Search Publications
Spectroscopic Redshifts for Seven Lens Galaxies
Maoz, Dan; Rix, Hans-Walter; Kochanek, Christopher S. +2 more
The use of gravitationally lensed quasars for cosmological applications and as probes of galaxy structure and evolution requires knowledge about the lens redshift, which is unknown for a large fraction of lenses. We report Very Large Telescope observations of 11 lensed quasars, designed to measure the redshifts of their lens galaxies. We successfu…
Kinematics of Interstellar Gas in Nearby UV-selected Galaxies Measured with HST STIS Spectroscopy
Leitherer, C.; Oey, M. S.; Heckman, T. M. +3 more
We measure Doppler shifts of interstellar absorption lines in HST STIS spectra of individual star clusters in nearby UV-selected galaxies. Values for systemic velocities, which are needed to quantify outflow speeds, are taken from the literature and verified with stellar lines. We detect outflowing gas in 8 of 17 galaxies via low-ionization lines …
Warm Water Vapor around Sagittarius B2
Cernicharo, José; Goicoechea, Javier R.; Pardo, Juan R. +1 more
Several condensations heated externally by nearby hot stars are present in the Sgr B2 region for which H2O far-IR lines are expected to probe only an external low-density and high temperature section. Millimeter-wave lines can penetrate deeper into them (higher densities and lower Tk). We have conducted a study combining H
Luminous Compact Blue Galaxies up to z~1 in the Hubble Space Telescope Ultra Deep Field. I. Small Galaxies or Blue Centers of Massive Disks?
Koo, D. C.; Melbourne, J.; Willmer, C. N. A. +4 more
We analyze 26 luminous compact blue galaxies (LCBGs) in the Hubble Space Telescope ACS Ultra Deep Field (UDF) at z~0.2-1.3, to determine whether these truly are small galaxies or, rather, bright central starbursts within existing or forming large disk galaxies. Surface brightness profiles from UDF images reach fainter than rest-frame 26.5 B mag ar…
Sources of the Solar Wind at Ulysses during 1990-2006
Sheeley, N. R., Jr.; Wang, Y. -M.
The Ulysses spacecraft is now well into its third polar orbit around the Sun. Using stackplot displays, we summarize the wind speeds and interplanetary sector polarities recorded by Ulysses since its launch in 1990 and relate the observed patterns to the global evolution of open magnetic regions (coronal holes) over the solar cycle. We verify that…
Halo Structures of Gravitational Lens Galaxies
Kochanek, Christopher S.; Falco, Emilio E.; Yoo, Jaiyul +1 more
We explore the halo structure of four gravitational lenses with well-observed, thin Einstein rings. We find that the gravitational potentials are well described by ellipsoidal density distributions in the sense that the best-fit nonellipsoidal models have parameters consistent with their ellipsoidal counterparts. We find upper limits on the standa…
High Spatial Resolution T-ReCS Mid-Infrared Imaging of Luminous Infrared Galaxies
Colina, Luis; Rieke, George H.; Alonso-Herrero, Almudena +4 more
We present diffraction-limited (FWHM~0.3") Gemini/T-ReCS mid-infrared (MIR; N-band or narrowband at 8.7 µm) imaging of four luminous infrared galaxies (LIRGs) drawn from a representative local sample. The MIR emission in the central few kiloparsecs is strikingly similar to that traced by Paα and generally consists of bright nuclear emission …
A Massive Bipolar Outflow and a Dusty Torus with Large Grains in the Preplanetary Nebula IRAS 22036+5306
Sahai, R.; Sánchez Contreras, C.; Patel, N. A. +2 more
We report high angular resolution (~1") CO J=3-2 interferometric mapping using the Submillimeter Array (SMA) of IRAS 22036+5306 (I22036), a bipolar preplanetary nebula (PPN) with knotty jets discovered in our HST snapshot survey of young PPNs. In addition, we have obtained supporting lower resolution (~10") CO and 13CO J=1-0 observation…
Flux Rope Model of the 2003 October 28-30 Coronal Mass Ejection and Interplanetary Coronal Mass Ejection
Chen, J.; Yurchyshyn, V. B.; Skoug, R. M. +2 more
A numerical model of an erupting solar flux rope is shown to reproduce both quantitative near-Sun properties of the 2003 October 28 coronal mass ejection and the timing, strength, and orientation of the fields measured in situ at 1 AU. Using a simple erupting flux rope model, we determine the best-fit parameters for this event. Our analysis shows …
Observed Frequency Variations of Solar p-Mode Travel Times as Evidence for Surface Effects in Sunspot Seismology
Birch, A. C.; Braun, D. C.
Using helioseismic holography, we measure acoustic (p-mode) travel-time perturbations, observed within solar active regions, as functions of frequency and phase speed. We find evidence for a frequency variation, at fixed phase speed, of the travel times that has not previously been reported. This variation is not expected from typical sound-speed …