Search Publications
A New Nonparametric Approach to Galaxy Morphological Classification
Lotz, Jennifer M.; Primack, Joel; Madau, Piero
We present two new nonparametric methods for quantifying galaxy morphology: the relative distribution of the galaxy pixel flux values (the Gini coefficient or G) and the second-order moment of the brightest 20% of the galaxy's flux (M20). We test the robustness of G and M20 to decreasing signal-to-noise ratio (S/N) and spatia…
A Catalog of Neighboring Galaxies
Karachentsev, Igor D.; Makarov, Dmitry I.; Karachentseva, Valentina E. +1 more
We present an all-sky catalog of 451 nearby galaxies, each having an individual distance estimate D<~10 Mpc or a radial velocity VLG<550 km s-1. The catalog contains data on basic optical and H I properties of the galaxies, in particular, their diameters, absolute magnitudes, morphological types, circumnuclear region ty…
The Second US Naval Observatory CCD Astrograph Catalog (UCAC2)
Zacharias, N.; Urban, S. E.; Wycoff, G. L. +4 more
The second US Naval Observatory (USNO) CCD Astrograph Catalog, UCAC2 was released in 2003 July. Positions and proper motions for 48,330,571 sources (mostly stars) are available on 3 CDs, supplemented with Two Micron All Sky Survey photometry for 99.5% of the sources. The catalog covers the sky area from -90° to +40° declination, going up to +52° i…
The Size Distribution of Trans-Neptunian Bodies
Brown, M. E.; Bernstein, G. M.; Trilling, D. E. +3 more
We search 0.02 deg2 of the invariable plane for trans-Neptunian objects (TNOs) 25 AU or more distant using the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope. With 22 ks per pointing, the search is more than 50% complete for m606W<=29.2. Three new objects are discovered, the faintest with mean magnitud…
The Mass Accretion Rates of Intermediate-Mass T Tauri Stars
Gordon, Karl D.; Hartmann, Lee; Calvet, Nuria +4 more
We present Hubble Space Telescope ultraviolet spectra and supporting ground-based data for a sample of nine intermediate-mass T Tauri stars (IMTTSs; 1.5-4 Msolar). The targets belong to three star-forming regions: T Tau, SU Aur, and RY Tau in the Taurus clouds; EZ Ori, P2441, and V1044 Ori in the Ori OB1c association surrounding the Ori…
Preliminary Parallaxes of 40 L and T Dwarfs from the US Naval Observatory Infrared Astrometry Program
Brinkmann, J.; Kirkpatrick, J. Davy; Fan, X. +12 more
We present preliminary trigonometric parallaxes and proper motions for 22 L dwarfs and 18 T dwarfs measured using the ASTROCAM infrared imager on the US Naval Observatory (USNO) 1.55 m Strand Astrometric Reflector. The results presented here are based on observations obtained between 2000 September and 2002 November; about half of the objects have…
A Deep Wide-Field, Optical, and Near-Infrared Catalog of a Large Area around the Hubble Deep Field North
Stern, D.; Dickinson, M.; Giavalisco, M. +10 more
We have conducted a deep multicolor imaging survey of 0.2 deg2 centered on the Hubble Deep Field North (HDF-N). We shall refer to this region as the Hawaii HDF-N. Deep data were collected in U, B, V, R, I, and z' bands over the central 0.2 deg2 and in HK' over a smaller region covering the Chandra Deep Field North. The data w…
The Fall of Active Galactic Nuclei and the Rise of Star-forming Galaxies: A Close Look at the Chandra Deep Field X-Ray Number Counts
Hornschemeier, A. E.; Alexander, D. M.; Treister, E. +4 more
We investigate the X-ray number counts in the 1-2 Ms Chandra Deep Fields (CDFs) to determine the contributions of faint X-ray source populations to the extragalactic X-ray background (XRB). X-ray sources were separated into active galactic nuclei (AGNs), star-forming galaxies, and Galactic stars primarily on the basis of their X-ray-to-optical flu…
The Team Keck Treasury Redshift Survey of the GOODS-North Field
Davis, Marc; Capak, Peter; Faber, S. M. +19 more
We report the results of an extensive imaging and spectroscopic survey in the Great Observatories Origins Deep Survey (GOODS)-North field completed using DEIMOS on the Keck II telescope. Observations of 2018 targets in a magnitude-limited sample of 2911 objects to RAB=24.4 yield secure redshifts for a sample of 1440 galaxies and active …
Evidence for a New Elliptical-Galaxy Paradigm: Sérsic and Core Galaxies
Graham, Alister W.; Trujillo, I.; Asensio Ramos, A. +1 more
We fitted the surface-brightness profiles of 21 elliptical galaxies using both the Sérsic function and a new empirical model that combines an inner power law with an outer Sérsic function. The profiles are combinations of deconvolved Hubble Space Telescope (HST) profiles from the literature and ellipse fits to the full WFPC2 mosaic images and thus…