Search Publications
Hierarchical Probabilistic Inference of the Color-Magnitude Diagram and Shrinkage of Stellar Distance Uncertainties
Leistedt, Boris; Hogg, David W.
We present a hierarchical probabilistic model for improving geometric stellar distance estimates using color-magnitude information. This is achieved with a data-driven model of the color-magnitude diagram, not relying on stellar models but instead on the relative abundances of stars in color-magnitude cells, which are inferred from very noisy magn…
Beyond 3 au from the Sun: The Hypervolatiles CH4, C2H6, and CO in the Distant Comet C/2006 W3 (Christensen)
Villanueva, Geronimo L.; Mumma, Michael J.; DiSanti, Michael A. +5 more
Comet C/2006 W3 (Christensen) remained outside a heliocentric distance (R h) of 3.1 au throughout its apparition, but it presented an exceptional opportunity to directly sense a suite of molecules released from its nucleus. The Cryogenic Infrared Echelle Spectrograph at ESO-VLT detected infrared emissions from the three “hypervolatiles”…
Infrared Spectroscopy of HR 4796A's Bright Outer Cometary Ring + Tenuous Inner Hot Dust Cloud
Sitko, M. L.; Marengo, M.; Chen, C. H. +4 more
We have obtained new NASA/IRTF SpeX spectra of the HR 4796A debris ring system. We find a unique red excess flux that extends out to ∼9 µm in Spitzer IRS spectra, where thermal emission from cold, ∼100 K dust from the system's ring at ∼75 au takes over. Matching imaging ring photometry, we find the excess consists of NIR reflectance from the…
A Six-planet System around the Star HD 34445
Butler, R. Paul; Vogt, Steven S.; Crane, Jeffrey D. +10 more
We present a new precision radial velocity (RV) data set that reveals a multi-planet system orbiting the G0V star HD 34445. Our 18-year span consists of 333 precision RV observations, 56 of which were previously published and 277 of which are new data from the Keck Observatory, Magellan at Las Campanas Observatory, and the Automated Planet Finder …
The Solar Neighborhood. XLII. Parallax Results from the CTIOPI 0.9 m Program—Identifying New Nearby Subdwarfs Using Tangential Velocities and Locations on the H-R Diagram
Henry, Todd J.; Winters, Jennifer G.; Jao, Wei-Chun +4 more
Parallaxes, proper motions, and optical photometry are presented for 51 systems consisting of 37 cool subdwarf and 14 additional high proper motion systems. Thirty-seven systems have parallaxes reported for the first time, 15 of which have proper motions of at least 1″ yr-1. The sample includes 22 newly identified cool subdwarfs within …
Size Dependence of Dust Distribution around the Earth Orbit
Kaneda, Hidehiro; Ishihara, Daisuke; Kondo, Toru +3 more
In the solar system, interplanetary dust particles (IDPs) originating mainly from asteroid collisions and cometary activities drift to Earth orbit due to Poynting-Robertson drag. We analyzed the thermal emission from IDPs that was observed by the first Japanese infrared astronomical satellite, AKARI. The observed surface brightness in the trailing…
Characterizing the Stellar Population of NGC 1980
Kounkel, Marina; Hartmann, Lee; Calvet, Nuria +1 more
NGC 1980 is a young cluster that is located about 0.°5 south of the Orion Nebula Cluster (ONC). Recent studies by Bouy et al. and Pillitteri et al. have suggested that NGC 1980 contains an older population of stars compared to a much younger ONC, and that it belongs to a foreground population that may be located in front of the Orion A molecular g…
The Faintest WISE Debris Disks: Enhanced Methods for Detection and Verification
Metchev, Stanimir A.; Heinze, Aren; Patel, Rahul I. +1 more
In an earlier study, we reported nearly 100 previously unknown dusty debris disks around Hipparcos main-sequence stars within 75 pc by selecting stars with excesses in individual WISE colors. Here, we further scrutinize the Hipparcos 75 pc sample to (1) gain sensitivity to previously undetected, fainter mid-IR excesses and (2) remove spurious exce…
Optimal Stellar Photometry for Multi-conjugate Adaptive Optics Systems Using Science-based Metrics
Massari, D.; Stetson, P. B.; Bono, G. +5 more
We present a detailed discussion of how to obtain precise stellar photometry in crowded fields using images from multi-conjugate adaptive optics (MCAO) systems, with the intent of informing the scientific development of this key technology for the Extremely Large Telescopes. We use deep J and K s exposures of NGC 1851 taken with the Gem…
The Canonical Luminous Blue Variable AG Car and Its Neighbor Hen 3-519 are Much Closer than Previously Assumed
Smith, Nathan; Stassun, Keivan G.
The strong mass loss of Luminous Blue Variables (LBVs) is thought to play a critical role in massive-star evolution, but their place in the evolutionary sequence remains debated. A key to understanding their peculiar instability is their high observed luminosities, which often depends on uncertain distances. Here we report direct distances and spa…