Search Publications
X-Rays from e ± Pair Halos
Ruffolo, D.; Luangtip, W.; Eungwanichayapant, A. +1 more
It was previously suggested that e ± pair halos could be observed in γ-rays. Searching for pair halos is a challenging topic in γ-ray astronomy that has not yet yielded a convincing detection for an individual object. Here we propose that X-ray observations could reveal the existence of e ± pair halos. To support our suggesti…
No Pulsar Wind Nebula in the Southern Blowout Region of the Cygnus Loop
Gotthelf, E. V.; Halpern, J. P.
We report on optical observations of the Katsuda et al. candidate X-ray pulsar and pulsar wind nebula in the Cygnus Loop supernova remnant. We determine that the point source suggested to be a pulsar is actually the nucleus of a Seyfert 1 galaxy at redshift z = 0.2080, while the diffuse X-ray source, which is displaced by 2.‧6 from the point sourc…
The Modulating Optical Depth of the Photoelectric Absorption Edge with a Pulse Phase in Accretion-powered X-Ray Pulsars
Kitamoto, Shunji; Yoshida, Yuki
We report the first discovery of a pulse phase modulating optical depths at the iron K-edge in accretion-powered X-ray pulsars from Suzaku observations. A significant modulating optical depth of the iron K-edge is detected for Vela X-1 and GX 1+4. Similar trends are seen in GX 301-2 and OAO 1657-415, though with poor statistical significance. The …
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…