Search Publications
WFPC2 Images of the Central Regions of Early-Type Galaxies. I. The Data
van den Bosch, Frank C.; Rest, Armin; Ford, Holland C. +5 more
We present high-resolution R-band images of the central regions of 67 early-type galaxies obtained with the Wide Field and Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope (HST). This homogeneously selected sample roughly doubles the number of early-type galaxies that have now been imaged at HST resolution and complements similar data …
A Search for L Dwarf Binary Systems
Kirkpatrick, J. Davy; Gizis, John E.; Reid, I. Neill +1 more
We present analysis of Hubble Space Telescope (HST) planetary camera images of 20 L dwarfs identified in the course of the Two Micron All Sky Survey. Four of the targets, 2MASSW J0746425+200032, 2MASSs J0850359+105716, 2MASSW J0920122+351742, and 2MASSW J1146345+223053, have faint red companions at separations between 0.07" and 0.29" (1.6-7.6 AU).…
The Expansion Center and Dynamical Age of the Galactic Supernova Remnant Cassiopeia A
Thorstensen, John R.; van den Bergh, Sidney; Fesen, Robert A.
We present proper motions for 21 bright main shell and 17 faint, higher velocity, outer ejecta knots in the Cas A supernova remnant and use them to derive new estimates for the remnant's expansion center and age. Our study included 1951-1976 Palomar 5 m prime focus plates, 1988-1999 CCD images from the KPNO 4 m and MDM 2.4 m telescopes, and 1999 H…
High-Mass, OB Star Formation in M51: Hubble Space Telescope Hα and Paα Imaging
Scoville, N. Z.; Polletta, M.; Thompson, R. +3 more
We have obtained Hα and Paα emission-line images covering the central 3'-4' of M51 using the WFPC2 and NICMOS instruments on the Hubble Space Telescope to study the high-mass stellar population. The 0.1"-0.2" pixels provide 4.6-9 pc resolution in M51, and the Hα/Paα line ratios are used to obtain extinction estimates. A sample of 1373 Hα emission …
Central Structural Parameters of Early-Type Galaxies as Viewed with Nicmos on the Hubble Space Telescope
Ravindranath, Swara; Filippenko, Alexei V.; Ho, Luis C. +2 more
We present surface photometry for the central regions of a sample of 33 early-type (E, S0, and S0/a) galaxies observed at 1.6 µm (H band) using the Hubble Space Telescope. Dust absorption has less of an impact on the galaxy morphologies in the near-infrared than found in previous work based on observations at optical wavelengths. When presen…
Mayall II=G1 in M31: Giant Globular Cluster or Core of a Dwarf Elliptical Galaxy?
Djorgovski, S. G.; Jablonka, P.; Sarajedini, A. +3 more
Mayall II=G1 is one of the brightest globular clusters belonging to M31, the Andromeda galaxy. Our observations with the Wide Field and Planetary Camera (WFPC2) on board the Hubble Space Telescope (HST) provide photometric data for the I versus V-I and V versus V-I color-magnitude diagrams. They reach stars with magnitudes fainter than V=27 mag, w…
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 …