Search Publications
The Disk and Environment of the Herbig Be Star HD 100546
Gull, T. R.; Moos, H. W.; Stecklum, B. +26 more
Coronagraphic imaging of the nearest Herbig Be star with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope, Ks (2.15 µm) imaging with ADONIS at the 3.6 m telescope at La Silla, and mid-infrared imaging with OSCIR using the 4 m Blanco Telescope at Cerro Tololo Inter-American Observatory confirm the detection …
The Asymmetric Nebula Surrounding the Extreme Red Supergiant VY Canis Majoris
Smith, Nathan; Gehrz, Robert D.; Humphreys, Roberta M. +3 more
We present HST/WFPC2 images plus ground-based infrared images and photometry of the very luminous OH/IR star VY Canis Majoris. Our WFPC2 data show a complex distribution of knots and filamentary arcs in the asymmetric reflection nebula around the obscured central star. The reflection arcs may result from multiple, asymmetric ejection episodes due …
The Chandra Deep Survey of the Hubble Deep Field North Area. IV. An Ultradeep Image of the HDF-N
Hornschemeier, A. E.; Alexander, D. M.; Brandt, W. N. +7 more
We present results from a 479.7 ks Chandra exposure of the Hubble Deep Field North (HDF-N) and its immediate vicinity. In this X-ray image, the deepest ever reported with a 0.5-2.0 keV flux limit of ~4.9×10-17 ergs cm-2 s-1, four new HDF-N X-ray sources are detected, bringing the total number of such sources to 12.…
The Fossil Starburst in M82
de Grijs, Richard; O'Connell, Robert W.; Gallagher, John S., III
We present high-resolution HST imaging in the optical (WFPC2) and near-infrared (NICMOS) of a disk region 1 kpc northeast of the starburst core in the nearby galaxy M82. This region, M82 ``B,'' has been suspected to be a fossil starburst site in which an intense episode of star formation occurred over 100 Myr ago, and our new observations confirm …
Dusty Nuclear Disks and Filaments in Early-Type Galaxies
Jaffe, W.; Ford, H. C.; van den Bosch, F. C. +4 more
We examine the dust properties of a nearby distance-limited sample of early-type galaxies using WFPC2 of the Hubble Space Telescope. Dust is detected in 29 out of 67 galaxies (43%), including 12 with small nuclear dusty disks. In a separate sample of 40 galaxies biased for the detection of dust by virtue of their detection in IRAS 100 µm ban…
Spectrophotometric Standards from the Far-Ultraviolet to the Near-Infrared: STIS and NICMOS Fluxes
Calzetti, D.; Dickinson, M. E.; Bohlin, R. C.
With photometric repeatability in the 0.2%-0.4% range and wavelength coverage from 1150 to 10,200 Å, the Space Telescope Imaging Spectrograph (STIS) low-dispersion spectrophotometry provides excellent absolute flux standards. STIS observations of 19 stars are used to update the database of Hubble Space Telescope standard stars with absolute fluxes…
New Insights on the Draco Dwarf Spheroidal Galaxy from the Sloan Digital Sky Survey: A Larger Radius and No Tidal Tails
Grebel, Eva K.; York, Donald G.; Holtzman, Jon +20 more
We have investigated the spatial extent and structure of the Draco dwarf spheroidal galaxy by using deep wide-field multicolor CCD photometry from the Sloan Digital Sky Survey (SDSS). Our study covers an area of 27 deg2 around the center of the Draco dwarf and reaches 2 mag below the level of Draco's horizontal branch. The SDSS photomet…
The Line-of-Sight Depth of Populous Clusters in the Small Magellanic Cloud
Piatti, Andrés E.; Sarajedini, Ata; Geisler, Doug +4 more
We present an analysis of age, metal abundance, and positional data on populous clusters in the Small Magellanic Cloud (SMC) with the ultimate aim of determining the line-of-sight (LOS) depth of the SMC by using these clusters as proxies. Our data set contains 12 objects and is limited to clusters with the highest-quality data for which the ages a…
The Shape and Orientation of the Homunculus Nebula Based on Spectroscopic Velocities
Hillier, D. J.; Smith, Nathan; Gull, Theodore R. +2 more
Doppler velocities give information about the three-dimensional shape and orientation of the bipolar ejecta of η Car. We report slit spectroscopy obtained using the Space Telescope Imaging Spectrograph (HST/STIS), with spatial resolution adequate for good models. These data allow an independent estimate of the distance to this object. Equatorial v…
An Abundance Analysis for Four Red Horizontal-Branch Stars in the Extremely Metal-Rich Globular Cluster NGC 6528
Cohen, Judith G.; Carretta, Eugenio; Gratton, Raffaele G. +1 more
We present the results of the first analysis of high-dispersion spectra of four red horizontal-branch stars in the metal-rich globular cluster NGC 6528, located in Baade's window. We find that the mean [Fe/H] for NGC 6528 is +0.07+/-0.01 dex (error of the mean), with a star-to-star scatter of σ=0.02 dex (four stars), although the total error is li…