Search Publications
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 …
A Catalog of Bright Star Clusters in the Interacting Galaxy M51
Hwang, Narae; Lee, Myung Gyoon
We present a catalog of star clusters with V F555W < 23 mag detected in the interacting spiral galaxy M51 system based on mosaic images taken with the Hubble Space Telescope Advanced Camera for Surveys by the Hubble Heritage Team. We have selected about 3600 clusters based on their morphological information through visual inspection.…
Very Large Array Limits for Intermediate-Mass Black Holes in Three Globular Clusters
Gebhardt, K.; Goss, W. M.; Bash, F. N. +1 more
The observational evidence for central black holes in globular clusters has been argued extensively, and their existence has important consequences for both the formation and evolution of the cluster. Most of the evidence comes from dynamical arguments, but the interpretation is difficult, given the short relaxation times and old ages of the clust…
Triggered or Self-Regulated Star Formation within Intermediate Redshift Luminous Infrared Galaxies. I. Morphologies and Spectral Energy Distributions
Koo, D. C.; Larkin, J. E.; Wright, S. A. +6 more
As part of the Center for Adaptive Optics (AO) Treasury Survey (CATS) we imaged a set of 15 intermediate redshift (z ~ 0.8) luminous infrared (IR) galaxies (LIRGs) with the Keck Laser Guide Star (LGS) AO facility. These galaxies were selected from the Great Observatories Origins Deep Survey (GOODS) southern field, allowing us to combine the high s…
The Peculiar Globular Cluster System of the s0 Galaxy NGC 7457
Brodie, Jean P.; Strader, Jay; Chomiuk, Laura
We present Hubble Space Telescope photometry and Keck spectroscopy of globular clusters (GCs) in the nearby S0 galaxy NGC 7457. The V - I color-magnitude diagram of GCs lacks the clear bimodality present in most early-type galaxies; there may be a significant population of intermediate-color objects. Of 13 spectroscopically observed GCs, two are u…
Emission-Line Galaxies from the Pears Hubble Ultra Deep Field: a 2d Detection Method and First Results
Hathi, Nimish P.; Koekemoer, Anton M.; Gardner, Jonathan P. +11 more
The Hubble Space Telescope Advanced Camera for Surveys grism Probing Evolution And Reionization Spectroscopically (PEARS) survey provides a large dataset of low-resolution spectra from thousands of galaxies in the GOODS north and south fields. One important subset of objects in these data is emission-line galaxies (ELGs), and we have investigated …
Photometric Oscillations of Low-Luminosity Red Giant Stars
Gilliland, Ronald L.
I present details of the variations of several hundred red giant stars on timescales of a few hours to a few days from Hubble Space Telescope (HST) observations of a low-extinction galactic bulge sample from an intensive seven-day campaign. Variations in the red giants are shown to be a strong function of position within the color-magnitude diagra…
Finding Galaxy Groups in Photometric-Redshift Space: The Probability Friends-of-Friends Algorithm
Yee, H. K. C.; Li, I. H.
We present a structure-finding algorithm designed to identify galaxy groups in photometric-redshift data sets: the probability friends-of-friends (pFoF) algorithm. This algorithm is derived by combining the FoF algorithm in the transverse direction and the photometric-redshift probability densities in the radial dimension. The innovative character…
Deep Advanced Camera for Surveys Imaging in the Globular Cluster NGC 6397: Dynamical Models
Anderson, Jay; Dotter, Aaron; Rich, R. Michael +8 more
We present N-body models to complement deep imaging of the metal-poor core-collapsed cluster NGC 6397 obtained with the Hubble Space Telescope. All simulations include stellar and binary evolution in step with the stellar dynamics and account for the tidal field of the Galaxy. We focus on the results of a simulation that began with 100, 000 object…