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Stellar populations and surface brightness fluctuations: new observations and models
Vazdekis, Alexandre; Ajhar, Edward A.; Blakeslee, John P.
We investigate the use of surface brightness fluctuations (SBF) measurements in optical and near-IR bandpasses for both stellar population and distance studies. New V-band SBF data are reported for five galaxies in the Fornax cluster and combined with literature data to define a V-band SBF distance indicator, calibrated against Cepheid distances t…
On the Origin of Intrinsic Narrow Absorption Lines in z<~1 QSOS
Charlton, Jane C.; Brandt, W. N.; Churchill, Christopher W. +3 more
We present an exhaustive statistical analysis of the associated (Δvabs<5000 km s-1), high-ionization (C IV, N V, O VI) narrow absorption line (NAL) systems in a sample of 59 QSOs defined from the Hubble Space Telescope (HST) QSO Absorption Line Key Project. The goals of the research were twofold: (1) to determine the frequ…
Luminosity Evolution of Field Early-Type Galaxies to Z=0.55
van Dokkum, Pieter G.; Franx, Marijn; Kelson, Daniel D. +1 more
We study the fundamental plane (FP) of field early-type galaxies at intermediate redshift, using Hubble Space Telescope Wide Field Planetary Camera 2 observations and deep Keck spectroscopy. Structural parameters and internal velocity dispersions are measured for 18 galaxies at 0.15<z<0.55. Rest-frame M/LB ratios are determined fr…
Deep Hubble Space Telescope Imaging of IC 1613. I. Variable Stars and Distance
Dolphin, Andrew E.; Skillman, Evan D.; Saha, A. +6 more
We present WFPC2 VI photometry of a field in the halo of IC 1613, finding 13 RR Lyrae stars and 11 Cepheids. Our photometry of the red giant branch tip and red clump is used to derive distances to IC 1613, which are consistent with each other and with distances based on the variable stars. We compare these values with similarly measured distances …
Search for NH3 ice in cold dust envelopes around YSOs
Dartois, E.; d'Hendecourt, L.
We present a study of the 3.1 micron absorption band, attributed to the OH stretching mode of the water molecule in the form of solid ice, observed in many protostellar lines of sight by the SWS instrument on board ISO. Using ice optical constants and Mie theory, we obtain reasonable fits to the peculiar band shapes observed in twelve sources. The…
A Low Global Star Formation Rate in the Rich Galaxy Cluster AC 114 at z=0.32
Smail, Ian; Glazebrook, Karl; Balogh, Michael L. +3 more
We present the results of a wide-field survey for Hα-emitting galaxies in the cluster AC 114 at z=0.32. Spectra centered on Hα at the cluster redshift have been obtained for 586 galaxies to Itot~22 out to a radius of ~2 h-150 Mpc. At most, only ~10% of these were found to be Hα-emitting cluster members. These objec…
Substantial reservoirs of molecular hydrogen in the debris disks around young stars
Thi, W. F.; Natta, A.; van Dishoeck, E. F. +7 more
Circumstellar accretion disks transfer matter from molecular clouds to young stars and to the sites of planet formation. The disks observed around pre-main-sequence stars have properties consistent with those expected for the pre-solar nebula from which our own Solar System formed 4.5Gyr ago. But the `debris' disks that encircle more than 15% of n…
Models for Multiband Infrared Surveys
Xu, Cong; Shupe, David L.; Lonsdale, Carol J. +2 more
Empirical ``backward'' galaxy evolution models for IR bright galaxies are constrained using multiband IR surveys. A new Monte Carlo algorithm is developed for this task. It exploits a large library of realistic spectral energy distributions (SEDs) of 837 local IR galaxies (IRAS 25 µm selected) from the UV (1000 Å) to the radio (20 cm), inclu…
The Statistical and Physical Properties of the Low-Redshift LYα Forest Observed with the Hubble Space Telescope/STIS
Tripp, Todd M.; Davé, Romeel
We examine the Lyα absorber population at z<0.3 detected in spectra of the quasars PG 0953+415 and H1821+643 taken with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We compare their statistical properties to those in carefully constructed mock quasar spectra drawn from a cosmological hydrodynamic simulation of a…
A Study of the Stability of Jovian Zonal Winds from HST Images: 1995-2000
Sánchez-Lavega, A.; García-Melendo, E.
We present a five-year study of the temporal stability of Jupiter's zonal wind velocity profile at cloud level based on Hubble Space Telescope images obtained from 1995 to 2000. We used the correlation of east-west albedo scans in pairs of images separated by one jovian rotation to retrieve the zonal winds. The resolution in the HST images ranged …