Search Publications
Constraints on Metastable Helium in the Atmospheres of WASP-69b and WASP-52b with Ultranarrowband Photometry
Tinyanont, Samaporn; Millar-Blanchaer, Maxwell A.; Knutson, Heather A. +7 more
Infrared observations of metastable 23S helium absorption with ground- and space-based spectroscopy are rapidly maturing, as this species is a unique probe of exoplanet atmospheres. Specifically, the transit depth in the triplet feature (with vacuum wavelengths near 1083.3 nm) can be used to constrain the temperature and mass-loss rate …
Keck Observations Confirm a Super-Jupiter Planet Orbiting M Dwarf OGLE-2005-BLG-071L
Lu, Jessica R.; Cole, Andrew A.; Udalski, Andrzej +10 more
We present adaptive optics imaging from the NIRC2 instrument on the Keck II telescope that resolves the exoplanet host (and lens) star as it separates from the brighter source star. These observations yield the K-band brightness of the lens and planetary host star, as well as the lens-source relative proper motion, ${{\boldsymbol{\mu }}}_{\mathrm{…
Obliquity Constraints on an Extrasolar Planetary-mass Companion
Knutson, Heather A.; Morley, Caroline V.; Bowler, Brendan P. +8 more
We place the first constraints on the obliquity of a planetary-mass companion outside of the solar system. Our target is the directly imaged system 2MASS J01225093-2439505 (2M0122), which consists of a 120 Myr 0.4 M⊙ star hosting a 12-27 MJ companion at 50 au. We constrain all three of the system's angular-momentum vectors: h…
Spectral Variability of VHS J1256-1257b from 1 to 5 µm
Kataria, Tiffany; Apai, Dániel; Zhou, Yifan +4 more
Multiwavelength time-resolved observations of rotationally modulated variability from brown dwarfs and giant exoplanets are the most effective method for constraining their heterogeneous atmospheric structures. In a companion paper, we reported the discovery of strong near-infrared variability in HST/WFC3/G141 light curves of the very red L-dwarf …
An Extreme-precision Radial-velocity Pipeline: First Radial Velocities from EXPRES
Ong, J. M. Joel; Fischer, Debra A.; Buchhave, Lars A. +13 more
The EXtreme-PREcision Spectrograph (EXPRES) is an environmentally stabilized, fiber-fed, R = 137,500, optical spectrograph. It was recently commissioned at the 4.3 m Lowell Discovery Telescope near Flagstaff, Arizona. The spectrograph was designed with a target radial-velocity (RV) precision of 30 cm s-1. In addition to instrumental inn…
Two Views of the Radius Gap and the Role of Light Curve Fitting
Petigura, Erik A.
Recently, several groups have resolved a gap that bifurcates planets between the size of Earth and Neptune into two populations. The location and depth of this feature is an important signature of the physical processes that form and sculpt planets. In particular, planets residing in the radius gap are valuable probes of these processes as they ma…
Performance Verification of the EXtreme PREcision Spectrograph
Ong, J. M. Joel; Fischer, Debra A.; Buchhave, Lars A. +22 more
The EXtreme PREcision Spectrograph (EXPRES) is a new Doppler spectrograph designed to reach a radial-velocity measurement precision sufficient to detect Earth-like exoplanets orbiting nearby, bright stars. We report on extensive laboratory testing and on-sky observations to quantitatively assess the instrumental radial-velocity measurement precisi…
Revisiting MOA 2013-BLG-220L: A Solar-type Star with a Cold Super-Jupiter Companion
Cole, Andrew A.; Beaulieu, Jean-Philippe; Bond, Ian A. +7 more
We present the analysis of high-resolution images of MOA-2013-BLG-220, taken with the Keck adaptive optics system six years after the initial observation, identifying the lens as a solar-type star hosting a super-Jupiter-mass planet. The masses of planets and host stars discovered by microlensing are often not determined from light-curve data, whi…
Exploring the Evolution of Stellar Rotation Using Galactic Kinematics
Angus, Ruth; Foreman-Mackey, Daniel; van Saders, Jennifer +9 more
The rotational evolution of cool dwarfs is poorly constrained after ∼1-2 Gyr due to a lack of precise ages and rotation periods for old main-sequence stars. In this work, we use velocity dispersion as an age proxy to reveal the temperature-dependent rotational evolution of low-mass Kepler dwarfs and demonstrate that kinematic ages could be a usefu…
Into the UV: A Precise Transmission Spectrum of HAT-P-41b Using Hubble's WFC3/UVIS G280 Grism
Wakeford, H. R.; Sing, D. K.; Nikolov, N. +8 more
The ultraviolet-visible wavelength range holds critical spectral diagnostics for the chemistry and physics at work in planetary atmospheres. To date, time-series studies of exoplanets to characterize their atmospheres have relied on several combinations of modes on the Hubble Space Telescope's STIS/COS instruments to access this wavelength regime.…