Search Publications

Automated Morphological Classification in Deep Hubble Space Telescope UBVI Fields: Rapidly and Passively Evolving Faint Galaxy Populations

Keel, William C.; Driver, Simon P.; Windhorst, Rogier A. +1 more

We analyze deep Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) images in U, B, V, I using artificial neural network (ANN) classifiers, which are based on galaxy surface brightness and light profile (but not on color nor on scale length, rhl). The ANN distinguishes quite well between E/S0, Sabc, and Sd/Irr+M galaxies (M for merging sy…

Interstellar Gas-Phase Abundances and Physical Conditions toward Two Distant High-Latitude Halo Stars

Sembach, Kenneth R.; Savage, Blair D.

Hubble Space Telescope Ultraviolet Spectroscopy of NGC 1741: A Nearby Template for Distant Energetic Starbursts

Leitherer, Claus; Vacca, William D.; Conti, Peter S.

We have obtained a Hubble Space Telescope ultraviolet image and spectrum of the nearby Wolf-Rayet galaxy NGC 1741. The spatial morphology from the Faint Object Camera image is dominated by two main starburst centers, each being about 100 times as luminous as 30 Doradus. Both starburst centers are composed of several intense knots of recent star fo…

Detection of the Tip of the Red Giant Branch in NGC 5128

Soria, Roberto; Casertano, Stefano; Ballester, Gilda E. +14 more

We present a color-magnitude diagram of more than 10,000 stars in the halo of the galaxy NGC 5128 (Centaurus A), based on WFPC2 images through V-band and I-band filters. The position of the red giant branch (RGB) stars is compared with the loci of the red giant branch in six well- studied globular clusters and in the dwarf elliptical galaxy NGC 18…

On the Nature of the Faint Compact Narrow Emission-Line Galaxies: The Half-Light Radius--Velocity Width Diagram

Illingworth, Garth D.; Bershady, Matthew A.; Faber, S. M. +4 more

We present new measurements of emission-line velocity widths for five faint compact narrow emission-line galaxies (CNELGs) with 20.5 <= B <= 21.5 and redshifts z ~ 0.19 to 0.35. The spectra were taken at the Keck telescope using the HIRES spectrograph with a resolution of 8 km s-1 (FWHM). Emission-line profiles are roughly Gaussian with velo…

Ellipticals with Kinematically Distinct Cores: WFPC2 Imaging of Globular Clusters

Franx, Marijn; Illingworth, Garth D.; Forbes, Duncan A. +1 more

New globular clusters may form in the merger of two galaxies. Perhaps the best examples of merger remnants are the set of ellipticals with kinematically distinct cores. Here we present Hubble Space Telescope (HST) Wide Field and Planetary Camera 2 (WFPC2) imaging of 14 kinematically distinct core ellipticals to examine their globular cluster syste…

The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. VI. The Cepheids in NGC 925

Illingworth, Garth D.; Madore, Barry F.; Freedman, Wendy L. +18 more

We report the detection of Cepheid variable stars in the barred spiral galaxy NGC 925, using the Hubble Space Telescope (HST) Wide-Field and Planetary Camera 2 (WFPC2). Twelve V (F555W) and four I (F814W) epochs of cosmic-ray split observations were obtained. Eighty Cepheids were discovered, with periods from 6 to ~80 days. Light curves of the Cep…

The Serendipitous Discovery of a Group or Cluster of Young Galaxies at z2.40 in Deep Hubble Space Telescope WFPC2 Images

Keel, W. C.; Driver, S. P.; Ostrander, E. J. +2 more

We report the serendipitous discovery of a group or cluster of young galaxies at z ~= 2.40 in a 24 orbit Hubble Space Telescope/WFPC2 exposure of the field around the weak radio galaxy 53W002. Potential cluster members were identified on ground-based narrowband redshifted Ly alpha images and confirmed via spectroscopy. In addition to the known wea…

Hubble Space Telescope Observations of the Luminous IRAS Source FSC 10214+4724: A Gravitationally Lensed Infrared Quasar

Hogg, David W.; Eisenhardt, Peter R.; Soifer, B. T. +3 more

With a redshift of 2.3, the IRAS source FSC 10214+4724 is apparently one of the most luminous objects known in the universe. We present an image of FSC 10214+4724 at 0.8 microns obtained with the Hubble Space Telescope (HST) WFPC2 Planetary Camera. The source appears as an unresolved (<0.06") arc 0.7" long, with significant substructure along i…

The Main Sequence and a White Dwarf Sequence in the Globular Cluster NGC 6397

Piotto, Giampaolo; Cool, Adrienne M.; King, Ivan R.

We present a deep color-magnitude diagram of the nearby globular cluster NGC 6397, from V and I images obtained with the Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope (HST). A narrow main sequence extending ∼10 mag below the turnoff is delineated, as well as a white dwarf sequence spanning 3.5 mag. The main sequence has a 1 σ…