Search Publications
A Test for the Nature of the Type IA Supernova Explosion Mechanism
Pinto, Philip A.; Eastman, Ronald G.; Rogers, Tamara
Currently, popular models for Type Ia supernovae (SNe Ia) fall into two general classes. The first comprises explosions of nearly pure carbon/oxygen (C/O) white dwarfs (WDs) at the Chandrasekhar limit which ignite near their centers. The second consists of lower mass C/O cores which are ignited by the detonation of an accreted surface helium layer…
A Multivariate Analysis of Galaxies in the Hubble Deep Field-North
Thompson, Rodger I.; Corbin, Michael R.; Stobie, Elizabeth +2 more
We use the ultraviolet and optical WFPC2 and near-infrared NICMOS images of the Hubble Deep Field-North to measure and statistically compare an array of parameters for over 250 of the galaxies it contains. These parameters include redshift, rest-frame visible asymmetry and concentration, bolometric luminosity, and extinction-corrected star formati…
Shocking Clouds in the Cygnus Loop
Graham, James R.; Levenson, N. A.
With Hubble Space Telescope Wide-Field Planetary Camera 2 observations of the Cygnus Loop supernova remnant, we examine the interaction of an interstellar cloud with the blast wave on physical scales of 1015 cm. The shock front is distorted, revealing both edge-on and face-on views of filaments and diffuse emission, similar to those obs…
Far-Ultraviolet Spectra of B Stars near the Ecliptic
Drake, Jeremy J.; Bowyer, Stuart; Edelstein, Jerry +7 more
Spectra of B stars in the wavelength range of 911-1100 Å have been obtained with the Espectrógrafo Ultravioleta de Radiación Difusa (EURD) spectrograph on board the Spanish satellite MINISAT-01 with ~5 Å spectral resolution. International Ultraviolet Explorer (IUE) spectra of the same stars have been used to normalize Kurucz models to the distance…
Atomic Physics with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. V. Oscillator Strengths for Neutral Carbon Lines below 1200 Å
Federman, S. R.; Zsargó, J.
We analyzed high-resolution spectra of interstellar C I absorption toward λ Ori, 1 Sco, and δ Sco that were obtained with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. Several multiplets were detected within the wavelength interval 1150-1200 Å, where most C I lines have ill-defined oscillator strength; multiplets at longe…
Eclipsing Broad Emission Lines in Hercules X-1: Evidence for a Disk Wind?
Chiang, James
We present disk wind model calculations for the broad emission lines seen in the ultraviolet spectra of the X-ray binary Hercules X-1. Recent HST/STIS observations of these lines suggest that they are kinematically linked to the orbital motion of the neutron star and exhibit a redshifted to blueshifted evolution of the line shape during the progre…
Solar Origin of a Series of Well-collimated Electron Events
Pick, Monique; Maia, Dalmiro; Hawkins, S. Edward, III +1 more
We investigate the solar origin and propagation of a series of well-collimated energetic electron events on 1997 November 28, measured in situ by the Electron, Proton, and Alpha Monitor (EPAM) experiment on the Advanced Composition Explorer (ACE) spacecraft. EPAM measures electrons in the energy range from 40 to 300 keV over a wide range of look d…
The Cuspy Liner Nucleus of the S0/a Galaxy NGC 2681
Cappellari, Michele; Renzini, Alvio; Greggio, Laura +3 more
The nucleus of the bulge-dominated, multiply barred S0/a galaxy NGC 2681 is studied in detail using the high-resolution Hubble Space Telescope Faint Object Camera (FOC), Near-Infrared Camera and Multiobject Spectrometer (NICMOS) imaging, and the Faint Object Spectrograph (FOS). The ionized gas central velocity dispersion is found to increase by a …
Millimeter Continuum Image of the Circumstellar Disk around the Young Star Haro 6-5B
Tamura, Motohide; Kawabe, Ryohei; Momose, Munetake +4 more
Aperture synthesis observations of dust continuum emission at 2 mm from the class I object Haro 6-5B, made with the Nobeyama Millimeter Array, are presented. A disklike structure that coincides with the dark lane in the visible and near-infrared images is clearly resolved with a small synthesized beam of 1.33"×1.21" with its position angle (P.A.) …
Energy Distribution of Solar Oscillation Modes Inferred from Space-based Measurements
Korzennik, S. G.; Rabello-Soares, M. C.; Tarbell, T. D. +3 more
We have measured the energy distribution of solar p- and f-mode oscillations of angular degree and temporal frequency in the range 100<l<800 and 2<ν(mHz)<4 using helioseismology data from the Solar Oscillations Investigation-Michelson Doppler Imager instrument on the Solar and Heliospheric Observatory satellite. At temporal frequency ν…