Search Publications
Young Super Star Clusters in the Starburst of M82: The Catalog
Tenorio-Tagle, G.; Melo, V. P.; Muñoz-Tuñón, C. +1 more
Recent results from the Hubble Space Telescope (HST) have resolved starbursts as collections of compact young stellar clusters. Here we present a photometric catalog of the young stellar clusters in the nuclear starburst of M82, observed with the HST WFPC2 in Hα (F656N) and in four optical broadband filters. We identify 197 young super stellar clu…
Rapid Penumbral Decay Associated with an X2.3 Flare in NOAA Active Region 9026
Liu, Chang; Yang, Guo; Denker, Carsten +2 more
We present observations of rapid penumbral decay associated with a major flare in solar NOAA Active Region 9026 on 2000 June 6. Within 1.5 hr, an X2.3 flare accompanied by an 11° long filament eruption and a full-halo coronal mass ejection (CME) originated near the neutral line of a large δ-spot region, which was associated with significant change…
Ice Age Epochs and the Sun's Path through the Galaxy
Gies, D. R.; Helsel, J. W.
We present a calculation of the Sun's motion through the Milky Way over the last 500 million yr. The integration is based on estimates of the Sun's current position and speed from measurements with Hipparcos and on a realistic model for the Galactic gravitational potential. We estimate the times of the Sun's past spiral arm crossings for a range o…
Optical Morphology Evolution of Infrared Luminous Galaxies in GOODS-N
Le Floc'h, E.; Koo, D. C.; Melbourne, J.
We combine optical morphologies and photometry from HST, redshifts from Keck, and mid-infrared luminosities from Spitzer for an optically selected sample of ~800 galaxies in GOODS-N to track the morphology evolution of luminous infrared galaxies (LIRGs) since redshift z=1. We find a 50% decline in the number of LIRGs from z~1 to lower redshift, in…
Gamma-Ray Burst-Selected High-Redshift Galaxies: Comparison to Field Galaxy Populations to z ~ 3
Kouveliotou, C.; Fruchter, A. S.; Vreeswijk, P. M. +6 more
We study the internal structural properties of 37 long-duration gamma-ray burst (GRB) host galaxies imaged with the Hubble Space Telescope (HST). Our goal is to gain insights in the types of galaxies that give rise to GRBs and the relationship of GRB hosts to high-redshift galaxies selected through more traditional photometric methods. We measure …
The Advanced Camera for Surveys Virgo Cluster Survey. V. Surface Brightness Fluctuation Calibration for Giant and Dwarf Early-Type Galaxies
Jordán, Andrés; Tonry, John L.; Côté, Patrick +7 more
As part of the Advanced Camera for Surveys (ACS) Virgo Cluster Survey, we have measured surface brightness fluctuations (SBFs) in a sample of 100 early-type Virgo galaxies. Distances derived from these measurements are needed to explore the three-dimensional structure of the Virgo Cluster, study the intrinsic parameters of globular clusters associ…
Calculating the Thermal Structure of Solar Active Regions in Three Dimensions
Linker, Jon A.; Mikić, Zoran; Mok, Yung +1 more
We describe a technique to obtain the temperature and density distribution in an active region for a specified plasma heating model. The technique can be applied in general to determine the magnetic field and thermal structure self-consistently. For simplicity, we illustrate the application of this technique in the limit of small plasma β, in whic…
GEMS: Which Galaxies Dominate the z~0.7 Ultraviolet Luminosity Density?
Heymans, C.; Wolf, C.; Barden, M. +14 more
We combine high-resolution images from GEMS with redshifts and spectral energy distributions from COMBO-17 to explore the morphological types of galaxies that dominate the z~0.7 UV luminosity density. We analyzed rest-frame 280 nm and V-band luminosities of 1483 galaxies with 0.65<z<0.75, combining these with visual morphological classificat…
Star Formation Rates in Cooling Flow Clusters: A UV Pilot Study with Archival XMM-Newton Optical Monitor Data
Mushotzky, R.; Hicks, A. K.
We have analyzed XMM-Newton Optical Monitor UV (180-400 nm) data for a sample of 33 galaxies. Thirty are cluster member galaxies, and nine are central cluster galaxies (CCGs) in cooling flow clusters having mass deposition rates between 8 and 525 Msolar yr-1. By comparing the ratio of UV to 2MASS J-band fluxes, we find a sign…
Molecular Hydrogen in the Damped Lyα Absorber of Q1331+170
Ge, Jian; Meyer, David M.; Bechtold, Jill +1 more
We used HST STIS to obtain the spectrum of molecular hydrogen associated with the damped Lyα system at zabs=1.7765 toward the quasar Q1331+170 at zem=2.084. Strong H2 absorption was detected, with a total H2 column density of N(H2)=(4.45+/-0.36)×1019 cm-2. The molecular h…