321 citations · 6.3k across the 122 of their papers we have counts for
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The Connection between a Lyman Limit System, a very strong OVI Absorber, and Galaxies at z~0.203
N. Lehner, J. X. Prochaska, H. A. Kobulnicky +4
With a column density log N(OVI) = 14.95+/-0.05, the OVI absorber at z_abs~0.2028 observed toward the QSO PKS0312-77 (z_em=0.223) is the strongest yet detected at z<0.5. At nearly…
Probing feedback in protogalaxies: Multiphase gas in a DLA at z~2.4
N. Lehner, J. C. Howk, J. X. Prochaska +1
We investigate the physical processes occuring in the multiphase gas of a damped Lyαsystem (DLA). We base our analysis on a high quality Keck HIRES spectrum of the QSO J1211+0422 i…
The High Velocity Gas toward Messier 5: Tracing Feedback Flows in the Inner Galaxy
William F. Zech, Nicolas Lehner, J. Christopher Howk +2
We present Far Ultraviolet Spectroscopic Explorer (FUSE) and Space Telescope Imaging Spectrograph (STIS E140M) observations of the post-asymptotic giant branch star ZNG 1 in the gl…
Metallicity and Physical Conditions in the Magellanic Bridge
N. Lehner, J. C. Howk, F. P. Keenan +1
We present a new analysis of the diffuse gas in the Magellanic Bridge (RA>3h) based on HST/STIS E140M and FUSE spectra of 2 early-type stars lying within the Bridge and a QSO behin…
Simulating Anisotropic Thermal Conduction in Supernova Remnants, Implications for the Interstellar Medium
D. S. Balsara, A. J. Bendinelli, D. A. Tilley +2
We present a large number of two and a half dimensional simulations of supernova remnants expanding into interstellar media having a range of densities, temperatures and magnetic f…
Distances to Galactic high-velocity clouds. Complex C
B. P. Wakker, D. G. York, J. C. Howk +8
We report the first determination of a distance bracket for the high-velocity cloud (HVC) complex C. Combined with previous measurements showing that this cloud has a metallicity o…
Distances to Galactic high-velocity clouds. I. Cohen Stream, complex GCP, cloud g1
B. P. Wakker, D. G. York, R. Wilhelm +5
The high- and intermediate-velocity interstellar clouds (HVCs/IVCs) are tracers of energetic processes in and around the Milky Way. Clouds with near-solar metallicity about one kpc…
Highly ionised plasma in the Large Magellanic Cloud: Evidence for outflows and a possible galactic wind
N. Lehner, J. C. Howk
Based on an analysis of the interstellar highly ionised species C IV, Si IV, N V, and O VI observed in the FUSE and HST/STIS E140M spectra of four hot stars in the Large Magellanic…
The Ucsd/Keck Damped Lya Abundance Database: A Decade of High Resolution Spectroscopy
Jason X. Prochaska, Arthur M. Wolfe, J. Christopher Howk +3
We publish the Keck/HIRES and Keck/ESI spectra that we have obtained during the first 10 years of Keck observatory operations. Our full sample includes 42 HIRES spectra and 39 ESI…
Strongly Variable z=1.48 FeII and MgII Absorption in the Spectra of z=4.05 GRB 060206
H. Hao, K. Z. Stanek, A. Dobrzycki +9
We report on the discovery of strongly variable FeII and MgII absorption lines seen at z=1.48 in the spectra of the z=4.05 GRB 060206 obtained between 4.13 to 7.63 hours (observer…
Simulating Anisotropic Thermal Conduction in Supernova Remnants I : Numerics and the Evolution of Remnants
D. S. Balsara, D. A. Tilley, J. C. Howk
Anisotropic thermal conduction plays an important role in various astrophysical systems. One of the most stringent tests of thermal conduction can be found in supernova remnants. I…
Simulations of Mixed Morphology Supernova Remnants With Anisotropic Thermal Conduction
David A. Tilley, Dinshaw S. Balsara, J. Christopher Howk
We explore the role of anisotropic thermal conduction on the evolution of supernova remnants through interstellar media with a range of densities via numerical simulations. We find…
The UCSD Radio-Selected Quasar Survey for Damped Lyman alpha System
Regina A. Jorgenson, Arthur M. Wolfe, Jason X. Prochaska +5
As large optical quasar surveys for damped Lya become a reality and the study of star forming gas in the early Universe achieves statistical robustness, it is now vital to identify…
Evidence for Correlated Titanium and Deuterium Depletion in the Galactic ISM
Jason X. Prochaska, Todd M. Tripp, J. Christopher Howk
Current measurements indicate that the deuterium abundance in diffuse interstellar gas varies spatially by a factor of ~4 among sightlines extending beyond the Local Bubble. One pl…
Extraplanar Dust: a Tracer of Cold Dense Gas in the Thick Disks of Spiral Galaxies
J. Christopher Howk
The interstellar thick disks of galaxies contain not only gas, but significant quantities of dust. Most of our knowledge of extraplanar dust in disk galaxies comes from direct broa…
Elemental Abundances in Two High Column Density Damped Lyman Alpha Systems at z < 1.5
Sandhya M. Rao, Jason X. Prochaska, J. Christopher Howk +1
We present Keck/HIRES abundance measurements and metal-line kinematic profiles of the damped Lyman alpha systems (DLAs) towards the quasars Q0933+733 (z_abs=1.479) and Q0948+433 (z…
Small-Scale Structure of O VI Interstellar Gas in the Direction of the Globular Cluster NGC 6752
N. Lehner, J. C. Howk
In order to study the small-scale structure of the hot interstellar gas, we obtained Far Ultraviolet Spectroscopic Explorer interstellar O VI interstellar absorption spectra of 4 f…
Probing the IGM/Galaxy Connection Toward PKS0405-123 I: UV Spectroscopy and Metal-Line Systems
Jason X. Prochaska, Hsiao-Wen Chen, J. Christopher Howk +2
We present results from an analysis of FUSE and HST/STIS spectroscopy of the z_em=0.57 quasar PKS0405-123. We focus on the intervening metal-line systems identified along the sight…
Cold Neutral Gas in a z=4.2 Damped Lyman-alpha System: The Fuel for Star Formation
J. Christopher Howk, Arthur M. Wolfe, Jason X. Prochaska
We discuss interstellar temperature determinations using the excitation equilibrium of the ^2P levels of Si II and C II. We show how observations of the ^2P_3/2 fine structure leve…
Cooling in Coronal Gas in the M82 Starburst Superwind
Charles G. Hoopes, Timothy M. Heckman, David K. Strickland +1
We have used the Far Ultraviolet Spectroscopic Explorer to search for OVI 1031.926 Angstrom emission at four locations in the starburst superwind of M82. No OVI emission was detect…
H_2 absorption in a dense interstellar filament in the Milky Way halo
P. Richter, K. R. Sembach, J. C. Howk
We investigate interstellar absorption from molecular hydrogen (H_2) and metals in an intermediate-velocity cloud (IVC) in the direction of the LMC star Sk -68 80 (HD 36521), based…
The elemental abundance pattern in a galaxy at z=2.626
Jason X. Prochaska, J. Chris Howk, Arthur M. Wolfe
The discovery of metal-poor stars (where metal is any element more massive than helium) has enabled astronomers to probe the chemical enrichment history of the Milky Way. More rece…
On the Origin of the High-Ionization Intermediate-Velocity Gas Toward HD 14434
David C. Knauth, J. Christopher Howk, Kenneth R. Sembach +2
We present Far Ultraviolet Spectroscopic Explorer and Space Telescope Imaging Spectrograph observations of high-ionization interstellar absorption toward HD 14434 [(l, b) = (135.1,…
Oxygen Gas Phase Abundance Revisited
M. K. André, C. M. Oliveira, J. C. Howk +7
We present new measurements of the interstellar gas-phase oxygen abundance along the sight lines towards 19 early-type galactic stars at an average distance of 2.6 kpc. We derive O…