Search Publications
Variations between Dust and Gas in the Diffuse Interstellar Medium. III. Changes in Dust Properties
Heiles, Carl; Reach, William T.; Bernard, Jean-Philippe +1 more
We study infrared emission of 17 isolated, diffuse clouds with masses of order {10}2 {M}⊙ to test the hypothesis that grain property variations cause the apparently low gas-to-dust ratios that have been measured in those clouds. Maps of the clouds were constructed from Wide-field Infrared Survey Explorer (WISE) data and dire…
Shocks and Spatially Offset Active Galactic Nuclei Produce Velocity Offsets in Emission Lines
Greene, Jenny E.; Comerford, Julia M.; Barrows, R. Scott +1 more
While 2% of active galactic nuclei (AGNs) exhibit narrow emission lines with line-of-sight velocities that are significantly offset from the velocity of the host galaxy’s stars, the nature of these velocity offsets is unknown. We investigate this question with Chandra/ACIS and Hubble Space Telescope/Wide Field Camera 3 observations of seven veloci…
Spectral Variability of Two Rapidly Rotating Brown Dwarfs: 2MASS J08354256-0819237 and 2MASS J18212815+1414010
Schlawin, E.; Burgasser, Adam J.; Gizis, J. E. +2 more
L dwarfs exhibit low-level, rotationally modulated photometric variability generally associated with heterogeneous, cloud-covered atmospheres. The spectral character of these variations yields insight into the particle sizes and vertical structure of the clouds. Here, we present the results of a high-precision, ground-based, near-infrared, spectra…
A Suzaku View of Accretion-powered X-Ray Pulsar GX 1+4
Hoshino, Akio; Naik, Sachindra; Kitamoto, Shunji +3 more
We present results obtained from a Suzaku observation of the accretion-powered X-ray pulsar GX 1+4. A broadband continuum spectrum of the pulsar was found to be better described by a simple model consisting of a blackbody component and an exponential cutoff power law than the previously used compTT continuum model. Though the pulse profile had a s…
The Uncertainty of Local Background Magnetic Field Orientation in Anisotropic Plasma Turbulence
Saur, J.; Gerick, F.; von Papen, M.
In order to resolve and characterize anisotropy in turbulent plasma flows, a proper estimation of the background magnetic field is crucially important. Various approaches to calculating the background magnetic field, ranging from local to globally averaged fields, are commonly used in the analysis of turbulent data. We investigate how the uncertai…
The Formation of IRIS Diagnostics. IX. The Formation of the C I 135.58 NM Line in the Solar Atmosphere
Carlsson, Mats; Leenaarts, Jorrit; Lin, Hsiao-Hsuan
The C I 135.58 nm line is located in the wavelength range of NASA’s Interface Region Imaging Spectrograph (IRIS) small explorer mission. We study the formation and diagnostic potential of this line by means of non local-thermodynamic-equilibrium modeling, employing both 1D and 3D radiation-magnetohydrodynamic models. The C I/C II ionization balanc…
Detection of Prominent Stellar Disks in the Progenitors of Present-day Massive Elliptical Galaxies
Ho, Luis C.; Mobasher, Bahram; Canalizo, Gabriela +1 more
Massive galaxies at high redshifts (z > 2) show different characteristics from their local counterparts: they are compact and most likely have a disk. In this study, we trace the evolution of local massive galaxies by performing a detailed morphological analysis, namely, fitting single Sérsic profiles and performing bulge+disk decompositions. W…
CTIO, ROSAT HRI, and Chandra ACIS Observations of the Archetypical Mixed-morphology Supernova Remnant W28 (G6.4-0.1)
Kargaltsev, Oleg; Rho, Jeonghee; Hare, Jeremy +6 more
We present a joint analysis of optical emission-line and X-ray observations of the archetypical Galactic mixed-morphology supernova remnant (MMSNR) W28 (G6.4-0.1). MMSNRs comprise a class of sources whose shell-like radio morphology contrasts with a filled center in X-rays; the origin of these contrasting morphologies remains uncertain. Our CTIO i…
Multi-spacecraft Observations of the Coronal and Interplanetary Evolution of a Solar Eruption Associated with Two Active Regions
Wang, Rui; Yang, Zhongwei; Liu, Ying D. +3 more
We investigate the coronal and interplanetary evolution of a coronal mass ejection (CME) launched on 2010 September 4 from a source region linking two active regions (ARs), 11101 and 11103, using extreme ultraviolet imaging, magnetogram, white-light, and in situ observations from SDO, STEREO, SOHO, VEX, and Wind. A potential-field source-surface m…
Physical Properties of the Very Young PN Hen3-1357 (Stingray Nebula) Based on Multiwavelength Observations
Hubrig, S.; Otsuka, Masaaki; Parthasarathy, M. +1 more
We carried out a detailed analysis of the interesting and important very young planetary nebula (PN) Hen3-1357 (Stingray Nebula) based on a unique data set of optical to far-IR spectra and photometric images. We calculated the abundances of nine elements using collisionally excited lines (CELs) and recombination lines (RLs). The RL C/O ratio indic…