Search Publications
Magnetic Field-line Lengths in Interplanetary Coronal Mass Ejections Inferred from Energetic Electron Events
Richardson, I. G.; Kahler, S. W.; Haggerty, D. K.
About one quarter of the observed interplanetary coronal mass ejections (ICMEs) are characterized by enhanced magnetic fields that smoothly rotate in direction over timescales of about 10-50 hr. These ICMEs have the appearance of magnetic flux ropes and are known as "magnetic clouds" (MCs). The total lengths of MC field lines can be determined usi…
Molecular Environment and an X-Ray Spectroscopy of Supernova Remnant Kesteven 78
Zhou, Ping; Chen, Yang
We investigate the molecular environment of the Galactic supernova remnant (SNR) Kesteven 78 and perform an XMM-Newton X-ray spectroscopic study for the northeastern edge of the remnant. SNR Kes 78 is found to interact with the molecular clouds (MCs) at a systemic local standard of rest velocity of 81 km s-1. At around this velocity, th…
The Far-ultraviolet "Continuum" in Protoplanetary Disk Systems. I. Electron-impact H2 and Accretion Shocks
France, Kevin; Yang, Hao; Linsky, Jeffrey L.
We present deep spectroscopic observations of the classical T Tauri stars DF Tau and V4046 Sgr in order to better characterize two important sources of far-ultraviolet continuum emission in protoplanetary disks. These new Hubble Space Telescope-Cosmic Origins Spectrograph observations reveal a combination of line and continuum emission from collis…
The Acoustic Cutoff Frequency of the Sun and the Solar Magnetic Activity Cycle
García, R. A.; Pallé, P. L.; Jiménez, A.
The acoustic cutoff frequency—the highest frequency for acoustic solar eigenmodes—is an important parameter of the solar atmosphere as it determines the upper boundary of the p-mode resonant cavities. At frequencies beyond this value, acoustic disturbances are no longer trapped but are traveling waves. Interference among them gives rise to higher-…
Chandra Observation of the TeV Source HESS J1834-087
Pavlov, George G.; Kargaltsev, Oleg; Misanovic, Zdenka
Chandra ACIS observed the field of the extended TeV source HESS J1834-087 for 47 ks. A previous XMM-Newton EPIC observation of the same field revealed a point-like source (XMMU J183435.3-084443) and an offset region of faint extended emission. In the low-resolution, binned EPIC images the two appear to be connected. However, the high-resolution Ch…
Case Study of Four Homologous Large-scale Coronal Waves Observed on 2010 April 28 and 29
Temmer, M.; Nitta, N.; Veronig, A. M. +3 more
On 2010 April 28 and 29, the Solar TErrestrial Relations Observatory B/Extreme Ultraviolet Imager observed four homologous large-scale coronal waves, the so-called EIT-waves, within 8 hr. All waves emerged from the same source active region, were accompanied by weak flares and faint coronal mass ejections, and propagated into the same direction at…
Suzaku View of the Swift/BAT Active Galactic Nuclei. III. Application of Numerical Torus Models to Two Nearly Compton Thick Active Galactic Nuclei (NGC 612 and NGC 3081)
Aird, James; Ueda, Yoshihiro; Awaki, Hisamitsu +3 more
The broadband spectra of two Swift/BAT active galactic nuclei (AGNs) obtained from Suzaku follow-up observations are studied: NGC 612 and NGC 3081. Fitting with standard models, we find that both sources show similar spectra characterized by heavy absorption with N H ~= 1024 cm-2, and the fraction of scattered ligh…
Precise Estimates of the Physical Parameters for the Exoplanet System HD 17156 Enabled by Hubble Space Telescope Fine Guidance Sensor Transit and Asteroseismic Observations
Nelan, Edmund P.; Gilliland, Ronald L.; Christensen-Dalsgaard, Jørgen +6 more
We present observations of three distinct transits of HD 17156b obtained with the Fine Guidance Sensors on board the Hubble Space Telescope. We analyzed both the transit photometry and previously published radial velocities to find the planet-star radius ratio Rp /R sstarf = 0.07454 ± 0.00035, inclination i = 86.49+0.24<…
Molecular Gas Evolution Across a Spiral Arm in M51
Scoville, Nick; Koda, Jin; Egusa, Fumi
We present sensitive and high angular resolution CO(1-0) data obtained by the Combined Array for Research in Millimeter-wave Astronomy observations toward the nearby grand-design spiral galaxy M51. The angular resolution of 0farcs7 corresponds to 30 pc, which is similar to the typical size of giant molecular clouds (GMCs), and the sensitivity is a…
The Infrared Continuum Sizes of Be Star Disks
Gies, D. R.; Schaefer, G. H.; Touhami, Y.
We present an analysis of the near-infrared continuum emission from the circumstellar gas disks of Be stars using a radiative transfer code for a parameterized version of the viscous decretion disk model. This isothermal gas model creates predicted images that we use to estimate the half-width at half-maximum emission radius along the major axis o…