Search Publications
Nonthermal X-ray Emission in the N11 Superbubble in the Large Magellanic Cloud
Chu, Y. -H.; Williams, R. M.; Maddox, L. A. +1 more
We present the results of X-ray spectral analysis of the superbubble (SB) around the OB association LH9 in the H II complex N11 in the Large Magellanic Cloud. Using observations from Suzaku, we have modeled the X-ray emission over the energy range 0.2-7.5 keV. We constrained the thermal spectrum below 2 keV using a thermal plasma model found in a …
Direct Observation of a Corotating Interaction Region by Three Spacecraft
Tappin, S. J.; Howard, T. A.
White-light observations of interplanetary disturbances have been dominated by interplanetary coronal mass ejections (ICMEs). This is because the other type of disturbance, the corotating interaction region (CIR), has proved difficult to detect using white-light imagers. Recently, a number of papers have appeared presenting CIR observations using …
Formation Conditions of Enceladus and Origin of Its Methane Reservoir
Lunine, J. I.; Waite, J. H.; Magee, B. +5 more
We describe a formation scenario of Enceladus constrained by the deuterium-to-hydrogen ratio (D/H) in the gas plumes as measured by the Cassini Ion and Neutral Mass Spectrometer. We propose that, similarly to Titan, Enceladus formed from icy planetesimals that were partly devolatilized during their migration within the Kronian subnebula. In our sc…
Cosmic Origins Spectrograph Observations of the Chemical Composition of SNR LMC N132D
Shull, J. Michael; Danforth, Charles W.; France, Kevin +4 more
We present new far-ultraviolet (far-UV) spectra of an oxygen-rich knot in the Large Magellanic Cloud supernova remnant N132D, obtained with the Hubble Space Telescope (HST)-Cosmic Origins Spectrograph (COS). Moderate-resolution (Δv ≈ 200 km s-1) spectra in the HST far-UV bandpass (1150 Å lsim λ lsim 1750 Å) show emission from several io…
The Nuclear Outflows and Feedback in the Seyfert 2 Galaxy Markarian 573
Shields, Joseph C.; Pogge, Richard W.; Martini, Paul +2 more
We present a study of outflow and feedback in the well known Seyfert 2 galaxy Markarian 573 using high-angular resolution long-slit spectrophotometry obtained with the Hubble Space Telescope Imaging Spectrograph (STIS). Through analysis of the kinematics and ionization state of a biconical outflow region emanating from the nucleus, we find that th…
X-ray Emission from the FU Orionis Star V1735 Cygni
Skinner, Stephen L.; Güdel, Manuel; Sokal, Kimberly R. +1 more
The variable star V1735 Cyg (=Elias 1-12) lies in the IC 5146 dark cloud and is a member of the class of FU Orionis objects whose dramatic optical brightenings are thought to be linked to episodic accretion. We report the first X-ray detections of V1735 Cyg and a deeply embedded class I protostar lying 24'' to its northeast. X-ray spectra obtained…
Absorption of p Modes by Thin Magnetic Flux Tubes
Birch, Aaron C.; Jain, Rekha; Hindman, Bradley W. +1 more
We study the interaction between p modes and the many magnetic fibrils that lace the solar convection zone. In particular, we investigate the resulting absorption of p-mode energy by the fibril magnetic field. Through mechanical buffeting, the p modes excite tube waves on the magnetic fibrils—in the form of longitudinal sausage waves and transvers…
A Suzaku Observation of NGC 4593: Illuminating the Truncated Disk
Reeves, J. N.; Markowitz, A. G.
We report results from a 2007 Suzaku observation of the Seyfert 1 AGN NGC 4593. The narrow Fe Kα emission line has a FWHM width ~ 4000 km s-1, indicating emission from gsim 5000 R g. There is no evidence for a relativistically broadened Fe K line, consistent with the presence of a radiatively efficient outer disk which is tru…
Measurements of Absorption, Emissivity Reduction, and Local Suppression of Solar Acoustic Waves in Sunspots
Zhao, Hui; Liang, Zhi-Chao; Chou, Dean-Yi +2 more
The power of solar acoustic waves in magnetic regions is lower relative to the quiet Sun. Absorption, emissivity reduction, and local suppression of acoustic waves contribute to the observed power reduction in magnetic regions. We propose a model for the energy budget of acoustic waves propagating through a sunspot in terms of the coefficients of …
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…