Search Publications
Orbiting Clouds of Material at the Keplerian Co-rotation Radius of Rapidly Rotating Low-mass WTTs in Upper Sco
Pinsonneault, Marc; Cody, Ann Marie; Rebull, Luisa +8 more
Using K2 data, we identified 23 very-low-mass members of the ρ Oph and Upper Scorpius star-forming region as having periodic photometric variability not easily explained by well-established physical mechanisms such as star spots, eclipsing binaries, or pulsation. All of these unusual stars are mid-to-late M dwarfs without evidence of active accret…
Modeling the Historical Flux of Planetary Impactors
Nesvorný, David; Roig, Fernando; Bottke, William F.
The impact cratering record of the Moon and the terrestrial planets provides important clues about the formation and evolution of the solar system. Especially intriguing is the epoch ≃3.8-3.9 Gyr ago (Ga), known as the Late Heavy Bombardment (LHB), when the youngest lunar basins such as Imbrium and Orientale formed. The LHB was suggested to origin…
Small Jupiter Trojans Survey with the Subaru/Hyper Suprime-Cam
Terai, Tsuyoshi; Yoshida, Fumi
We observed the L4 Jupiter Trojans (JTs) swarm using the Hyper Suprime-Cam attached to the 8.2 m Subaru Telescope on 2015 March 30 (UT). The survey covered ∼26 deg2 of sky area near the opposition and around the ecliptic plane with a 240 s exposure time in the r-band filter through the entire survey. We detected 631 L4 JTs in the survey…
The Pan-Pacific Planet Search. VII. The Most Eccentric Planet Orbiting a Giant Star
Marshall, J. P.; Mustill, A. J.; Kane, Stephen R. +9 more
Radial velocity observations from three instruments reveal the presence of a 4 MJup planet candidate orbiting the K giant HD 76920. HD 76920b has an orbital eccentricity of 0.856 ± 0.009, making it the most eccentric planet known to orbit an evolved star. There is no indication that HD 76920 has an unseen binary companion, suggesting a …
Revision of Stellar Intrinsic Colors in the Infrared by Spectroscopic Surveys
Jiang, Biwei; Zhao, He; Gao, Shuang +1 more
Intrinsic colors of normal stars are derived in the popularly used infrared bands involving the Two Micron All-Sky Survey/JHKS, Wide-field Infrared Survey Explorer, Spitzer/IRAC, and AKARI/S9W filters. Based on three spectroscopic surveys—LAMOST, RAVE, and APOGEE, stars are classified into groups of giants and dwarfs, as well as metal-n…
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…
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…
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…
Thermal Modeling of Comet-like Objects from AKARI Observation
Usui, Fumihiko; Ishiguro, Masateru; Bach, Yoonsoo P.
We investigated the physical properties of the comet-like objects 107P/(4015) Wilson-Harrington (4015WH) and P/2006 HR30 (Siding Spring; HR30) by applying a simple thermophysical model to the near-infrared spectroscopy and broadband observation data obtained by the AKARIsatellite of JAXA when they showed no detectable comet-like activity. We selec…
Point and Compact Hα Sources in the Interior of M33
Joner, Michael D.; Roming, Peter W. A.; Hintz, Eric G. +2 more
A variety of interesting objects such as Wolf-Rayet stars, tight OB associations, planetary nebulae, X-ray binaries, etc., can be discovered as point or compact sources in Hα surveys. How these objects distribute through a galaxy sheds light on the galaxy star formation rate and history, mass distribution, and dynamics. The nearby galaxy M33 is an…