Search Publications
A fracture history on Enceladus provides evidence for a global ocean
Patthoff, D. Alex; Kattenhorn, Simon A.
The region surrounding the south pole of Saturn's moon Enceladus shows a young, pervasively fractured surface that emanates enough heat to be detected by the Cassini spacecraft. To explain the elevated heat and eruptive icy plumes originating from large cracks (informally called “tiger stripes”) in the surface, many models implicitly assume a glob…
The Sun's Small-scale Magnetic Elements in Solar Cycle 23
Zhao, H.; Wang, J. X.; Jin, C. L. +1 more
With the unique database from the Michelson Doppler Imager on board the Solar and Heliospheric Observatory in an interval embodying solar cycle 23, the cyclic behavior of solar small-scale magnetic elements is studied. More than 13 million small-scale magnetic elements are selected, and the following results are found. (1) The quiet regions domina…
Star Formation Efficiency in the Cool Cores of Galaxy Clusters
Veilleux, Sylvain; Rupke, David S. N.; Mushotzky, Richard +2 more
We have assembled a sample of high spatial resolution far-UV (Hubble Space Telescope Advanced Camera for Surveys/Solar Blind Channel) and Hα (Maryland-Magellan Tunable Filter) imaging for 15 cool core galaxy clusters. These data provide a detailed view of the thin, extended filaments in the cores of these clusters. Based on the ratio of the far-UV…
Discovery of close binary central stars in the planetary nebulae NGC 6326 and NGC 6778
Corradi, R. L. M.; Santander-García, M.; Boffin, H. M. J. +3 more
We present observations proving the close binary nature of the central stars belonging to the planetary nebulae (PNe) NGC 6326 and NGC 6778. Photometric monitoring reveals irradiated lightcurves with orbital periods of 0.372 and 0.1534 days, respectively, constituting firm evidence that they passed through a common-envelope (CE) phase. Unlike most…
Geophysical implications of the long-wavelength topography of the Saturnian satellites
Nimmo, F.; Thomas, P. C.; Bills, B. G.
We use limb profiles to quantify the long-wavelength topography of the Saturnian satellites. The degree 2 shapes of Mimas, Enceladus, and Tethys are not consistent with hydrostatic equilibrium. We derive 2-D topographic maps out to spherical harmonic degree 8. There is a good correlation with topography derived from stereo techniques. If uncompens…
Imaging the Molecular Gas Properties of a Major Merger Driving the Evolution of a z = 2.5 Submillimeter Galaxy
Walter, Fabian; Hodge, Jacqueline; Riechers, Dominik A. +6 more
We report the detection of spatially extended CO(J = 1→0) and CO(J = 5→4) emission in the z = 2.49 submillimeter galaxy (SMG) J123707+6214, using the Expanded Very Large Array and the Plateau de Bure Interferometer. The large molecular gas reservoir is spatially resolved into two CO(J = 1→0) components (northeast and southwest; previously identifi…
A Census of Baryons and Dark Matter in an Isolated, Milky Way Sized Elliptical Galaxy
Fabian, Andrew C.; Canizares, Claude R.; Humphrey, Philip J. +2 more
We present a study of the dark and luminous matter in the isolated elliptical galaxy NGC 720, based on deep X-ray observations made with the Chandra and Suzaku observatories. The gas properties are reliably measured almost to R 2500, allowing us to place good constraints on the enclosed mass and baryon fraction (fb ) within t…
Geometry and inclination of the broad-line region in blazars
Treves, A.; Decarli, R.; Dotti, M.
We study the properties of the broad-line region in blazars by comparing the virial estimate of black hole masses with that derived from the mass of the host galaxies. The former is sensitive to the width of broad lines, i.e. to the projection of the velocity of line-emitting clouds along the line of sight; the latter is not. This comparison allow…
The Massive Progenitor of the Possible Type II-Linear Supernova 2009hd in Messier 66
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Foley, Ryan J. +11 more
We present early- and late-time photometric and spectroscopic observations of supernova (SN) 2009hd in the nearby spiral galaxy NGC 3627 (M66). This SN is one of the closest to us in recent years and provides an uncommon opportunity to observe and study the nature of SNe. However, the object was heavily obscured by dust, rendering it unusually fai…
Feeding and feedback in the active nucleus of Mrk 1157 probed with the Gemini Near-Infrared Integral-Field Spectrograph
Storchi-Bergmann, Thaisa; Riffel, Rogemar A.
We have mapped the stellar and gaseous kinematics, as well as the emission-line flux distributions and ratios, from the inner ≈450 pc radius of the Seyfert 2 galaxy Mrk 1157, using two-dimensional near-infrared J- and Kl-band spectra obtained with the Gemini Near-Infrared Integral-Field Spectrograph instrument at a spatial resolution of…