Search Publications
Radial Velocities of Low-mass Candidate TWA Members
Mace, Gregory; Sokal, Kimberly; Kidder, Benjamin +2 more
Nearby young moving groups provide unique samples of similar age stars for testing the evolution of physical properties. Incomplete and/or incorrect group membership classifications reduce the usefulness of the group, which we assume to be coeval. With near-infrared spectra of two candidate members of the TW Hya Association, 2MASS J12354615-411553…
Detection of Crystalline and Fine-grained Calcic Plagioclases on Vesta
Aoki, S.; Oliva, F.; D'Aversa, E. +8 more
Plagioclase feldspars are among the most prevalent minerals in the solar system, and are present in many chondritic and achondritic meteorite families. Nevertheless, spectral features of plagioclases have never been unambiguously and directly observed in remote observations of asteroids. We report here the detection of an absorption band at 12.2 &…
A Hint of Three-section Halo As Seen from the APOGEE DR14
Zhao, G.; Chen, Y. Q.; Xue, X. X. +4 more
Based on the [M/H] versus [Mg/Fe] diagram and distances from APOGEE data release 14, we compare the spatial distributions, the l - V los diagram, and the abundance gradients between high-[Mg/Fe] and low-[Mg/Fe] sequences. The two sequences are clearly shown at 5< | Z| < 10 {kpc} in the metallicity range of -1.6 < [M/H] < -0.…
Estimates of the Atmospheric Escape Rates of CH4 from Titan
Ip, Wing-Huen; Hsu, Jen-Kai
The upper atmosphere of Titan is highly variable as characterized by the variations of the thermospheric and exospheric temperatures from in situ measurements by Cassini at different Titan encounters. A related question has to do with the escape flux of CH4 that might also change with the complex plasma environment and ionospheric condi…
Opposite Polarity Magnetic Fields and Convective Downflows in a Simulated Sunspot Penumbra
Rempel, Matthias; Bharti, Lokesh
Recent numerical simulations and observations of sunspots show a significant amount of opposite polarity magnetic fields within the sunspot penumbra. Most of the opposite polarity fields are associated with convective downflows. We present an analysis of 3D MHD simulations through forward modeling of synthetic Stokes profiles of the Fe I 6301.5 Å …
Effect of the Surface Roughness of Icy Grains on Molecular Oxygen Chemistry in Molecular Clouds
Gunell, H.; De Keyser, J.; Mousis, O. +6 more
Molecular cloud and protosolar nebula chemistry involves a strong interaction between the gas phase and the surface of icy grains. The exchanges between the gas phase and the solid phase depend not only on the adsorption and desorption rates but also on the geometry of the surface of the grains. Indeed, for sufficient levels of surface roughness, …
Northern Galactic Molecular Cloud Clumps in Hi-GAL: Clump and Star Formation within Clouds
Rosolowsky, Erik; Zetterlund, Erika; Glenn, Jason
We investigate how the properties of Galactic giant molecular clouds (GMCs) and their denser substructures (clumps) correlate with the local star formation rate (SFR). We trace clouds using the 12CO(3-2) transition, as observed by the CO High Resolution Survey. We identify their constituent clumps using thermal dust emission, as observe…
A Kinematically Cold Structure of Candidate Young OB Stars toward the Anticenter
Casetti-Dinescu, Dana I.; Girard, Terrence M.
We combine Galaxy Evolution Explorer and Gaia DR2 catalogs to track star formation in the outskirts of our Galaxy. Using photometry, proper motions, and parallaxes we identify a structure of ∼300 OB-type candidates located between 12 and 15 kpc from the Galactic center that are kinematically cold. The structure is located between l = 120° and 200°…
Probing the Bardeen-Petterson Effect in Tidal Disruption Events with Spectral line Reverberation Mapping
Dovčiak, Michal; Zhang, Wenda; Karas, Vladimír +1 more
For an inclined accretion flow around a rotating black hole, the combined effect of the Lense-Thirring precession and viscous torque tends to align the inner part of the flow with the black hole spin, leading to the formation of a warped disk, known as the Bardeen-Petterson (BP) effect. In tidal disruption events (TDEs) in which a supermassive bla…
Size Scaling of Clump Instabilities in Turbulent, Feedback-regulated Disks
Glazebrook, Karl; Fisher, Deanne B.; Obreschkow, Danail +5 more
We explore the scaling between the size of star-forming clumps and rotational support in massively star-forming galactic disks. The analysis relies on simulations of a clumpy galaxy at z = 2 and the observed DYnamics of Newly Assembled Massive Objects (DYNAMO) sample of rare clumpy analogs at z ≈ 0.1 to test a predictive clump size scaling propose…