Search Publications
Color-Magnitude Diagram and Luminosity Function of M4 near the Hydrogen-burning Limit
Anderson, Jay; Bedin, Luigi R.; Piotto, Giampaolo +1 more
A proper-motion separation of M4 members from field stars, using deep Hubble Space Telescope observations separated by a time baseline of 5 yr, allows us to study a pure sample of cluster main-sequence stars almost to the minimum mass for hydrogen burning. High-precision photometry shows how badly current theoretical models fail to reproduce the c…
The Multitude of Unresolved Continuum Sources at 1.6 Microns in Hubble Space Telescope Images of Seyfert Galaxies
Rieke, G. H.; Alonso-Herrero, A.; Quillen, A. C. +4 more
We examine 112 Seyfert galaxies observed by the Hubble Space Telescope at 1.6 µm. We find that ~50% of the Seyfert 2.0 galaxies which are part of the Revised Shapely-Ames (RSA) Catalog or the CfA redshift sample contain unresolved continuum sources at 1.6 µm. All but a couple of the Seyfert 1.0-1.9 galaxies display unresolved continuum…
B1359+154: A Six-Image Lens Produced by a z ~= 1 Compact Group of Galaxies
Peng, C. Y.; Keeton, C. R.; Kochanek, C. S. +8 more
Hubble Space Telescope (HST) V- and I-band observations show that the gravitational lens B1359+154 consists of six images of a single zs=3.235 radio source and its star-forming host galaxy, produced by a compact group of galaxies at zl~=1. Very Long Baseline Array (VLBA) observations at 1.7 GHz strongly support this conclusio…
Far Ultraviolet Spectroscopic Explorer Observations of Molecular Hydrogen in Translucent Interstellar Clouds. II. The Line of Sight toward HD 110432
York, Donald G.; Roueff, E.; Shull, J. Michael +7 more
We report the second study from the FUSE survey of molecular hydrogen in translucent clouds for the line of sight toward HD 110432. This star lies beyond the Coalsack dark nebula, and, with E(B-V)=0.40 and AV=1.32, this line of sight bridges the gap between less-extinguished diffuse-cloud lines of sight with AV~1, such as ζ O…
The Infrared Surface Brightness Fluctuation Hubble Constant
Lauer, Tod R.; Ajhar, Edward A.; Rieke, Marcia J. +5 more
We measured infrared surface brightness fluctuation (SBF) distances to an isotropically distributed sample of 16 distant galaxies with redshifts reaching 10,000 km s-1 using the near-IR camera and multiobject spectrometer (NICMOS) on the Hubble Space Telescope (HST). The excellent spatial resolution, very low background, and brightness …
Star Formation History in the NICMOS Northern Hubble Deep Field
Thompson, Rodger I.; Weymann, Ray J.; Storrie-Lombardi, Lisa J.
We present the results of an extensive analysis of the star formation rates determined from the NICMOS deep images of the northern Hubble Deep Field. We use SED template fitting photometric techniques to determine both the redshift and the extinction for each galaxy in our field. Measurement of the individual extinctions provides a correction for …
A Revised Cepheid Distance to NGC 4258 and a Test of the Distance Scale
Zepf, Stephen E.; Davis, Marc; Madore, Barry F. +5 more
In a previous paper we reported a Hubble Space Telescope (HST) Cepheid distance to the galaxy NGC 4258 obtained using the calibrations and methods then standard for the Key Project. Here we reevaluate the Cepheid distance using the recently revised Key Project procedures. These revisions alter the zero points and slopes of the Cepheid period-lumin…
Morphology and Evolution of the Large Magellanic Cloud Planetary Nebulae
Mutchler, Max; Blades, J. Chris; Balick, Bruce +2 more
The LMC is ideal for studying the coevolution of planetary nebulae (PNs) and their central stars in that the debilitating uncertainties of the Galactic PN distance scale and selection biases from attenuation by interstellar dust do not apply. We present images and analyze slitless spectra that were obtained in a survey of Large Magellanic Cloud PN…
The Jet and the Supernova in GRB 990712
Christensen, L.; Hjorth, J.; Jakobsson, P. +2 more
The optical light curve of the afterglow following the gamma-ray burst GRB 990712 is reexamined. Recently published polarization measurements of that source require a collimated outflow geometry that in turn predicts a break in the light curve. We show that the V-band light curve is consistent with such a break and that the postbreak light-curve e…
The Rich Ultraviolet Spectrum of Vibrationally Excited Interstellar H2 toward HD 37903
Sofia, Ulysses J.; Meyer, David M.; Draine, B. T. +2 more
Based on recent high-resolution Hubble Space Telescope Space Telescope Imaging Spectrograph observations over the 1160-1360 Å wavelength region, we have discovered that HD 37903 (the illuminating star of the bright reflection nebula NGC 2023 in Orion) exhibits a rich spectrum of vibrationally excited interstellar H2 absorption. We have …