Search Publications
The Chemical Properties of Low-redshift QSOs
Nagao, Tohru; Kim, Sang Chul; Woo, Jong-Hak +1 more
We investigate the chemical properties of low-z QSOs, using archival UV spectra obtained with the Hubble Space Telescope and International Ultraviolet Explorer for a sample of 70 Palomar-Green QSOs at z < 0.5. By utilizing the flux ratios of UV emission lines (i.e., N V/C IV, (Si IV+O IV])/C IV, and N V/He II) as metallicity indicators, we comp…
The Surprising Absence of Absorption in the Far-ultraviolet Spectrum of Mrk 231
Lutz, D.; Genzel, R.; Maiolino, R. +11 more
Mrk 231, the nearest (z = 0.0422) quasar, hosts both a galactic-scale wind and a nuclear-scale iron low-ionization broad absorption line (FeLoBAL) outflow. We recently obtained a far-ultraviolet (FUV) spectrum of this object covering ~1150-1470 Å with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. This spectrum is highly pecu…
Galaxy Interactions in Compact Groups. I. The Galactic Winds of HCG16
Kewley, Lisa J.; Dopita, Michael A.; Vogt, Frédéric P. A.
Using the WiFeS integral field spectrograph, we have undertaken a series of observations of star-forming galaxies in compact groups. In this first paper dedicated to the project, we present the analysis of the spiral galaxy NGC 838, a member of the Hickson Compact Group 16, and of its galactic wind. Our observations reveal that the wind forms an a…
Magnetic Structure Producing X- and M-class Solar Flares in Solar Active Region 11158
Choe, G. S.; Shiota, D.; Inoue, S. +2 more
We study the three-dimensional magnetic structure of the solar active region 11158, which produced one X-class and several M-class flares on 2011 February 13-16. We focus on the magnetic twist in four flare events, M6.6, X2.2, M1.0, and M1.1. The magnetic twist is estimated from the nonlinear force-free field extrapolated from the vector fields ob…
The Recurrent Nova T Pyx: Distance and Remnant Geometry from Light Echoes
Sokoloski, J. L.; Crotts, Arlin P. S.; Lawrence, Stephen +1 more
The recurrent nova T Pyxidis (T Pyx) is well known for its small binary separation, its unusually high luminosity in quiescence, and the spectacular Hubble Space Telescope (HST) images of its surrounding remnant. In 2011 April, T Pyx erupted for the first time since 1966. Here we describe HST observations in late 2011 of a transient reflection neb…
Herschel Observations of the W3 GMC: Clues to the Formation of Clusters of High-mass Stars
Martin, P. G.; Hill, T.; White, G. J. +22 more
The W3 GMC is a prime target for the study of the early stages of high-mass star formation. We have used Herschel data from the HOBYS key program to produce and analyze column density and temperature maps. Two preliminary catalogs were produced by extracting sources from the column density map and from Herschel maps convolved to 500 µm resol…
A Double White-dwarf Cooling Sequence in ω Centauri
Salaris, M.; Anderson, J.; Bergeron, P. +4 more
We have applied our empirical-point-spread-function-based photometric techniques on a large number of calibration-related WFC3/UVIS UV-B exposures of the core of ω Cen, and found a well-defined split in the bright part of the white-dwarf cooling sequence (WDCS). The redder sequence is more populated by a factor of ~2. We can explain the separation…
Diagnosing the Time Dependence of Active Region Core Heating from the Emission Measure. II. Nanoflare Trains
Klimchuk, J. A.; Reep, J. W.; Bradshaw, S. J.
The time dependence of heating in solar active regions can be studied by analyzing the slope of the emission measure distribution coolward of the peak. In a previous study we showed that low-frequency heating can account for 0% to 77% of active region core emission measures. We now turn our attention to heating by a finite succession of impulsive …
SPT 0538-50: Physical Conditions in the Interstellar Medium of a Strongly Lensed Dusty Star-forming Galaxy at z = 2.8
Bock, J. J.; Ibar, E.; Murphy, E. J. +38 more
We present observations of SPT-S J053816-5030.8, a gravitationally lensed dusty star-forming galaxy (DSFG) at z = 2.7817 that was first discovered at millimeter wavelengths by the South Pole Telescope. SPT 0538-50 is typical of the brightest sources found by wide-field millimeter-wavelength surveys, being lensed by an intervening galaxy at moderat…
Very Large Array Mapping of the CO(1-0) Line in SMM J14011+0252
Baker, Andrew J.; Harris, Andrew I.; Sharon, Chelsea E. +1 more
We present high-resolution CO(1-0) observations of the lensed submillimeter galaxy (SMG) SMM J14011+0252 at z = 2.6. Comparison to the previously detected CO(3-2) line gives an intensity ratio of r 3, 1 = 0.97 ± 0.16 in temperature units, larger than is typical for SMGs but within the range seen in the low-z ultraluminous infrared galax…