Search Publications
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…
A Search for Interstellar CH2 toward HD 154368 and ζ Ophiuchi
Smith, Andrew M.; Bruhweiler, Frederick C.; Lyu, Cheng-Hsuan
We have searched for molecular CH2 in the interstellar gas in the line of sight to HD 154368 and ζ Oph to constrain further the gas-phase chemistry of carbon-bearing molecules in the cool, translucent clouds toward these stars. We report tentative detection of CH2 in the interstellar spectra of both stars. In ζ Oph, slight de…
Analysis of Stars Common to the IRAS and Hipparcos Surveys
Knapp, G. R.; Ivezić, Željko; Knauer, Timothy G.
For about 11,000 stars observed in the Hipparcos Survey and detected by IRAS, we calculate bolometric luminosities by integrating their spectral energy distributions from the B band to far-IR wavelengths. We present an analysis of the dependence of dust emission on spectral type and of the correlations between luminosity and dust emission for abou…
Mg II Emission Lines of Hyades F Stars
Robinson, Richard D.; Carpenter, Kenneth G.; Böhm-Vitense, Erika +1 more
With the Hubble Space Telescope (HST) we have observed Hyades F stars, using the Space Telescope Imaging Spectrograph (STIS), in order to get more information about the heating mechanism(s) for the chromospheres and transition layers and their dependence on rotation and age. In this paper we study the Mg II lines at 2800 Å. We include earlier obse…
Shock Wave Emission at Miller's Position 1 in the Cygnus Loop
Blair, William P.; Raymond, J. C.; Li, J. +1 more
We present the far-UV spectrum (900-1800 Å) of the bright filament known as Miller's (1974) position 1 in the Cygnus Loop obtained with the Hopkins Ultraviolet Telescope during the Astro-2 space shuttle mission. Longer wavelength IUE and ground-based spectra of adjoining regions were scaled to produce a combined spectrum ranging from 900 to 7500 Å…
Non-LTE Modeling of Nova Cygni 1992
Baron, E.; Hauschildt, Peter H.; Starrfield, S. +1 more
We present a grid of nova models that have an extremely large number of species treated in non-LTE and apply it to the analysis of an extensive time series of ultraviolet spectroscopic data for Nova Cygni 1992. We use ultraviolet colors to derive the time development of the effective temperature of the expanding atmosphere during the fireball phas…