Search Publications
Astrometric Calibration of the Sloan Digital Sky Survey
Hennessy, G. S.; Munn, Jeffrey A.; Ivezić, Željko +4 more
The astrometric calibration of the Sloan Digital Sky Survey is described. For point sources brighter than r~20, the astrometric accuracy is 45 mas rms per coordinate when reduced against the USNO CCD Astrograph Catalog and 75 mas rms when reduced against Tycho-2, with an additional 20-30 mas systematic error in both cases. The rms errors are domin…
A Survey of z>5.7 Quasars in the Sloan Digital Sky Survey. II. Discovery of Three Additional Quasars at z>6
Pentericci, Laura; White, Richard L.; Grebel, Eva K. +28 more
We present the discovery of three new quasars at z>6 in ~ 1300 deg2 of Sloan Digital Sky Survey imaging data, J114816.64+525150.3 (z=6.43), J104845.05+463718.3 (z=6.23), and J163033.90+401209.6 (z=6.05). The first two objects have weak Lyα emission lines; their redshifts are determined from the positions of the Lyman break. They are …
A Direct Measurement of Major Galaxy Mergers at z<~3
Papovich, Casey; Dickinson, Mark; Conselice, Christopher J. +1 more
This paper presents direct evidence for hierarchical galaxy assembly out to redshifts z~3. We identify major mergers using the model-independent CAS (concentration, asymmetry, clumpiness) physical morphological system on galaxies detected, and photometrically selected, in the WFPC2 and NICMOS Hubble Deep Field North. We specifically use the asymme…
HST Photometry of Dwarf Elliptical Galaxies in Coma, and an Explanation for the Alleged Structural Dichotomy between Dwarf and Bright Elliptical Galaxies
Graham, Alister W.; Guzmán, Rafael
As part of a research program exploring how and why dwarf elliptical (dE) galaxies depart from the fundamental plane defined by luminous elliptical (E) galaxies, we have analyzed archival Hubble Space Telescope F606W images of a sample of 18 dE galaxy candidates in the Coma Cluster. We model the full radial extent of their light profiles by simult…
Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I.
Gray, R. O.; Corbally, C. J.; Garrison, R. F. +2 more
We have embarked on a project, under the aegis of the Nearby Stars (NStars)/Space Interferometry Mission Preparatory Science Program, to obtain spectra, spectral types, and, where feasible, basic physical parameters for the 3600 dwarf and giant stars earlier than M0 within 40 pc of the Sun. In this paper, we report on the results of this project f…
Multiplicity of Nearby Free-Floating Ultracool Dwarfs: A Hubble Space Telescope WFPC2 Search for Companions
Basri, Gibor; Bouy, Hervé; Brandner, Wolfgang +3 more
We present Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations of a sample of 134 ultracool objects (spectral types later than M7) coming from the Deep Near Infrared Survey (DENIS), Two Micron All Sky Survey (2MASS), and Sloan Digital Sky Survey (SDSS), with distances estimated to range from 7 to 105 pc. Fifteen new ult…
Ultradeep Near-Infrared ISAAC Observations of the Hubble Deep Field South: Observations, Reduction, Multicolor Catalog, and Photometric Redshifts
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +10 more
We present deep near-infrared (NIR) Js-, H-, and Ks-band ISAAC imaging of the Wide Field Planetary Camera 2 (WFPC2) field of the Hubble Deep Field South (HDF-S). The 2.5‧×2.5‧ high Galactic latitude field was observed with the Very Large Telescope under the best seeing conditions, with integration times amounting to 33.6 hr i…
A New Empirical Model for the Structural Analysis of Early-Type Galaxies, and A Critical Review of the Nuker Model
Graham, Alister W.; Trujillo, I.; Asensio Ramos, A. +1 more
The Nuker law was designed to match the inner few (~3-10) arcseconds of predominantly nearby (<~30 Mpc) early-type galaxy light profiles; it was never intended to describe an entire profile. The Sérsic model, on the other hand, was developed to fit the entire profile; however, because of the presence of partially depleted galaxy cores, the Sérs…
Investigation of 131 Herbig Ae/Be Candidate Stars
Alencar, S. H. P.; Corradi, W. J. B.; Guimarães, M. M. +5 more
We present a new catalog of 108 Herbig Ae/Be candidate stars identified in the Pico dos Dias Survey, together with 19 previously known candidates and four objects selected from the IRAS Faint Source Catalog. These 131 stars were observed with low- and/or medium-resolution spectroscopy, and we complement these data with high-resolution spectra of 3…
Internal Dynamics, Structure, and Formation of Dwarf Elliptical Galaxies. II. Rotating versus Nonrotating Dwarfs
Geha, M.; van der Marel, R. P.; Guhathakurta, P.
We present spatially resolved internal kinematics and stellar chemical abundances for a sample of dwarf elliptical (dE) galaxies in the Virgo Cluster observed with the Keck telescope and Echelle Spectrograph and Imager. In combination with previous measurements, we find that four out of 17 dE's have major-axis rotation velocities consistent with r…