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Hubble Space Telescope Observations of Element Abundances in Low-Redshift Damped Lyα Galaxies and Implications for the Global Metallicity-Redshift Relation
York, Donald G.; Fall, S. Michael; Kulkarni, Varsha P. +4 more
Most models of cosmic chemical evolution predict that the mass-weighted mean interstellar metallicity of galaxies should rise with time from a low value ~1/30 solar at z~3 to a nearly solar value at z=0. In the absence of any selection effects, the damped Lyα absorbers (DLAs) in quasar spectra are expected to show such a rise in global metallicity…
The Low-z Intergalactic Medium. I. O VI Baryon Census
Shull, J. Michael; Danforth, Charles W.
Intergalactic absorbers along lines of sight to distant quasars are a powerful diagnostic for the evolution and content of the intergalactic medium (IGM). In this study, we use the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite to search 129 known Lyα absorption systems at z<0.15 toward 31 active galactic nuclei (AGNs) for correspondin…
The vertical profile of winds on Titan
Plettemeier, D.; Gurvits, L. I.; Pogrebenko, S. V. +12 more
One of Titan's most intriguing attributes is its copious but featureless atmosphere. The Voyager 1 fly-by and occultation in 1980 provided the first radial survey of Titan's atmospheric pressure and temperature and evidence for the presence of strong zonal winds. It was realized that the motion of an atmospheric probe could be used to study the wi…
Coronal Evolution of the Sun in Time: High-Resolution X-Ray Spectroscopy of Solar Analogs with Different Ages
Skinner, Stephen L.; Güdel, Manuel; Ness, Jan-Uwe +3 more
We investigate the long-term evolution of X-ray coronae of solar analogs based on high-resolution X-ray spectroscopy and photometry with XMM-Newton. Six nearby main-sequence G stars with ages between ~0.1 and ~1.6 Gyr and rotation periods between ~1 and 12.4 days have been observed. We use the X-ray spectra to derive coronal element abundances of …
VLT spectroscopy of globular cluster systems. II. Spectroscopic ages, metallicities, and [ α/Fe] ratios of globular clusters in early-type galaxies
Saglia, R. P.; Thomas, D.; Bender, R. +5 more
An analysis of ages, metallicities, and [ α/Fe] ratios of globular cluster systems in early-type galaxies is presented, based on Lick index measurements summarized in Puzia et al. (2004, A&A, 415, 123, Paper I of this series). In the light of calibration and measurement uncertainties, age-metallicity degeneracy, and the relative dynamic range …
Reconnection in a rotation-dominated magnetosphere and its relation to Saturn's auroral dynamics
Jackman, C. M.; Milan, S. E.; Yeoman, T. K. +6 more
The first extended series of observations of Saturn's auroral emissions, undertaken by the Hubble Space Telescope in January 2004 in conjunction with measurements of the upstream solar wind and interplanetary magnetic field (IMF) by the Cassini spacecraft, have revealed a strong auroral response to the interplanetary medium. Following the arrival …
Dynamics of Saturn's Magnetosphere from MIMI During Cassini's Orbital Insertion
Livi, S.; Hsieh, K. C.; Krupp, N. +29 more
The Magnetospheric Imaging Instrument (MIMI) onboard the Cassini spacecraft observed the saturnian magnetosphere from January 2004 until Saturn orbit insertion (SOI) on 1 July 2004. The MIMI sensors observed frequent energetic particle activity in interplanetary space for several months before SOI. When the imaging sensor was switched to its energ…
Evolution of the Near-Infrared Tully-Fisher Relation: Constraints on the Relationship between the Stellar and Total Masses of Disk Galaxies since z~1
Conselice, Christopher J.; Ellis, Richard S.; Bundy, Kevin +3 more
Using a combination of Keck spectroscopy and near-infrared imaging, we investigate the K-band and stellar-mass Tully-Fisher relation for 101 disk galaxies at 0.2<z<1.2, with the goal of placing the first observational constraints on the assembly history of halo and stellar mass. Our main result is a lack of evolution in either the K-band or …
From Radio to X-Ray: Flares on the dMe Flare Star EV Lacertae
Hawley, Suzanne L.; Johns-Krull, Christopher M.; Osten, Rachel A. +2 more
We present the results of a campaign to observe flares on the M dwarf flare star EV Lacertae over the course of two days in 2001 September, utilizing a combination of radio continuum, optical photometric and spectroscopic, ultraviolet spectroscopic, and X-ray spectroscopic observations to characterize the multiwavelength nature of flares from this…
The CME-flare relationship: Are there really two types of CMEs?
Vršnak, B.; Sudar, D.; Ruždjak, D.
We present a statistical analysis of 545 flare-associated CMEs and 104 non-flare CMEs observed in the heliocentric distance range 2-30 solar radii. We found that both data sets show quite similar characteristics, contradicting the concept of two distinct (flare/non-flare) types of CMEs. In both samples there is a significant fraction of CMEs showi…