Search Publications
Solar Type II Radio Bursts and IP Type II Events
Cane, H. V.; Erickson, W. C.
We have examined radio data from the WAVES experiment on the Wind spacecraft in conjunction with ground-based data in order to investigate the relationship between the shocks responsible for metric type II radio bursts and the shocks in front of coronal mass ejections (CMEs). The bow shocks of fast, large CMEs are strong interplanetary (IP) shocks…
Solar Convection-Zone Dynamics, 1995-2004
Thompson, M. J.; Howe, R.; Komm, R. +3 more
The nine-year span of medium-degree helioseismic data from the Global Oscillation Network Group (GONG) and the Michelson Doppler Imager (MDI) allows us to study the evolving zonal flows in the solar convection zone over the rising phase, maximum, and early declining phase of solar cycle 23. Using two independent two-dimensional rotation inversion …
XMM-Newton Observations of Ultraluminous X-Ray Sources in Nearby Galaxies
Feng, Hua; Kaaret, Philip
We examined X-ray spectral and timing properties of ultraluminous X-ray sources (ULXs) in nearby galaxies in XMM-Newton archival data. There appear to be three distinct classes of spectra. One class shows emission from hot, diffuse plasma. This thermal emission is similar to that seen from recent supernovae; the temperatures are in the range 0.6-0…
Highly Ionized High-Velocity Clouds: Hot Intergalactic Medium or Galactic Halo?
Shull, J. Michael; Giroux, Mark L.; Collins, Joseph A.
We use spectroscopic data from the Hubble Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) to study the wide range of ionization states of the ``highly ionized high-velocity clouds'' (HVCs). Studied extensively in O VI absorption, these clouds are usually assumed to be infalling gas in the Galactic halo at distances less tha…
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…