Search Publications
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…
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…