Search Publications
The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters without Previous Hubble Space Telescope Photometry
Anderson, Jay; Dotter, Aaron; Sarajedini, Ata +10 more
We present the first results of a large Advanced Camera for Surveys (ACS) survey of Galactic globular clusters. This Hubble Space Telescope (HST) Treasury project is designed to obtain photometry with S/N (signal-to-noise ratio) gtrsim10 for main-sequence stars with masses gtrsim0.2 Modot in a sample of globulars using the ACS Wide Fiel…
The Sloan Digital Sky Survey Quasar Catalog. IV. Fifth Data Release
Castander, Francisco J.; Brandt, W. N.; Shen, Yue +41 more
We present the fourth edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog. The catalog contains 77,429 objects; this is an increase of over 30,000 entries since the previous edition. The catalog consists of the objects in the SDSS Fifth Data Release that have luminosities larger than Mi=-22.0 (in a cosmology with H0…
Hubble Space Telescope Fine Guidance Sensor Parallaxes of Galactic Cepheid Variable Stars: Period-Luminosity Relations
Freedman, Wendy L.; Harrison, Thomas E.; Bean, Jacob L. +6 more
We present new absolute trigonometric parallaxes and relative proper motions for nine Galactic Cepheid variable stars: ell Car, ζ Gem, β Dor, W Sgr, X Sgr, Y Sgr, FF Aql, T Vul, and RT Aur. We obtain these results with astrometric data from Fine Guidance Sensor 1r, a white-light interferometer on the Hubble Space Telescope. We find absolute parall…
The ACS Survey of Galactic Globular Clusters. II. Stellar Evolution Tracks, Isochrones, Luminosity Functions, and Synthetic Horizontal-Branch Models
Anderson, Jay; Dotter, Aaron; Baron, E. +4 more
The ACS Survey of Galactic Globular Clusters, an HST Treasury Project, will deliver high-quality, homogeneous photometry of 65 globular clusters. This paper introduces a new collection of stellar evolution tracks and isochrones suitable for analyzing the ACS survey data. Stellar evolution models were computed at [Fe/H]=-2.5, -2.0, -1.5, -1.0, -0.5…
Optical Spectroscopy and X-Ray Detections of a Sample of Quasars and Active Galactic Nuclei Selected in the Mid-Infrared from Two Spitzer Space Telescope Wide-Area Surveys
Armus, L.; Canalizo, G.; Sajina, A. +5 more
We present optical spectroscopy of a sample of 77 luminous active galactic nuclei (AGNs) and quasars selected on the basis of their mid-infrared colors. Our objects are selected from the Spitzer Extragalactic First Look Survey and the SWIRE XMM-Newton Large-Scale Structure Survey (XMM-LSS) fields, with a typical 24 µm flux density of 5 mJy. …
Preplanetary Nebulae: A Hubble Space Telescope Imaging Survey and a New Morphological Classification System
Sahai, Raghvendra; Sánchez Contreras, Carmen; Morris, Mark +1 more
Using the Hubble Space Telescope (HST), we have carried out a survey of candidate preplanetary nebulae (PPNs). We report here our discoveries of objects having well-resolved geometric structures, and we use the large sample of PPNs now imaged with HST (including previously studied objects in this class) to devise a comprehensive morphological clas…
The Hubble Flow around the Centaurus A/M83 Galaxy Complex
Dolphin, Andrew; Shaya, Edward J.; Tully, R. Brent +8 more
We present Hubble Space Telescope ACS images and color-magnitude diagrams for 24 nearby galaxies in and near the constellation of Centaurus with radial velocities VLG<550 km s-1. Distances are determined based on the luminosities of stars at the tip of the red giant branch that range from 3.0 to 6.5 Mpc. The galaxies are c…
Star Cluster Demographics. I. A General Framework and Application to the Antennae Galaxies
Whitmore, Bradley C.; Fall, S. Michael; Chandar, Rupali
We present a framework for understanding the demographics of star cluster systems and develop a toy model that incorporates a universal initial power-law mass function, selected formation histories, selected disruption laws, and a convolution with common artifacts and selection effects found in observational data. A wide variety of observations ca…
New Distant Companions to Known Nearby Stars. II. Faint Companions of Hipparcos Stars and the Frequency of Wide Binary Systems
Lépine, Sébastien; Bongiorno, Bethany
We perform a search for faint, common proper motion companions of Hipparcos stars using the recently published Lépine-Shara Proper Motion-North catalog of stars with proper motion µ>0.15'' yr-1. Our survey uncovers a total of 521 systems with angular separations 3''<Δθ<1500'', with 15 trip…
A Survey of Local Group Galaxies Currently Forming Stars. II. UBVRI Photometry of Stars in Seven Dwarfs and a Comparison of the Entire Sample
Smith, R. C.; Massey, Philip; Hodge, Paul W. +4 more
We have obtained UBVRI images with the Kitt Peak National Observatory and Cerro Tololo Inter-American Observatory 4 m telescopes and Mosaic cameras of seven dwarfs in (or near) the Local Group, all of which have known evidence of recent star formation: IC 10, NGC 6822, WLM, Sextans B, Sextans A, Pegasus, and Phoenix. We construct color-magnitude d…