Search Publications
Space Velocities of Southern Globular Clusters. II. New Results for 10 Clusters
Girard, Terrence M.; van Altena, William F.; López, Carlos E. +1 more
Absolute proper motions have been measured for 10 clusters, in addition to the sample of five clusters presented in an earlier paper. These newly measured clusters are NGC 1904 (M79), NGC 2298, NGC 4590 (M68), NGC 5139 (omega Cen), NGC 5897, NGC 6093 (M80), NGC 6121 (M4), NGC 6144, NGC 6809 (M55), and NGC 7099 (M30). The correction to absolute pro…
Hubble Space Telescope Observations of Nearby Radio-Loud Early-Type Galaxies
Baum, Stefi A.; de Zeeuw, P. Tim; Verdoes Kleijn, Gijs A. +1 more
We present and analyze Hubble Space Telescope (HST) WFPC2 broad- and narrowband observations of the central regions of 19 nearby radio-loud early-type galaxies. Together with two more galaxies, they form a complete sample of Fanaroff and Riley Type I galaxies. We obtained V- and I-band images and narrowband images centered on the Hα+[N II] emissio…
The Age Difference between the Globular Cluster Subpopulations in NGC 4472
Brodie, Jean P.; Huchra, John P.; Kissler-Patig, Markus +1 more
The age difference between the two main globular cluster subpopulations in the Virgo giant elliptical galaxy NGC 4472 (M49) has been determined using Hubble Space Telescope WFPC2 images in the F555W and F814W filters. Accurate photometry has been obtained for several hundred globular clusters in each of the two main subpopulations, down to more th…
B2045+265: A New Four-Image Gravitational Lens from CLASS
Pearson, T. J.; Bremer, M.; Blandford, R. D. +14 more
We have discovered a new gravitational lens in the Cosmic Lens All-Sky Survey (CLASS). The lens B2045+265 is a four-image system with a maximum separation of 1.9". A fifth radio component is detected, but its radio spectrum and its positional coincidence with infrared emission from the lensing galaxy strongly suggest that it is the radio core of t…
CO Band Head Spectroscopy of IC 342: Mass and Age of the Nuclear Star Cluster
Böker, Torsten; van der Marel, Roeland P.; Vacca, William D.
We have used the NASA Infrared Telescope Facility (IRTF) to observe the nuclear stellar cluster in the nearby, face-on, giant Scd spiral IC 342. From high-resolution (lambda/Deltalambda=21,500) spectra of the ^12CO (2-0) band head at 2.3 mum, we derive a line-of-sight stellar velocity dispersion sigma=(33+/-3) km s^-1. To interpret this observatio…
Stellar Populations at the Center of IC 1613
Cole, Andrew A.; Ballester, Gilda E.; Krist, John E. +18 more
We have observed the center of the Local Group dwarf irregular galaxy IC 1613 with the WFPC2 aboard the Hubble Space Telescope in the F439W, F555W, and F814W filters. We analyze the resulting color-magnitude diagrams (CMDs) using the main-sequence and giant-branch luminosity functions and comparisons with theoretical stellar models to derive a pre…
Speckle Interferometry of New and Problem HIPPARCOS Binaries
Mason, Brian D.; ten Brummelaar, Theo; Barry, Donald J. +7 more
The ESA Hipparcos satellite made measurements of over 12,000 double stars and discovered 3406 new systems. In addition to these, 4706 entries in the Hipparcos Catalogue correspond to double star solutions that did not provide the classical parameters of separation and position angle (rho,theta) but were the so-called problem stars, flagged ``G,'' …
HUBBLE SPACE TELESCOPE Observations of Galactic Globular Cluster Cores. II. NGC 6273 and the Problem of Horizontal-Branch Gaps
Djorgovski, S. G.; Zoccali, M.; Rich, R. M. +4 more
We present observations of the center of the Galactic globular cluster NGC 6273, obtained with the Hubble Space Telescope Wide Field Planetary Camera 2 as part of the snapshot program GO-7470. A BV color-magnitude diagram (CMD) for ~28,000 stars is presented and discussed. The most prominent feature of the CMD, identified for the first time in thi…
Very High Resolution Ultraviolet Spectroscopy of a Chemically Peculiar Star: Results of the chi LUPI Pathfinder Project
Wahlgren, Glenn M.; Proffitt, Charles R.; Brage, Tomas +2 more
We summarize here the results of a major eight-year investigation of the extraordinarily detailed UV spectrum of the sharp-lined, nonmagnetic, main-sequence, chemically peculiar star chi Lupi (B9.5p HgMn + A2 Vm). The UV observations are composed of 345 Å of the spectrum acquired with the Goddard High Resolution Spectrograph (GHRS) on board the Hu…
WFPC2 Observations of Compact Star Cluster Nuclei in Low-Luminosity Spiral Galaxies
Ballester, Gilda E.; Krist, John E.; Crisp, David +15 more
We have used the Wide Field Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope to obtain F450W and F814W (B- and I-band) observations of the compact star cluster nuclei of the nearby, late-type, low-luminosity spiral galaxies NGC 4395, NGC 4242, and ESO 359-029. In addition, we analyze archival WFPC2 observations of the compact star clus…