Search Publications
Hubble Space Telescope NICMOS Imaging of the Core of M87
Rieke, Marcia J.; Corbin, Michael R.; O'Neil, Earl
We present broadband 1.1, 1.6, and 2.2 µm images and a 2.37 µm narrowband image of the inner 19" of the nearby radio galaxy M87, obtained with the Near Infrared Camera and Multi-Object Spectrometer of the Hubble Space Telescope (HST). The isophotes of the broadband images are almost perfectly circular to within approximately 0.5" (~50 …
The Nature of [Ar III]-Bright Knots in the Crab Nebula
Fesen, Robert A.; Schaller, Emily L.
The kinematic and morphological properties of a string of [Ar III]-bright knots in the Crab Nebula are examined using 1994-1999 Hubble Space Telescope (HST) Wide Field Planetary Camera 2 images of the remnant. We find that five southern [Ar III]-bright knots exhibit ordinary radial motions away from the nebula's center of expansion with magnitudes…
A Polarimetric Survey for Dust in 47 Tucanae
Forte, Juan C.; Vega, E. Irene; Cellone, Sergio A. +3 more
We present linear polarization measurements in the V band for 77 stars in the field of the globular cluster 47 Tucanae (NGC 104) and for 14 regions free of bright stars, located along an elliptical isophotal contour of the cluster, as well as UBVRI measurements for the cluster nucleus. The observations show variable foreground polarization that, o…
Infrared Space Observatory Polarimetric Imaging of the Egg Nebula (RAFGL 2688)
Kastner, Joel H.; Siebenmorgen, Ralf; Li, Jingqiang +1 more
We present polarimetric imaging of the protoplanetary nebula RAFGL 2688 obtained at 4.5 µm with the Infrared Space Observatory (ISO). We have deconvolved the images to remove the signature of the point spread function of the ISO telescope, to the extent possible. The deconvolved 4.5 µm image and polarimetric map reveal a bright point s…
Star Formation in the radio galaxy NGC 4410A
Donahue, Megan; Stocke, John T.; Smith, Beverly J.
The NGC 4410 group of galaxies provides us with a rare opportunity to study a nearby (97 h-175 Mpc) example of a radio galaxy (NGC 4410A) embedded in an extended X-ray source, with evidence for star formation that can be readily spatially distinguished from regions dominated by the active galactic nucleus and shocks. We prese…
Galaxy Morphology in the Rich Cluster Abell 2390
Saintonge, A.; Hutchings, J. B.; Schade, D. +1 more
We have analyzed images of the field of Abell 2390 obtained with the Canada-France-Hawaii Telescope and the Hubble Space Telescope. The analysis fits models to bulge and disk components of several hundred galaxies, with about equal samples from the cluster and field. We also have assessed and graded asymmetries in the images. The cluster galaxies …
Properties of Globular Cluster Systems in Nearby Early-Type Galaxies
Forbes, Duncan A.; Brodie, Jean P.; Huchra, John P. +2 more
We present a study of globular clusters (GCs) in 17 relatively nearby early-type galaxies, based on deep F555W and F814W images from the Wide Field Planetary Camera 2, on board the Hubble Space Telescope. A detailed analysis of color distributions, cluster sizes, and luminosity functions is performed and compared with GCs in the Milky Way. In near…
New Insights from HST Studies of Globular Cluster Systems. I. Colors, Distances, and Specific Frequencies of 28 Elliptical Galaxies
Kundu, Arunav; Whitmore, Bradley C.
We present an analysis of the globular cluster systems of 28 elliptical galaxies using archival WFPC2 images in the V and I bands. The V-I color distributions of at least 50% of the galaxies appear to be bimodal at the present level of photometric accuracy. We argue that this is indicative of multiple epochs of cluster formation early in the histo…
M33: A Galaxy with No Supermassive Black Hole
Gebhardt, Karl; Richstone, Douglas; Kormendy, John +9 more
Galaxies that contain bulges appear to contain central black holes whose masses correlate with the velocity dispersion of the bulge. We show that no corresponding relationship applies in the pure disk galaxy M33. Three-integral dynamical models fit Hubble Space Telescope WFPC2 photometry and Space Telescope Imaging Spectrograph spectroscopy best i…
Population Gradients in Local Group Dwarf Spheroidal Galaxies
Grebel, Eva K.; Dolphin, Andrew; Holtzman, Jon +7 more
We present a systematic and homogeneous analysis of population gradients for the Local Group dwarf spheroidal galaxies (dSph's) Carina, Sculptor, Sextans, Tucana, and Andromeda I-III, V, and VI. For all of the Milky Way companions studied here, we find significant population gradients. The same is true for the remote dSph Tucana located at the out…