Search Publications
Herschel Measurements of Molecular Oxygen in Orion
Caselli, Paola; Li, Di; Viti, Serena +32 more
We report observations of three rotational transitions of molecular oxygen (O2) in emission from the H2 Peak 1 position of vibrationally excited molecular hydrogen in Orion. We observed the 487 GHz, 774 GHz, and 1121 GHz lines using the Heterodyne Instrument for the Far Infrared on the Herschel Space Observatory, having veloc…
Secular Evolution and a Non-evolving Black-hole-to-galaxy Mass Ratio in the Last 7 Gyr
Koekemoer, Anton M.; Trump, Jonathan R.; Jahnke, Knud +6 more
We present new constraints on the ratio of black hole (BH) mass to total galaxy stellar mass at 0.3 < z < 0.9 for a sample of 32 type-1 active galactic nuclei (AGNs) from the XMM-COSMOS survey covering the range M BH ~ 107.2 - 8.7 M sun. Virial M BH estimates based on Hβ are available from the COSM…
Numerical Investigation of a Coronal Mass Ejection from an Anemone Active Region: Reconnection and Deflection of the 2005 August 22 Eruption
Gombosi, T. I.; Shibata, K.; Lugaz, N. +3 more
We present a numerical investigation of the coronal evolution of a coronal mass ejection (CME) on 2005 August 22 using a three-dimensional thermodynamic magnetohydrodynamic model, the space weather modeling framework. The source region of the eruption was anemone active region (AR) 10798, which emerged inside a coronal hole. We validate our modele…
Using a Differential Emission Measure and Density Measurements in an Active Region Core to Test a Steady Heating Model
Winebarger, Amy R.; Warren, Harry P.; Kashyap, Vinay L. +2 more
The frequency of heating events in the corona is an important constraint on the coronal heating mechanisms. Observations indicate that the intensities and velocities measured in active region cores are effectively steady, suggesting that heating events occur rapidly enough to keep high-temperature active region loops close to equilibrium. In this …
Connection Between the Accretion Disk and Jet in the Radio Galaxy 3C 111
Rothschild, Richard E.; McHardy, Ian M.; Rivers, Elizabeth +13 more
We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 111 between 2004 and 2010 at X-ray (2.4-10 keV), optical (R band), and radio (14.5, 37, and 230 GHz) wave bands, as well as multi-epoch imaging with the Very Long Baseline Array (VLBA) at 43 GHz. Over the six years of observation, significant dips in the X-ray li…
Influence of the Ambient Solar Wind Flow on the Propagation Behavior of Interplanetary Coronal Mass Ejections
Veronig, Astrid M.; Temmer, Manuela; Vršnak, Bojan +3 more
We study three coronal mass ejection (CME)/interplanetary coronal mass ejection (ICME) events (2008 June 1-6, 2009 February 13-18, and 2010 April 3-5) tracked from Sun to 1 AU in remote-sensing observations of Solar Terrestrial Relations Observatory Heliospheric Imagers and in situ plasma and magnetic field measurements. We focus on the ICME propa…
Scaling Relations and Overabundance of Massive Clusters at z >~ 1 from Weak-lensing Studies with the Hubble Space Telescope
Gladders, M. D.; Ford, H. C.; Huang, X. +22 more
We present weak gravitational lensing analysis of 22 high-redshift (z >~ 1) clusters based on Hubble Space Telescope images. Most clusters in our sample provide significant lensing signals and are well detected in their reconstructed two-dimensional mass maps. Combining the current results and our previous weak-lensing studies of five other hig…
Rocky Extrasolar Planetary Compositions Derived from Externally Polluted White Dwarfs
Koester, D.; Zuckerman, B.; Klein, B. +1 more
We report Keck High Resolution Echelle Spectrometer data and model atmosphere analysis of two helium-dominated white dwarfs, PG1225-079 and HS2253+8023, whose heavy pollutions most likely derive from the accretion of terrestrial-type planet(esimal)s. For each system, the minimum accreted mass is ~1022 g, that of a large asteroid. In PG1…
Solar Wind Modeling with Turbulence Transport and Heating
Matthaeus, William H.; Goldstein, Melvyn L.; Usmanov, Arcadi V. +1 more
We have developed an axisymmetric steady-state solar wind model that describes properties of the large-scale solar wind, interplanetary magnetic field, and turbulence throughout the heliosphere from 0.3 AU to 100 AU. The model is based on numerical solutions of large-scale Reynolds-averaged magnetohydrodynamic equations coupled with a set of small…
Morphology and Size Differences Between Local and High-redshift Luminous Infrared Galaxies
Juneau, Stéphanie; Rieke, George H.; Eisenstein, Daniel J. +1 more
We show that the star-forming regions in high-redshift luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) and submillimeter galaxies (SMGs) have similar physical scales to those in local normal star-forming galaxies. To first order, their higher infrared (IR) luminosities result from higher luminosity surface density. We also find a g…