Search Publications
A Spatially Dependent Correction of Gaia EDR3 Parallax Zero-point Offset based on 0.3 million LAMOST DR8 Giant Stars
Huang, Yang; Yuan, Haibo; Wang, Chun
We have studied the zero-point offset of Gaia Early Data Release 3 (EDR3) parallaxes based on a sample of 0.3 million giant stars built from the LAMOST data with distance accuracy better than 8.5%. The official parallax zero-point corrections largely reduce the global offset in the Gaia EDR3 parallaxes: the global parallax offsets are -27.9 µ…
Hitting a New Low: The Unique 28 hr Cessation of Accretion in the TESS Light Curve of YY Dra (DO Dra)
Garnavich, Peter; Littlefield, Colin; Szkody, Paula +6 more
We present the Transiting Exoplanet Surveying Satellite light curve of the intermediate polar YY Draconis (YY Dra, also known as DO Dra). The power spectrum indicates that while there is stream-fed accretion for most of the observational period, there is a day-long, flat-bottomed low state at the beginning of 2020 during which the only periodic si…
Simultaneous Detection of Optical Flares of the Magnetically Active M-dwarf Wolf359
Wang, Shiang-Yu; Zhang, Yu; Lehner, Matthew J. +13 more
We present detections of stellar flares of Wolf 359, an M6.5 dwarf in the solar neighborhood (2.41 pc) known to be prone to flares due to surface magnetic activity. The observations were carried out from 2020 April 23 to 29 with a 1 m and a 0.5 m telescope separated by nearly 300 km in Xinjiang, China. In 27 hr of photometric monitoring, a total o…
Extremely Inclined Orbit of the S-type Planet γ Cep Ab Induced by the Eccentric Kozai-Lidov Mechanism
Ji, Jianghui; Huang, Xiumin
γ Cep Ab is a typical S-type planet, which occupies a nearly perpendicular planetary orbit relative to the binary. Here, we use a Markov Chain Monte Carlo sampler to conduct a full N-body fitting and derive self-consistent orbital solutions for this hierarchical system. We then employ the eccentric Kozai-Lidov (EKL) mechanism to explain the extrem…
A New Absolute Proper Motion Determination of Leo I Using HST/WFPC2 Images and Gaia EDR3
Horch, Elliott P.; Kozhurina-Platais, Vera; Casetti-Dinescu, Dana I. +3 more
We measure the absolute proper motion of Leo I using a WFPC2/HST data set that spans up to 10 yr to date the longest time baseline utilized for this satellite. The measurement relies on ~2300 Leo I stars located near the center of light of the galaxy; the correction to absolute proper motion is based on 174 Gaia EDR3 stars and 10 galaxies. Having …
The Galactic Distribution of Phosphorus: A Survey of 163 Disk and Halo Stars
Janowiecki, Steven; Cargile, Phillip; Hawkins, Keith +3 more
Phosphorus (P) is a critical element for life on Earth, yet the cosmic production sites of P are relatively uncertain. To understand how P has evolved in the solar neighborhood, we measured abundances for 163 FGK stars over a range of -1.09 < [Fe/H] < 0.47 using observations from the Habitable-zone Planet Finder instrument on the Hobby-Eberl…
A Mid-infrared Study of Directly Imaged Planetary-mass Companions Using Archival Spitzer/IRAC Images
Kraus, Adam L.; Martinez, Raquel A.
The atmospheres and accretion disks of planetary-mass and substellar companions provide an unprecedented look into planet and moon formation processes, most notably the frequency and lifetime of circumplanetary disks. In our ongoing effort to leverage the extraordinary sensitivity of the Spitzer/Infrared Array Camera (IRAC) at 3.6, 4.5, 5.8, and 8…
The Gliese 86 Binary System: A Warm Jupiter Formed in a Disk Truncated at ≈2 au
Wittenmyer, Robert A.; Horner, Jonathan; Dupuy, Trent J. +12 more
Gliese 86 is a nearby K dwarf hosting a giant planet on a ≈16 day orbit and an outer white dwarf companion on a ≈century-long orbit. In this study we combine radial velocity data (including new measurements spanning more than a decade) with high angular resolution imaging and absolute astrometry from Hipparcos and Gaia to measure the current orbit…
A Hot Mars-sized Exoplanet Transiting an M Dwarf
Cochran, William D.; Endl, Michael; Mahadevan, Suvrath +21 more
We validate the planetary nature of an ultra-short-period planet orbiting the M dwarf KOI-4777. We use a combination of space-based photometry from Kepler, high-precision, near-infrared Doppler spectroscopy from the Habitable-zone Planet Finder, and adaptive optics imaging to characterize this system. KOI-4777.01 is a Mars-sized exoplanet (R …
Orbits of the Irregular Satellites of Uranus and Neptune
Jacobson, Robert A.; Brozović, Marina
We report on an ephemerides update for the irregular satellites of Uranus and Neptune, including Nereid. Our data set contains ground-based and Voyager 2 position measurements of the satellites. Some of the new observations were reduced with respect to the GAIA star catalog and represent high-quality, modern astrometry. The orbital fits are based …