Search Publications
Gaia-based Isochronal, Kinematic, and Spatial Analysis of the ɛ Cha Association
Kastner, Joel H.; Dickson-Vandervelde, D. Annie; Wilson, Emily C.
The precise parallax, proper motion, and photometric measurements contained in Gaia Data Release 2 (DR2) offer the opportunity to reexamine the membership and ages of nearby young moving groups (NYMGs), i.e., loose groups of stars of age ≲100 Myr in the solar vicinity. Here, we analyze the available DR2 data for members and candidate members of th…
Relative Ages of Nine Inner Milky Way Globular Clusters from Proper-motion-cleaned Color-Magnitude Diagrams
Brown, Thomas M.; Cohen, Roger E.; Casagrande, Luca +3 more
Our picture of the age-metallicity relation for Milky Way globular clusters (MWGCs) is still highly incomplete, and the majority of MWGCs lack self-consistent age measurements. Here, we exploit deep, homogenous multiepoch Hubble Space Telescope imaging of nine MWGCs located toward the inner Milky Way to measure their relative ages, in most cases f…
Physical Parameters of the Multiplanet Systems HD 106315 and GJ 9827
Gorjian, Varoujan; Mayo, Andrew W.; Rice, Malena +42 more
HD 106315 and GJ 9827 are two bright, nearby stars that host multiple super-Earths and sub-Neptunes discovered by K2 that are well suited for atmospheric characterization. We refined the planets' ephemerides through Spitzer transits, enabling accurate transit prediction required for future atmospheric characterization through transmission spectros…
Inner and Outer Orbits in 13 Resolved Hierarchical Stellar Systems
Tokovinin, A.
Orbits of inner and outer subsystems in 13 triple or higher-order stellar systems are computed or updated using position measurements and, in three cases, radial velocities. The goal is to determine mutual orbital inclinations, period ratios, and masses to complement the statistics of hierarchical systems. The effect of the subsystems on the motio…
Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Yr, Highly Eccentric Orbit
Esposito, Thomas M.; Kane, Stephen R.; Rosenthal, Lee J. +13 more
Radial velocity (RV) surveys have discovered giant exoplanets on au-scale orbits with a broad distribution of eccentricities. Those with the most eccentric orbits are valuable laboratories for testing theories of high-eccentricity migration. However, few such exoplanets transit their host stars, thus removing the ability to apply constraints on fo…
Precision Millimeter Astrometry of the α Centauri AB System
Kervella, Pierre; Beichman, Charles; Benedict, G. Fritz +2 more
Alpha Centauri A is the closest solar-type star to the Sun and offers the best opportunity to find and ultimately to characterize an Earth-sized planet located in its habitable zone. Here, we describe initial results from an Atacama Large Millimeter/submillimeter Array (ALMA) program to search for planets in the α Cen AB system using differential …
Structure and Internal Kinematics of Nine Inner Milky Way Globular Clusters
Brown, Thomas M.; Cohen, Roger E.; Bellini, Andrea +3 more
This study constitutes part of a larger effort aimed at better characterizing the Galactic globular clusters (GGCs) located toward the inner Milky Way bulge and disk. Here, we focus on internal kinematics of nine GGCs, obtained from space-based imaging over time baselines of >9 yr. We exploit multiple avenues to assess the dynamical state of th…
The High-energy Spectrum of the Nearby Planet-hosting Inactive Mid-M Dwarf LHS 3844
Youngblood, Allison; Charbonneau, David; Kempton, Eliza M. -R. +5 more
To fully characterize the atmospheres, or lack thereof, of terrestrial exoplanets, we must include the high-energy environments provided by their host stars. The nearby mid-M dwarf LHS 3844 hosts a terrestrial world that lacks a substantial atmosphere. We present a time-series UV spectrum of LHS 3844 from 1131 to 3215 Å captured by HST/COS. We det…
Higher Compact Multiple Occurrence around Metal-poor M-dwarfs and Late-K-dwarfs
Bedell, Megan; Dittmann, Jason A.; Ballard, Sarah +1 more
The planet-metallicity correlation serves as a potential link between exoplanet systems as we observe them today and the effects of bulk composition on the planet formation process. Many observers have noted a tendency for Jovian planets to form around stars with higher metallicities; however, there is no consensus on a trend for smaller planets. …
The Epoch of Giant Planet Migration Planet Search Program. I. Near-infrared Radial Velocity Jitter of Young Sun-like Stars
Cochran, William D.; Endl, Michael; Mahadevan, Suvrath +8 more
We present early results from the Epoch of Giant Planet Migration program, a precise radial velocity (RV) survey of more than 100 intermediate-age (∼20-200 Myr) G and K dwarfs with the Habitable Zone Planet Finder spectrograph (HPF) at McDonald Observatory's Hobby-Eberly Telescope. The goals of this program are to determine the timescale and domin…