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A Survey of Far Ultraviolet Spectroscopic Explorer and Hubble Space Telescope Sight Lines through High-Velocity Cloud Complex C
Shull, J. Michael; Giroux, Mark L.; Collins, Joseph A.
Using archival Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope (HST) data, we have assembled a survey of eight sight lines through high-velocity cloud Complex C. Abundances of the observed ion species vary significantly for these sight lines, indicating that Complex C is not well characterized by a single metallicity. Reli…
A Relation between Supermassive Black Hole Mass and Quasar Metallicity?
Hamann, Fred; Dietrich, Matthias; Warner, Craig
We analyze spectra for a large sample of 578 active galactic nuclei to examine the relationships between broad emission line properties and central supermassive black hole (SMBH) mass. We estimate SMBH masses by applying the virial theorem to the C IV λ1549 broad emission line. Although the FWHMs of C IV and Hβ appear nearly unrelated in individua…
Production of gyrating ions from nonlinear wave-particle interaction upstream from the Earth's bow shock: A case study from Cluster-CIS
Lundin, R.; Balogh, A.; Dandouras, I. +14 more
We present observations of E<40 keV/e backstreaming ions measured by the Cluster Ion Spectrometry experiment at 1-2 RE upstream of the bow shock. The ions are simultaneously observed at all three spacecrafts for which CIS measurements are available. The proton distributions are analyzed using 4 s time resolution. They are observed in…
The Oort Constants Measured from Proper Motions
Olling, Rob P.; Dehnen, Walter
The Oort constants describe the local spatial variations of the stellar streaming field. The classic way for their determination employs their effect on stellar proper motions. We discuss various problems arising in this procedure. A large, hitherto apparently overlooked, source of potential systematic error arises from longitudinal variations of …
Density-Transition Scale at Quasiperpendicular Collisionless Shocks
Bale, S. D.; Horbury, T. S.; Mozer, F. S.
Measurements of a spacecraft floating potential, on the four Cluster spacecraft, are used as a proxy for electron plasma density to study, for the first time, the macroscopic density transition scale at 98crossings of the quasiperpendicular terrestrial bow shock. A timing analysis gives shock speeds and normals; the shock speed is used to convert …
Radial Velocity Studies of Close Binary Stars. VIII.
Rucinski, Slavek M.; Capobianco, Christopher C.; Lu, Wenxian +7 more
Radial velocity measurements and sine-curve fits to the orbital velocity variations are presented for the seventh set of 10 close binary systems: V410 Aur, V523 Cas, QW Gem, V921 Her, V2357 Oph, V1130 Tau, HN UMa, HX UMa, HD 93917, and NSV 223. All systems but three (V523 Cas, HD 93917, NSV 223) were discovered photometrically by the Hipparcos mis…
Heavy-element abundance patterns in hot DA white dwarfs
Barstow, M. A.; Bruhweiler, F. C.; Holberg, J. B. +5 more
We present a series of systematic abundance measurements for 25 hot DA white dwarfs in the temperature range ~20 000-110 000 K, based on far-ultraviolet spectroscopy with the Space Telescope Imaging Spectrograph (STIS)/Goddard High Resolution Spectrograph (GHRS) on-board Hubble Space Telescope, IUE and FUSE. Using our latest heavy-element blankete…
Nascent Starbursts in Synchrotron-deficient Galaxies with Hot Dust
Helou, G.; Roussel, H.; Beck, R. +4 more
Three nearby galaxies that have abnormally high infrared-to-radio continuum ratios, NGC 1377, IC 1953, and NGC 4491, are investigated with a view to understanding the physical origin of their peculiarity. We review the existing data and present new radio continuum measurements along with near-infrared integral-field spectroscopy and molecular gas …
VLBI astrometry of circumstellar OH masers: Proper motions and parallaxes of four AGB stars
Schilizzi, R. T.; Habing, H. J.; Vlemmings, W. H. T. +2 more
The main-line OH masers around 4 AGB stars have been observed with the NRAO Very Long Baseline Array (VLBA) at 8 epochs over a period of 2.5 yrs. Using a phase referencing technique, the position of the most compact maser spot of each star was monitored with respect to two extragalactic reference sources. For U Her and W Hya, we observe the most b…
The radiative response of solar loop plasma subject to transient heating
Mason, H. E.; Bradshaw, S. J.
In Bradshaw & Mason (\cite{Bradshaw2003}) we carried out a hydrodynamic simulation of a cooling solar loop and investigated the nonequilibrium response of the population of C VII ions to the changing conditions in the plasma. We also compared equilibrium and nonequilibrium calculations of the total plasma emissivity. In this paper we present t…