Search Publications
Spitzer Observations of Star Formation in the Extreme Outer Disk of M83 (NGC5236)
Meurer, Gerhardt R.; Calzetti, Daniela; Walter, Fabian +4 more
Spitzer Infrared Array Camera (IRAC) observations of two fields in the extended UV disk (XUV-disk) of M83 have been recently obtained, ~3 R HII away from the center of the galaxy (R HII = 6.6 kpc). Galaxy Evolution Explorer (GALEX) UV images have shown the two fields to host in situ recent star formation. The IRAC images are …
A Multi-Epoch HST Study of the Herbig-Haro Flow from XZ Tauri
Krist, John E.; Hester, J. Jeff; Stapelfeldt, Karl R. +3 more
We present nine epochs of Hubble Space Telescope optical imaging of the bipolar outflow from the pre-main-sequence binary XZ Tauri. Our data monitor the system from 1995 to 2005 and include emission line images of the flow. The northern lobe appears to be a succession of bubbles, the outermost of which expanded ballistically from 1995 to 1999 but …
Surface Brightness Profiles of Composite Images of Compact Galaxies at z ≃ 4-6 in the Hubble Ultra Deep Field
Hathi, N. P.; Keel, W. C.; Jansen, R. A. +4 more
The Hubble Ultra Deep Field (HUDF) contains a significant number of B-, V-, and i'-band dropout objects, many of which were recently confirmed to be young star-forming galaxies at z ≃ 4-6. These galaxies are too faint individually to accurately measure their radial surface-brightness profiles. Their average light profiles are potentially of great …
High Spatial Velocity Features in the Orion Nebula,
O'Dell, C. R.; Henney, W. J.
We have used widely spaced in time Hubble Space Telescope images to determine tangential velocities of features associated with outflows from young stars. These observations were supplemented by ground-based telescope spectroscopy, and from the resultant radial velocities, space velocities were determined for many outflows. Numerous new moving fea…
HD 148937: A Multiwavelength Study of the Third Galactic Member of the Of?p Class
Walborn, Nolan R.; Bond, Howard E.; Nazé, Yaël +3 more
Three Galactic O-type stars belong to the rare class of Of?p objects: HD 108, HD 191612, and HD 148937. The first two stars show a wealth of phenomena, including strong X-ray emission, light variability, and dramatic periodic spectral variability. We present here the first detailed optical and X-ray study of the third Galactic Of?p star, HD 148937…
Old Globular Clusters in Magellanic-Type Dwarf Irregular Galaxies
Georgiev, Iskren Y.; Goudfrooij, Paul; Puzia, Thomas H. +1 more
We have performed a search for old globular clusters (GCs) using archival F606W and F814W Hubble Space Telescope/Advanced Camera for Surveys images of 19 Magellanic-type dwarf Irregular (dIrr) galaxies. Those dIrrs reside in nearby (2-8 Mpc) associations of dwarf galaxies only. All dIrrs have absolute magnitudes fainter than or equal to that of th…
Globular Clusters in the Outer Galactic Halo: AM-1 and Palomar 14
Dotter, Aaron; Sarajedini, Ata; Yang, Soung-Chul
AM-1, at ~120 kpc, and Palomar 14 (Pal 14), at ~70 kpc, are two of the most distant Galactic globular clusters (GCs) known. We present Hubble Space Telescope Wide Field Planetary Camera 2 photometry of AM-1 and Pal 14 that reveals unprecedented depth and detail in the color-magnitude diagrams of these two clusters. Absolute and relative age measur…
A High Resolution View of the Jet Termination Shock in a Hot Spot of the Nearby Radio Galaxy Pictor A: Implications for X-Ray Models of Radio Galaxy Hot Spots
Bondi, M.; Brunetti, G.; Tingay, S. J. +1 more
Images made with the Very Long Baseline Array (VLBA) have resolved the region in a nearby (z = 0.035) radio galaxy, Pictor A, where the relativistic jet that originates at the nucleus terminates in an interaction with the intergalactic medium, a so-called radio galaxy hot spot. This image provides the highest spatial resolution view of such an obj…
Long-Term Variability in the Optical Spectrum of the Seyfert Galaxy NGC 2992
Crenshaw, D. M.; Dietrich, M.; Trippe, M. L. +1 more
New spectra of NGC 2992 from the Cerro Tololo Inter-American Observatory show that this nearby active galactic nucleus changed its type classification to a Seyfert 2 in 2006. It was originally classified as a Seyfert 1.9, and has been previously seen as a Seyfert 1.5 with strong broad Hα emission. A comparison of the reddening and equivalent hydro…
Hubble Space Telescope Spectroscopic Observations of the Narrow-Line Region in Nearby Low-Luminosity Active Galactic Nuclei
Filippenko, Alexei V.; Ho, Luis C.; Shields, Joseph C. +5 more
We present Space Telescope Imaging Spectrograph observations of 14 nearby low-luminosity active galactic nuclei, including 13 LINERs and 1 Seyfert, taken at multiple parallel slit positions centered on the galaxy nuclei and covering the Hα spectral region. For each galaxy, we measure the emission-line velocities, line widths, and strengths to map …