Search Publications
Blue Luminous Stars in Nearby Galaxies: Quantitative Spectral Analysis of M33 B-Type Supergiant Stars
Smartt, S. J.; Lennon, D. J.; Herrero, A. +5 more
We present the detailed spectral analysis of a sample of M33 B-type supergiant stars, aimed at the determination of their fundamental parameters and chemical composition. The analysis is based on a grid of non-LTE metal line-blanketed model atmospheres including the effects of stellar winds and spherical extension computed with the code FASTWIND. …
Stellar and Total Mass in Early-Type Lensing Galaxies
Saha, Prasenjit; Ferreras, Ignacio; Williams, Liliya L. R.
For 18 well-observed gravitationally lensed QSOs, we compare new nonparametric mass profiles for the lensing galaxies with stellar population models derived from published Hubble Space Telescope photometry. The large volume of parameter space searched-with respect to the possible star formation histories-allows us to infer robust estimates and unc…
A Chandra HETGS Spectral Study of the Iron K Bandpass in MCG -6-30-15: A Narrow View of the Broad Iron Line
Young, A. J.; Fabian, A. C.; Reynolds, C. S. +3 more
We present a high-resolution X-ray spectrum of the iron K bandpass in MCG -6-30-15 based on a 522 ks observation with Chandra's High Energy Transmission Grating Spectrometer (HETGS). The Chandra spectrum is consistent with the presence of a relativistically broadened, highly redshifted iron Kα emission line with a profile similar to previous obser…
Kinematics of Low-z Ultraluminous Infrared Galaxies and Implications for Dynamical Mass Derivations in High-z Star-forming Galaxies
Arribas, Santiago; Colina, Luis; Monreal-Ibero, A.
The kinematic properties of the gaseous and stellar components of 11 ultraluminous infrared galaxies (ULIRGs; 14 nuclei) are investigated by means of integral field spectroscopy (IFS) with the INTEGRAL system and available IR and CO millimeter spectroscopy. The sample of ULIRGs cover different phases of the merging process and span all levels of a…
Predicting QSO Continua in the Lyα Forest
O'Meara, John M.; Tytler, David; Lubin, Dan +2 more
We present a method to make predictions with sets of correlated data values, in this case QSO flux spectra. We predict the continuum in the Lyα forest of a QSO, from 1020 to 1216 Å, using the spectrum of that QSO from 1216 to 1600 Å. We find correlations between the unabsorbed flux in these two wavelength regions in the Hubble Space Telescope (HST…
The Fundamental Plane of Cluster Elliptical Galaxies at z=1.25
Rosati, P.; Rix, H. -W.; van der Wel, A. +8 more
Using deep Hubble Space Telescope Advanced Camera for Surveys imaging and Very Large Telescope FOcal Reducer/low dispersion Spectrograph 2 spectra, we determined the velocity dispersions, effective radii, and surface brightnesses for four early-type galaxies in the z=1.237 cluster RDCS 1252.9-2927. All four galaxies are massive, greater than 10
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…