Search Publications
Extraplanar Gas in Edge-on Galaxies Traced by SOFIA Observations of [C II]
Reach, William T.; Fadda, Dario; Stacey, Gordon J. +1 more
Bursts of localized star formation in galaxies can levitate material from the midplane. Spiral galaxies that are edge-on allow a clear distinction of material that is levitated off the galaxies' midplanes. We used SOFIA to measure the vertical distribution of [C II] 157.7 µm line emission for two nearby, edge-on galaxies, NGC 891 and NGC 590…
Cause and Kinematics of a Jetlike CME
Wang, Yuming; Joshi, Reetika; Chandra, Ramesh +3 more
In this article, we present the multiviewpoint and multiwavelength analysis of an atypical solar jet based on data from Solar Dynamics Observatory, SOlar and Heliospheric Observatory, and Solar TErrestrial RElations Observatory. It is generally believed that coronal mass ejections (CMEs) develop from the large-scale solar eruptions in the lower at…
Shear Measurement Bias Due to Spatially Varying Spectral Energy Distributions in Galaxies
Burchat, Patricia R.; Meyers, Joshua E.; Kamath, Sowmya +1 more
Galaxy color gradients (CGs)—I.e., spectral energy distributions that vary across the galaxy profile—will impact galaxy shape measurements when the modeled point-spread function (PSF) corresponds to that for a galaxy with spatially uniform color. This paper describes the techniques and results of a study of the expected impact of galaxy CGs on wea…
Variability in Protoplanetary Nebulae: VII. Light-curve Studies of Five Medium-bright, Oxygen-rich, or Mixed-chemistry Post-AGB/Post-RGB Objects
Lu, Wenxian; Volk, Kevin; Hrivnak, Bruce J. +3 more
We have monitored over a 10-year interval the light variations of five evolved stars with very large mid-infrared excesses. All five objects appear to have oxygen-rich or mixed oxygen-rich and carbon-rich chemistries. They all vary in light: four over a small range of ∼0.2 mag and the fifth over a larger range of ∼0.7 mag. Spectral types range fro…
The Composite X-Ray Spectrum of 3CRR Quasars
Gu, Minfeng; Zhou, Minhua
The reason for the difference between the composite X-ray spectrum for radio-loud quasars (RLQs) versus radio-quiet quasars (RQQs) is still unclear. To study this difference, we built a new composite X-ray spectrum of RLQs using Chandra X-ray data and Sloan Digital Sky Survey optical data for the sample of 3CRR quasars. We find the X-ray spectra o…
Study of the Dynamics of Convective Turbulence in the Solar Granulation by Spectral Line Broadening and Asymmetry
Katsukawa, Yukio; Ishikawa, Ryohtaroh T.; Oba, Takayoshi +3 more
In quiet regions on the solar surface, turbulent convective motions of granulation play an important role in creating small-scale magnetic structures, as well as in energy injection into the upper atmosphere. The turbulent nature of granulation can be studied using spectral line profiles, especially line broadening, which contain information on th…
Flare Properties of A-type Stars in Kepler Data
Esamdin, Ali; Bai, Jian-Ying
We analyzed the long-cadence (LC) light curves of 5435 stars with effective temperatures of 7000-10,500 K in Data Release 25 of Kepler to extend the samples of A-type flare stars and study their flare properties. A total of 103 flare stars are detected, of which 72 have the Large Sky Area Multi-Object fiber Spectroscopic Telescope spectral types, …
Herschel SPIRE Discovery of Far-infrared Excess Synchrotron Emission from the West Hot Spot of the Radio Galaxy Pictor A
Isobe, Naoki; Pearson, Chris; Tashiro, Makoto +4 more
A far-infrared counterpart to the west hot spot of the radio galaxy Pictor A is discovered with the Spectral and Photometric Imaging REceiver (SPIRE) on board Herschel. The color-corrected flux density of the source is measured as 70.0 ± 9.9 mJy at the wavelength of 350 µm. A close investigation into its radio-to-optical spectrum indicates t…
Peak Temperatures of Large Solar X-Ray Flares and Associated CME Speeds and Widths
Kahler, S. W.; Ling, A. G.
We recently repeated an earlier analysis by Garcia showing that large (≥M3.0) solar X-ray flares associated with solar energetic particle (SEP) events have significantly lower peak X-ray flux ratios R = (0.04-0.5 nm)/(0.1-0.8 nm), proxies for flare peak temperatures, than those without SEP events. As we expect SEP events to be produced by shocks a…
A Mean Density of 112 M⊙ pc-3 for Central Molecular Zone Clumps—Evidences for Shear-enabled Pressure Equilibrium in the Galactic Center
Zhang, Chuan-Peng; Li, Guang-Xing
We carry out a systematic study of the density structure of gas in the Central Molecular Zone (CMZ) in the Galactic center by extracting clumps from the APEX Telescope Large Area Survey of the Galaxy survey at 870 µm. We find that the clumps follow a scaling of m = ρ0r3, which corresponds to a characteristic density of …