Search Publications
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.…
The First Habitable-zone Earth-sized Planet from TESS. II. Spitzer Confirms TOI-700 d
Barclay, Thomas; Vanderburg, Andrew; Latham, David W. +43 more
We present Spitzer 4.5 µm observations of the transit of TOI-700 d, a habitable-zone Earth-sized planet in a multiplanet system transiting a nearby M-dwarf star (TIC 150428135, 2MASS J06282325-6534456). TOI-700 d has a radius of ${1.144}_{-0.061}^{+0.062}{R}_{\oplus }$ and orbits within its host star's conservative habitable zone with a peri…
The Dynamics of Interstellar Asteroids and Comets within the Galaxy: An Assessment of Local Candidate Source Regions for 1I/'Oumuamua and 2I/Borisov
Hallatt, Tim; Wiegert, Paul
The low velocity of interstellar asteroid 1I/'Oumuamua with respect to our galaxy's local standard of rest implies that it is young. Adopting the young age hypothesis, we assess possible origin systems for this interstellar asteroid and for 2I/Borisov, though the latter's higher speed means it is unlikely to be young. First, their past trajectorie…