
Signatures of Atmospheric Mass Loss and Planet Migration in the Time Evolution of Short-Period Transiting Exoplanets
Rachel B. Fernandes, Galen J. Bergsten, Gijs D. Mulders +19
Comparative studies of young and old exoplanet populations offer a glimpse into how planets may form and evolve with time. We present an occurrence rate study of short-period (1…
Planet Masses, Radii, and Orbits from NASA's K2 Mission
Andrew W. Howard, Evan Sinukoff, Sarah Blunt +50
We report the masses, sizes, and orbital properties of 86 planets orbiting 55 stars observed by NASA's K2 Mission with follow-up Doppler measurements by the HIRES spectrometer at t…
GEMS JWST: Transmission spectroscopy of TOI-5205b reveals significant stellar contamination and a metal-poor atmosphere
Caleb I. Cañas, Jacob Lustig-Yaeger, Shang-Min Tsai +21
Recent discoveries of transiting giant exoplanets () around M dwarfs (GEMS) present an opportunity to investigate their atmospheric compositions and…
The Palomar twilight survey of 'Ayló'chaxnim, Atiras, and comets
B. T. Bolin, F. J. Masci, M. W. Coughlin +29
Near-sun sky twilight observations allow for the detection of asteroid interior to the orbit of Venus (Aylos), the Earth (Atiras), and comets. We present the results of observation…
The First Evidence of a Host Star Metallicity Cut-off In The Formation of Super-Earth Planets
Kiersten M. Boley, Jessie L. Christiansen, Jon Zink +7
Planet formation is expected to be severely limited in disks of low metallicity, owing to both the small solid mass reservoir and the low opacity accelerating the disk gas dissipat…
New ephemerides and detection of transit-timing variations in the K2-138 system using high-precision CHEOPS photometry
H. G. Vivien, S. Hoyer, M. Deleuil +5
Multi-planet systems are a perfect laboratory for constraining planetary formation models. A few of these systems present planets that come very close to mean motion resonance, pot…
Bioverse: GMT and ELT Direct Imaging and High-Resolution Spectroscopy Assessment $\unicode{x2013}$ Surveying Exo-Earth O and Testing the Habitable Zone Oxygen Hypothesis
Kevin K. Hardegree-Ullman, Dániel Apai, Sebastiaan Y. Haffert +4
Biosignature detection in the atmospheres of Earth-like exoplanets is one of the most significant and ambitious goals for astronomy, astrobiology, and humanity. Molecular oxygen is…
Metallicities and Refined Stellar Parameters for 52 Cool Dwarfs with Transiting Planets and Planet Candidates
Rebecca Gore, Steven Giacalone, Courtney D. Dressing +8
We collected near-infrared spectra of 65 cool stars with the NASA InfraRed Telescope Facility (IRTF) and analyze them to calculate accurate metallicities and stellar parameters. Th…
A Reply to: Large Exomoons unlikely around Kepler-1625 b and Kepler-1708 b
David Kipping, Alex Teachey, Daniel A. Yahalomi +7
Recently, Heller & Hippke argued that the exomoon candidates Kepler-1625 b-i and Kepler-1708 b-i were allegedly 'refuted'. In this Matters Arising, we address these claims. For Kep…
Scaling K2 VII: Evidence for a high occurrence rate of hot sub-Neptunes at intermediate ages
Jessie L. Christiansen, Jon K. Zink, Kevin K. Hardegree-Ullman +6
The NASA K2 mission obtained high precision time-series photometry for four young clusters, including the near-twin 600-800 Myr-old Praesepe and Hyades clusters. Hot sub-Neptunes a…
No Evidence for More Earth-sized Planets in the Habitable Zone of Kepler's M versus FGK Stars
Galen J. Bergsten, Ilaria Pascucci, Kevin K. Hardegree-Ullman +3
Reliable detections of Earth-sized planets in the habitable zone remain elusive in the Kepler sample, even for M dwarfs. The Kepler sample was once thought to contain a considerabl…
Clouds and Clarity: Revisiting Atmospheric Feature Trends in Neptune-size Exoplanets
Jonathan Brande, Ian J. M. Crossfield, Laura Kreidberg +12
Over the last decade, precise exoplanet transmission spectroscopy has revealed the atmospheres of dozens of exoplanets, driven largely by observatories like the Hubble Space Telesc…
Water absorption in the transmission spectrum of the water-world candidate GJ9827d
Pierre-Alexis Roy, Björn Benneke, Caroline Piaulet +16
Recent work on the characterization of small exoplanets has allowed us to accumulate growing evidence that the sub-Neptunes with radii greater than often host H…
Bioverse: The Habitable Zone Inner Edge Discontinuity as an Imprint of Runaway Greenhouse Climates on Exoplanet Demographics
Martin Schlecker, Dániel Apai, Tim Lichtenberg +3
Long-term magma ocean phases on rocky exoplanets orbiting closer to their star than the runaway greenhouse threshold - the inner edge of the classical habitable zone - may offer in…
Using Photometrically-Derived Properties of Young Stars to Refine TESS's Transiting Young Planet Survey Completeness
Rachel B. Fernandes, Kevin K. Hardegree-Ullman, Ilaria Pascucci +7
The demographics of young exoplanets can shed light onto their formation and evolution processes. Exoplanet properties are derived from the properties of their host stars. As such,…