Search Publications
The Three-Dimensional Dynamic Structure of the Inner Orion Nebula
Abel, N. P.; O'Dell, C. R.; Henney, W. J. +2 more
The three-dimensional structure of the brightest part of the Orion Nebula is assessed in the light of published and newly established data. We find that the widely accepted model of a concave blister of ionized material needs to be altered in the southwest direction from the Trapezium, where we find that the Orion-S feature is a separate cloud of …
The Globular Cluster Systems in the Coma Ellipticals. IV: WFPC2 Photometry for Five Giant Ellipticals
Kavelaars, J. J.; Harris, William E.; Pritchet, Christopher J. +2 more
We analyze photometric data in V and I for the globular cluster (GC) systems in five of the giant ellipticals in the Coma Cluster: NGC 4874, 4881, 4889, 4926, and IC 4051. All of the raw data, from the Hubble Space Telescope Wide Field Planetary Camera 2 Archive, are analyzed in a homogeneous way so that their five cluster systems can be strictly …
Astrometry with the Hubble Space Telescope: Trigonometric Parallaxes of Planetary Nebula Nuclei NGC 6853, NGC 7293, Abell 31, and DeHt 5
Bond, Howard E.; Harrison, Thomas E.; Ciardullo, Robin +6 more
We present absolute parallaxes and relative proper motions for the central stars of the planetary nebulae NGC 6853 (The Dumbbell), NGC 7293 (The Helix), Abell 31, and DeHt 5. This paper details our reduction and analysis using DeHt 5 as an example. We obtain these planetary nebula nuclei (PNNi) parallaxes with astrometric data from Fine Guidance S…
Mass-to-Light Ratios for M31 Globular Clusters: Age Dating and a Surprising Metallicity Trend
Brodie, Jean P.; Huchra, John P.; Strader, Jay +2 more
We have obtained velocity dispersions from Keck high-resolution integrated spectroscopy of 10 M31 globular clusters (GCs), including three candidate intermediate-age GCs. We show that these candidates have the same V-band mass-to-light (M/LV ) ratios as the other GCs, implying that they are likely to be old. We also find a trend of deri…
Structural Parameters of Seven Small Magellanic Cloud Intermediate-Age and Old Star Clusters
Grebel, Eva K.; Gallagher, John S., III; Sabbi, Elena +9 more
We present structural parameters for the seven intermediate-age and old star clusters NGC 121, Lindsay 1, Kron 3, NGC 339, NGC 416, Lindsay 38, and NGC 419 in the Small Magellanic Cloud (SMC). We fit King profiles and Elson, Fall, and Freeman profiles to both surface-brightness and star-count data taken with the Advanced Camera for Surveys aboard …
An Extended Dust Disk in a Spiral Galaxy: An Occulting Galaxy Pair in the ACS Nearby Galaxy Survey Treasury
Dalcanton, J. J.; Holwerda, B. W.; Keel, W. C. +2 more
We present an analysis of an occulting galaxy pair, serendipitously discovered in the ACS Nearby Galaxy Survey Treasury observations of NGC 253 taken with the Hubble Space Telescope's (HST) Advanced Camera for Surveys in F475W, F606W, and F814W (SDSS - g, broad V, and I). The foreground disk system (at z <= 0.06) shows a dusty disk much more ex…
Resolving the Stellar Outskirts of M81: Evidence for a Faint, Extended Structural Component
Jablonka, P.; Ferguson, A. M. N.; Barker, M. K. +2 more
We present a wide field census of resolved stellar populations in the northern half of M81, conducted with Suprime-Cam on the 8 m Subaru telescope and covering an area ~0.3 deg2. The resulting color-magnitude diagram reaches over one magnitude below the red giant branch (RGB) tip, allowing a detailed comparison between the young and old…
High-Resolution X-Ray Spectroscopy of the Evolving Shock in the 2006 Outburst of RS Ophiuchi
Ness, J. -U.; Eyres, S. P. S.; Evans, A. +9 more
The evolution of the 2006 outburst of the recurrent nova RS Ophiuchi was followed with 12 X-ray grating observations with Chandra and XMM-Newton. We present detailed spectral analyses using two independent approaches. From the best data set, taken on day 13.8 after outburst, we reconstruct the temperature distribution and derive elemental abundanc…
Scl-dE1 GC1: An Extended Globular Cluster in a Low-Luminosity Dwarf Elliptical Galaxy
Rejkuba, M.; Da Costa, G. S.; Grebel, E. K. +2 more
We report the discovery from Hubble Space Telescope/ACS images of an extended globular cluster, denoted by Scl-dE1 GC1, in the Sculptor Group dwarf Elliptical galaxy Scl-dE1 (Sc22). The distance of the dE is determined as 4.3 ± 0.25 Mpc from the I magnitude of the tip of the red giant branch in the color-magnitude diagram. At this distance the hal…
RR Lyrae Variables in Two Fields in the Spheroid of M31
Lauer, Tod R.; Dressler, Alan; Grillmair, Carl +5 more
We present Hubble Space Telescope observations taken with the Advanced Camera for Surveys Wide Field Channel of two fields near M32—between 4 and 6 kpc from the center of M31. The data cover a time baseline sufficient for the identification and characterization of 681 RR Lyrae variables of which 555 are ab-type and 126 are c-type. The mean magnitu…