Search Publications
A NICMOS Survey of Early-Type Galaxy Centers: The Relation Between Core Properties, Gas and Dust Content, and Environment
Bower, Gary A.; Quillen, A. C.; Stritzinger, M.
We present a NICMOS 1.6 µm imaging isophotal study of 27 early-type galaxies. Core galaxies have reduced ellipticity and boxiness near and within their core or break radius. This supports a core formation mechanism that mixes or scatters stars such as scattering caused by a binary black hole. We find the same trends between central surface b…
The Hubble Space Telescope Quasar Absorption Line Key Project. XV. Milky Way Absorption Lines
Schneider, Donald P.; Savage, Blair D.; Sargent, W. L. W. +10 more
This paper presents the results of an analysis of the Milky Way absorption lines found in the Hubble Space Telescope (HST) Quasar Absorption Line Key Project database for 83 QSOs observed with the Faint Object Spectrograph G190H and G270H gratings, of which 16 QSOs are also observed with the G130H grating. The HST Key Project observations are supp…
The Narrow-Line Region in the Seyfert 2 Galaxy NGC 3393
Ferland, G. J.; Wilson, Andrew S.; Netzer, Hagai +2 more
The narrow-line region (NLR) of the Seyfert 2 galaxy NGC 3393 is dominated by a symmetric structure which appears as S-shaped arms in Hubble Space Telescope (HST) images. These arms, which occupy the central few arcseconds of the nucleus, border a linear, triple-lobed radio source. We use HST imaging and spectra, ground-based optical images, long-…
Magellanic Cloud-Type Interstellar Dust along Low-Density Sight Lines in the Galaxy
Gordon, Karl D.; Clayton, Geoffrey C.; Wolff, Michael J.
We have studied the UV extinction properties along 30 Galactic sight lines using data from the International Ultraviolet Explorer archive that have never been previously examined. These distant (d>1 kpc) sight lines were selected to investigate the distribution and physical conditions of gas located in low-density regions of the Galactic disk a…
Calibrating Array Detectors
Fixsen, D. J.; Arendt, R. G.; Moseley, S. H.
The development of sensitive large-format imaging arrays for the infrared promises to provide revolutionary capabilities for space astronomy. For example, the Infrared Array Camera (IRAC) on SIRTF will use four 256×256 arrays to provide background limited high spatial resolution images of the sky in the 3 to 8 µm spectral region. In order to…
Nuclear Gas and Dust Disks in Nearby 3CR Elliptical Galaxies
Baum, Stefi A.; Sparks, William B.; Turner, Neal J. +1 more
Using WFPC2 V, R, I, and Hα+[N II] images, we examine the morphologies, environments, colors, and line emission of dust and gas disks located in the cores of seven low-redshift elliptical galaxies hosting 3C radio sources: NGC 383 (3C 31)/NGC 382, NGC 547 (3C 40), NGC 3862 (3C 264), NGC 4261 (3C 270), NGC 5532 (3C 296), NGC 7720 (3C 465)/NGC 7720A…
Theoretical Oscillator Strengths inPr III and Application to Some CP Stars
Quinet, P.; Frémat, Y.; Palmeri, P. +2 more
A set of transition probabilities is obtained for the first time for many transitions of Pr III of astrophysical interest. A relativistic Hartree-Fock method, combined with a least-squares fitting of the available experimental levels, including a large number of newly determined values, has been used for the calculations in which configuration int…
Charged-Particle Resonance Conditions and Transport Coefficients in Slab-Mode Waves
Vainio, R.
Transport of charged particles in cold plasma is considered. The full dispersion relation for slab-mode waves is employed, and the quasi-linear particle scattering is discussed. Previous results of the dispersive-wave model on the ion mean free path are recalled and further developed. For small cross-helicities, the model predicts ion mean free pa…
The Structure of Wolf-Rayet Winds. II. Observations of Ionization Stratification in the WN Subtype
Morris, P.; Herald, J. E.; Schulte-Ladbeck, R. E. +1 more
Motivated by the question of the importance of ionization stratification in solving the ``momentum problem'' of Wolf-Rayet stellar winds, we have chosen a sample of 14 WN stars for a systematic study. We performed measurements of the emission line widths on ultraviolet, optical, and infrared spectra to obtain data spanning a large range of ionizat…
Structural Characteristics of Faint Galaxies Serendipitously Discovered with the Hubble Space Telescope WFPC2
Impey, C. D.; Bothun, G. D.; O'Neil, Karen
Utilizing the F814W and F300W filters, Hubble Space Telescope Wide Field Planetary Camera-2 (WFPC2) images were taken of four low surface brightness galaxies in the direction of the Virgo Cluster--V7L3, V2L8, V1L4, and Malin 1. The high resolution of the WFPC2 combined with the extremely diffuse nature of the four galaxies makes them essentially t…