Search Publications
No Transition Disk? Infrared Excess, PAH, H2, and X-Rays from the Weak-Lined T Tauri Star DoAr 21
Cohen, David H.; Jensen, Eric L. N.; Gagné, Marc
As part of a program to understand disk dispersal and the interplay between circumstellar disks and X-ray emission, we present new high-resolution mid-infrared (IR) imaging, high-resolution optical spectroscopy, and Chandra grating X-ray spectroscopy of the weak-lined T Tauri star DoAr 21. DoAr 21 (age <106 yr and mass ~2.2 M su…
Analysis of narrowband emission observed in the Saturn magnetosphere
Gurnett, D. A.; Coates, A. J.; Santolik, O. +4 more
Narrowband emission is observed at Saturn centered near 5 kHz and 20 kHz and harmonics of 20 kHz. This emission appears to be in many ways similar to Jovian narrowband emission observed at higher frequencies. We analyze one example of this emission near a possible source region. In situ electron distributions suggest narrowband emission has a sour…
Simultaneous observations of flux transfer events by THEMIS, Cluster, Double Star, and SuperDARN: Acceleration of FTEs
Dandouras, I.; Fazakerley, A. N.; Milan, S. E. +3 more
We present simultaneous observations of flux transfer events (FTEs) made by the THEMIS and Cluster spacecraft on 3 May 2007, along with supporting observations of fast flows in the dayside ionosphere observed by the SuperDARN radar network. The THEMIS spacecraft were in a string-of-pearls formation approximately 20,000 km long and crossed the post…
The Highest Resolution Chandra View of Photoionization and Jet-Cloud Interaction in the Nuclear Region of NGC 4151
Zezas, A.; Elvis, M.; Fabbiano, G. +4 more
We report high resolution imaging of the nucleus of the Seyfert 1 galaxy NGC 4151 obtained with a 50 ks Chandra High Resolution Camera (HRC) observation. The HRC image resolves the emission on spatial scales of 0farcs5, ~30 pc, showing an extended X-ray morphology overall consistent with the narrow-line region (NLR) seen in optical line emission. …
Dynamic S0 Galaxies: A Case Study of NGC 5866
Wang, Q. Daniel; Li, Zhiyuan; Chen, Yang +1 more
S0 galaxies are often thought to be passively evolved from spirals after star formation is quenched. To explore what is actually occurring in such galaxies, we present a multi-wavelength case study of NGC 5866—a nearby edge-on S0 galaxy in a relatively isolated environment. This study shows strong evidence for dynamic activities in the interstella…
The Dusty Nebula Surrounding HR Car: A Spitzer View
Umana, G.; Fazio, G. G.; Hora, J. L. +3 more
We present mid-IR observations of the Galactic Luminous Blue Variable (LBV) HR Car and its associated nebula carried out with the Spitzer Space Telescope using both Infrared Array Camera and Infrared Spectrograph, as part of a GTO program aimed to study stellar ejecta from evolved stars. Our observations reveal a rich mid-IR spectrum of the inner …
Toward Reconstruction of Coronal Mass Ejection Density from Only Three Points of View
Morgan, H.; Frazin, R. A.; Manchester, W. B., IV +2 more
Understanding the structure of coronal mass ejections (CMEs) is one of the primary challenges in solar astrophysics. White-light coronagraphs make images of line-of-sight projections of the CME electron density (Ne ). The combination of the coronagraphs on the STEREO and SOHO spacecraft provides three simultaneous viewpoints that vary i…
INTEGRAL observation of hard X-ray variability of the TeV binary LS 5039/RX J1826.2-1450
Klochkov, D.; Santangelo, A.; Segreto, A. +4 more
Context: LS 5039 / RX J1826.2-1450 is one of the few High Mass X-ray binary systems from which radio and high energy TeV emission has been observed. Moreover, variability of the TeV emission with orbital period was detected.
Aims: We investigate the hard X-ray (25{-}200 keV) spectral and timing properties of the source with the monitoring IBIS…
The UV-Mid-IR Spectral Energy Distribution of a z = 1.7 Quasar Host Galaxy
Kochanek, C. S.; Assef, R. J.; Ross, N. R. +2 more
We have measured the spectral energy distribution (SED) of the host galaxy of the zs = 1.7 gravitationally lensed quasar SDSS J1004+4112 from 0.44-8.0 µm (0.16-3.0 µm in the rest frame). The large angular extent of the lensed images and their separation from the central galaxy of this cluster lens allows the images to be res…
Non-Maxwellian electron distributions in clusters of galaxies
Kaastra, J. S.; Werner, N.; Bykov, A. M.
Context: Thermal X-ray spectra of clusters of galaxies and other sources are commonly calculated assuming Maxwellian electron distributions. There are situations where this approximation is not valid, for instance near interfaces of hot and cold gas and near shocks.
Aims: The presence of non-thermal electrons affects the X-ray spectrum. To stu…