Search Publications
The Spatial Distribution of the Far-Infrared Emission in NGC 253
Pérez García, A. M.; Acosta-Pulido, J. A.; Melo, V. P. +2 more
We study the far-infrared emission properties of the nearby starburst galaxy NGC 253 based on IRAS maps and an ISOPHOT map at 180 µm. Based on the analysis of the light profiles, we have been able to identify three main structural components: an unresolved nuclear component, an exponential disk, and a kiloparsec-scale bar. In addition, we al…
Multiple Light Echoes from SN 1993J
Crotts, Arlin P. S.; Sugerman, Ben E. K.
Using the technique of point-spread function-matched image subtraction, we have analyzed archival Hubble Space Telescope (HST) Wide Field Planetary Camera 2 data to reveal details of at least two light echo structures, including some unknown before now, around SN 1993J in the galaxy M81. In particular, we see one partial sheet of material 81 pc in…
Subarcsecond Mid-Infrared Imaging of Two Post-Asymptotic Giant Branch 21 Micron Sources
Volk, Kevin; Kwok, Sun; Hrivnak, Bruce J.
High-resolution (FWHM 0.4") mid-infrared images have been obtained for two proto-planetary nebulae possessing the 21 µm emission feature (IRAS 07134+1005 and Z02229+6208). Images through five filters were obtained, covering the 11.3 and 21 µm emission features as well as the adjacent dust continuum. The images of IRAS 07134+1005 show a…
The Effects of Dust in Simple Environments: Large Magellanic Cloud H II Regions
Bell, Eric F.; Gordon, Karl D.; Zaritsky, Dennis +1 more
We investigate the effects of dust on Large Magellanic Cloud (LMC) H II region spectral energy distributions using arcminute-resolution far-ultraviolet (FUV), Hα, far-infrared (FIR), and radio images. Widely used indicators of the amount of light lost to dust (attenuation) at Hα and in the FUV correlate with each other, although often with substan…
The Spectral Energy Distribution and Mass-Loss Rate of the A-Type Supergiant Deneb
Howarth, I. D.; Hauschildt, P. H.; Baron, E. +5 more
A stellar wind module has been developed for the PHOENIX stellar atmosphere code for the purpose of computing non-LTE, line-blanketed, expanding atmospheric structures and detailed synthetic spectra of hot luminous stars with winds. We apply the code to observations of Deneb, for which we report the first positive detections of millimeter and cent…
Uncertainties in Dielectronic Recombination Rate Coefficients: Effects on Solar and Stellar Upper Atmosphere Abundance Determinations
Laming, J. Martin; Savin, Daniel Wolf
We have investigated how the relative elemental abundances inferred from the solar upper atmosphere are affected by uncertainties in the dielectronic recombination (DR) rate coefficients used to analyze the spectra. We find that the inferred relative abundances can be up to a factor of ~5 smaller or ~1.6 larger than those inferred using the curren…
Large-Scale Solar Coronal Structures in Soft X-Rays and Their Relationship to the Magnetic Flux
Kosovichev, A. G.; Benevolenskaya, E. E.; Scherrer, P. H. +2 more
We have investigated the relationship between magnetic activity and coronal structures using soft X-ray data from the Yohkoh soft X-ray telescope and magnetic field data from the Kitt Peak Solar Observatory for the period of 1991-2001 and EUV data from the Solar and Heliospheric Observatory EUV Imaging Telescope for 1996-2001. The data are reduced…
Comparative Analysis of GALLEX-GNO Solar Neutrino Data and SOHO/MDI Helioseismology Data: Further Evidence for Rotational Modulation of the Solar Neutrino Flux
Sturrock, Peter A.; Weber, Mark A.
Recent histogram analysis of GALLEX-GNO and SAGE data indicates that the solar neutrino flux, in the energy range of gallium experiments, varies on a timescale of weeks. Such variability could be caused by modulation of the neutrino flux by an inhomogeneous magnetic field in the solar interior if neutrinos have a nonzero magnetic moment. We may th…
Abundances and Physical Conditions in the Interstellar Gas toward HD 192639
York, D. G.; Sonnentrucker, P.; Welty, D. E. +2 more
We present a study of the abundances and physical conditions in the interstellar gas toward the heavily reddened star HD 192639 [E(B-V)=0.64], based on analysis of Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra covering the range from 912 to 1361 Å. This work constit…
Resolving the Buried Starburst in Arp 299
Charmandaris, V.; Stacey, G. J.; Gull, G.
We present new 37.7 µm far-infrared imaging of the infrared luminous (LIR~5.16×1011Lsolar) interacting galaxy Arp 299 (= IC 694 + NGC 3690). We show that the 38 µm flux, like the 60 and 100 µm emission, traces the luminosity of star forming galaxies but at considerably higher spatial resolution. O…