Search Publications
The Solar Corona Above Polar Coronal Holes as Seen by SUMER on SOHO
Wilhelm, Klaus; Marsch, Eckart; Dwivedi, Bhola N. +4 more
In order to address two of the principal scientific objectives of the Solar and Heliospheric Observatory (SOHO), studies of the heating mechanisms of the solar corona and the acceleration processes of the solar wind, we deduce electron temperatures, densities, and ion velocities in plumes and interplume regions of polar coronal holes using ultravi…
The Ultraviolet Spectroscopic Properties of Local Starbursts: Implications at High Redshift
Robert, Carmelle; Heckman, Timothy M.; Leitherer, Claus +2 more
We report the results of a systematic study of the vacuum ultraviolet (λ ~= 1150-2000 Å) spectra of a sample of 45 starburst and related galaxies observed with the IUE satellite. These span broad ranges in metallicity (from 0.02 to 3 times solar), bolometric luminosity (~107-4 × 1011 L⊙), and galaxy properties (e.g…
Luminosity Evolution of Early-Type Galaxies to z = 0.83: Constraints on Formation Epoch and Ω
van Dokkum, Pieter G.; Franx, Marijn; Kelson, Daniel D. +1 more
We present deep Keck telescope spectroscopy of eight galaxies in the luminous X-ray cluster MS 1054-03 at z=0.83. The data are combined with imaging observations from the Hubble Space Telescope (HST). The spectroscopic data are used to measure the internal kinematics of the galaxies, and the HST data are used to measure their structural parameters…
The Angular Clustering of Lyman-Break Galaxies at Redshift Z approximately 3
Giavalisco, Mauro; Dickinson, Mark E.; Pettini, Max +3 more
We have measured the angular correlation function w(θ) for a sample of 871 Lyman-break galaxies (LBGs) in five fields at redshift z ~ 3. Fitting the power law Aw θ-β to a weighted average of w(θ) from the five fields over the range 12" <~ θ <~ 330", we find Aw ~ 2 arcsecβ and β ~ 0.9. The slope is,…
Galactocentric Distance with the Optical Gravitational Lensing Experiment and HIPPARCOS Red Clump Stars
Paczyński, Bohdan; Stanek, Krzysztof Z.
We compare red clump stars with parallaxes known to better than 10% in the Hipparcos catalog and corrected for interstellar extinction with the OGLE red clump stars in Baade's Window, also corrected for interstellar extinction. There are ~600 and ~10,000 such stars in the two data sets, respectively. We find empirically that the average I-band mag…
Energy Distribution of Heating Processes in the Quiet Solar Corona
Krucker, Säm; Benz, Arnold O.
We have determined the variations in the emission measure of the solar corona using EUV Imaging Telescope/Solar and Heliospheric Observatory observations of iron lines in a quiet region of the Sun. The emission measure is found to vary significantly in at least 85% of all the pixels within 42 minutes. The variations are interpreted as heating even…
An Edge-On Circumstellar Disk in the Young Binary System HK Tauri
Ménard, François; Krist, John E.; Stapelfeldt, Karl R. +3 more
Hubble Space Telescope (HST) images of HK Tauri reveal that the companion star in this 2.4" (340 AU) pre-main-sequence binary system is an entirely nebulous object at visual wavelengths. HK Tau/c appears as two elongated reflection nebulosities separated by a dark lane. Near-infrared adaptive optics observations made at the Canada-France-Hawaii Te…
Improved Evidence for a Black Hole in M32 from HST/FOS Spectra. II. Axisymmetric Dynamical Models
van der Marel, Roeland P.; Rix, Hans-Walter; de Zeeuw, P. Tim +1 more
Axisymmetric dynamical models are constructed for the E3 galaxy M32 to interpret high spatial resolution stellar kinematical data obtained with the Hubble Space Telescope (HST). Models are studied with two-integral, f(E, Lz), phase-space distribution functions and with fully general three-integral distribution functions. The latter are …
Multiwavelength Observations of a Dramatic High-Energy Flare in the Blazar 3C 279
Maraschi, L.; Ghisellini, G.; Pian, E. +69 more
The blazar 3C 279, one of the brightest identified extragalactic objects in the γ-ray sky, underwent a large (factor of ~10 in amplitude) flare in γ-rays toward the end of a 3 week pointing by Compton Gamma Ray Observatory (CGRO), in 1996 January-February. The flare peak represents the highest γ-ray intensity ever recorded for this object. During …
Hubble Space Telescope Imaging of the CFRS and LDSS Redshift Surveys. I. Morphological Properties
Tresse, Laurence; Brinchmann, Jarle; Broadhurst, Tom +9 more
We analyze Hubble Space Telescope images of a complete sample of 341 galaxies drawn from the CFRS and LDSS ground-based redshift surveys. In this, the first paper in the series, each galaxy has been morphologically classified according to a scheme similar to that developed for the Medium Deep Survey. We discuss the reproducibility of these classif…