Search Publications
Nonlinear Force-free Field Modeling of a Solar Active Region around the Time of a Major Flare and Coronal Mass Ejection
Aulanier, G.; Schrijver, C. J.; Amari, T. +14 more
Solar flares and coronal mass ejections are associated with rapid changes in field connectivity and are powered by the partial dissipation of electrical currents in the solar atmosphere. A critical unanswered question is whether the currents involved are induced by the motion of preexisting atmospheric magnetic flux subject to surface plasma flows…
An Infrared Survey of Brightest Cluster Galaxies. II. Why are Some Brightest Cluster Galaxies Forming Stars?
Baum, Stefi A.; O'Dea, Christopher P.; Sarazin, Craig L. +12 more
Quillen et al. presented an imaging survey with the Spitzer Space Telescope of 62 brightest cluster galaxies with optical line emission located in the cores of X-ray-luminous clusters. They found that at least half of these sources have signs of excess IR emission. Here we discuss the nature of the IR emission and its implications for cool core cl…
Unveiling Obscured Accretion in the Chandra Deep Field-South
Pozzi, F.; Fiore, F.; Vignali, C. +10 more
We make use of deep HST, VLT, Spitzer, and Chandra data on the Chandra Deep Field-South to constrain the number of Compton-thick AGNs in this field. We show that sources with high 24 µm-to-optical flux ratios and red colors form a distinct source population, and that their infrared luminosity is dominated by AGN emission. Analysis of the X-r…
Hinode SOT Observations of Solar Quiescent Prominence Dynamics
Tsuneta, Saku; Shimizu, Toshifumi; Okamoto, Takenori J. +9 more
We report findings from multihour 0.2'' resolution movies of solar quiescent prominences (QPs) observed with the Solar Optical Telescope (SOT) on the Hinode satellite. The observations verify previous findings of filamentary downflows and vortices in QPs. SOT observations also verify large-scale transverse oscillations in QPs, with periods of 20-4…
Recent Structural Evolution of Early-Type Galaxies: Size Growth from z = 1 to z = 0
Franx, Marijn; Illingworth, Garth D.; van der Wel, Arjen +4 more
Strong size and internal density evolution of early-type galaxies between z ~ 2 and the present has been reported by several authors. Here we analyze samples of nearby and distant (z ~ 1) galaxies with dynamically measured masses in order to confirm the previous, model-dependent results and constrain the uncertainties that may play a role. Velocit…
Small-Scale Energy Cascade of the Solar Wind Turbulence
Alexandrova, O.; Carbone, V.; Veltri, P. +1 more
Magnetic fluctuations in the solar wind are distributed according to Kolmogorov's power law f-5/3 below the ion cyclotron frequency fci. Above this frequency, the observed steeper power law is usually interpreted in two different ways, as a dissipative range of the solar wind turbulence, or another turbulent cascade, the natu…
Theoretical Spectra and Light Curves of Close-in Extrasolar Giant Planets and Comparison with Data
Burrows, A.; Budaj, J.; Hubeny, I.
We present theoretical atmosphere, spectral, and light-curve models for extrasolar giant planets (EGPs) undergoing strong irradiation for which Spitzer planet/star contrast ratios or light curves have been published (circa 2007 June). These include HD 209458b, HD 189733b, TrES-1, HD 149026b, HD 179949b, and υ And b. By comparing models with data, …
Variations of the Mid-IR Aromatic Features inside and among Galaxies
Madden, Suzanne C.; Jones, Anthony P.; Galliano, Frédéric +2 more
We present the results of a systematic study of mid-IR spectra of Galactic regions, Magellanic H II regions, and galaxies of various types (dwarf, spiral, starburst), observed by the satellites ISO and Spitzer. We study the relative variations of the 6.2, 7.7, 8.6, and 11.3 µm features inside spatially resolved objects (such as M82, M51, 30 …
Evidence for Quasar Activity Triggered by Galaxy Mergers in HST Observations of Dust-reddened Quasars
Lacy, Mark; Becker, Robert H.; Urrutia, Tanya
We present Hubble Space Telescope ACS images of 13 dust-reddened type 1 quasars selected from the FIRST/2MASS Red Quasar Survey. These quasars have high intrinsic luminosities after correction for dust obscuration (-23.5 >= MB >= - 26.2 from K-magnitude). The images show strong evidence of recent or ongoing interaction in 11 of th…
Ultraviolet Survey of CO and H2 in Diffuse Molecular Clouds: The Reflection of Two Photochemistry Regimes in Abundance Relationships
Abel, N. P.; Gredel, R.; Lambert, D. L. +4 more
We carried out a comprehensive far-UV survey of 12CO and H2 column densities along diffuse molecular Galactic sight lines. This sample includes new measurements of CO from HST spectra along 62 sight lines and new measurements of H2 from FUSE data along 58 sight lines. In addition, high-resolution optical data were …