Search Publications
Motion of the footpoints of heliospheric magnetic field lines at the Sun: Implications for recurrent energetic particle events at high heliographic latitudes
Fisk, L. A.
The interplay between the differential rotation of the footpoints of heliospheric magnetic field lines in the photosphere and the subsequent nonradial expansion of these same field lines with the solar wind from rigidly rotating coronal holes can result in extensive excursions of heliospheric magnetic field lines with heliographic latitude. Thus m…
Mineralogy of oxygen-rich dust shells.
Lutz, D.; Genzel, R.; Heras, A. M. +34 more
Spectra taken with the Short Wavelength Spectrometer on board of the Infrared Space Observatory of dust shells around evolved oxygen-rich stars reveal the presence of several emission features at wavelengths between 20 and 45µm. These features have a range of widths and strengths, but are all narrow compared to the well-known amorphous silic…
A Morphological Catalog of Galaxies in the Hubble deep Field
Ellis, Richard S.; Abraham, Roberto G.; van den Bergh, Sidney +3 more
We present a catalog of morphological and color data for galaxies with 21 <I_814_ < 25 mag in the Hubble Deep Field (Williams et al. 1996). Galaxies have been inspected and (when possible) independently visually classified on the MDS and DDO systems. Measurements of central concentration and asymmetry are also included in the catalog. The fr…
The Abundance of Interstellar Carbon
Savage, Blair D.; Meyer, David M.; Jura, M. +1 more
We present an analysis of the abundance of interstellar carbon toward six stars within 600 pc of the Sun based upon high signal-to-noise (S/N ≃ 400-600) data of the weak intersystem line C II] λ2325 Å obtained with the Goddard High Resolution Spectrograph aboard the Hubble Space Telescope. We find that the measured gas-phase C/H shows no dependenc…
Hubble Space Telescope Imaging of Star-forming Galaxies at Redshifts Z > 3
Giavalisco, Mauro; Steidel, Charles C.; Macchetto, F. Duccio
We present Hubble Space Telescope images of star-forming galaxies at redshifts z > 3. These galaxies have been selected using ground-based images and color criteria sensitive to the presence of a Lyman discontinuity in the otherwise flat (in fnu_ units) UV spectral energy distribution of unreddened star formation. The spectroscopic c…
Water Vapor Saturation at Low Altitudes around Mars Aphelion: A Key to Mars Climate?
Clancy, R. T.; Wolff, M. J.; Grossman, A. W. +6 more
The combined analysis of microwave temperature and water profiling of the Mars atmosphere indicates that low- to mid-latitude water vapor saturation typically occurs at much lower altitudes (below 10 km) during northern spring/summer than observed during this Mars aphelion season in the dusty, warm period of Viking observations (above 25 km). Temp…
The Centers of Early-Type Galaxies With HST. III. Non-Parametric Recovery of Stellar Luminosity Distribution
Gebhardt, Karl; Richstone, Douglas; Kormendy, John +7 more
We have non-parametrically determined the luminosity density profiles and their logarithmic slopes for 42 early-type galaxies observed with HST. Assuming that the isodensity contours are spheroidal, then the luminosity density is uniquely determined from the surface brightness data through the Abel equation. For nearly all the galaxies in our samp…
Evidence for a Massive Black Hole in the Active Galaxy NGC 4261 from Hubble Space Telescope Images and Spectra
Ferrarese, Laura; Ford, Holland C.; Jaffe, Walter
We present HST/WFPC2 V, R, and I images and Hubble Space Telescope/FOS spectra of the active galaxy NGC 4261. The galaxy hosts a nuclear disk of dust (see papers by Jaffe et al.), roughly perpendicular to the radio jet. The images presented here show evidence of a spiral-like structure in the disk that likely provides the means by which angular mo…
SWS observations of the Galactic center.
Lutz, D.; Genzel, R.; Sturm, E. +11 more
We present a 2.4-45µm spectrum of the center of our Galaxy obtained with the Short Wavelength Spectrometer (SWS) on board ISO. The wide range of ionic fine structure lines observed yields an average effective temperature for the ionizing stars of 35000K, with a small contribution of significantly hotter stars, consistent with ageing of an ac…
The α Centauri line of sight: D/H ratio, physical properties of local interstellar gas, and measurement of heated hydrogen (the "hydrogen wall") near the heliopause.
Wood, Brian E.; Linsky, Jeffrey L.
The authors analyze high resolution spectra of the nearby (1.34 pc) stars α Cen A (G2 V) and α Cen B (K1 V), which were obtained with the GHRS on the HST. The observations consist of echelle spectra of the Mg II 2800 Å and Fe II 2599 Å resonance lines and the Lyman-α lines of hydrogen and deuterium. The interstellar gas has a velocity of v = -18.0…