Search Publications
Yohkoh SXT and SOHO EIT Observations of Sigmoid-to-Arcade Evolution of Structures Associated with Halo Coronal Mass Ejections
Sterling, Alphonse C.; Thompson, Barbara J.; Hudson, Hugh S. +1 more
A subset of the solar-disk counterparts to halo coronal mass ejections (CMEs) displays an evolution in soft X-rays (SXR) that is characterized by a preflare S-shaped structure, dubbed a ``sigmoid,'' which evolves into a postflare cusp or arcade. We examine the morphological properties of the evolution of sigmoids into cusps and arcades for four su…
Helium in near Earth orbit
Usoskin, I.; Laitinen, T.; Valtonen, E. +201 more
The helium spectrum from 0.1 to /100 GeV/nucleon was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at altitudes near 380 km. Above the geomagnetic cutoff the spectrum is parameterized by a power law. Below the geomagnetic cutoff a second helium spectrum was observed. In the second helium spectra over the ener…
Another View of the EIT Wave Phenomenon
Delannée, C.
This paper investigates three different EIT waves. The events occurred on 1997 November 3 at 10:31 UT, on 1998 January 27 at 22:19 UT, and on 1998 June 13 at 15:23 UT and were observed with EIT on board the Solar and Heliospheric Observatory (SOHO) using the 195 Å filter that contains an Fe XII line. The three events show the following similar str…
Photometric Redshifts and Selection of High-Redshift Galaxies in the NTT and Hubble Deep Fields
Fontana, Adriano; Saracco, Paolo; Moorwood, Alan +5 more
We present and compare in this paper new photometric redshift catalogs of the galaxies in three public fields: the NTT Deep Field, the HDF-N, and the HDF-S. In the case of the NTT Deep Field, we present here a new photometric catalog, obtained by combining the existing BVrI and JKs with new deep U observations acquired with NTT-SUSI2, and which in…
The First US Naval Observatory CCD Astrograph Catalog
Zacharias, N.; Urban, S. E.; Wycoff, G. L. +9 more
The USNO CCD Astrograph (UCA) started an astrometric survey in 1998 February at Cerro Tololo, Chile. This first, preliminary catalog (UCAC1) includes data taken up to 1999 November with about 80% of the Southern Hemisphere covered. Observing continues, and full sky coverage is expected by mid-2003 after moving the instrument to a Northern Hemisphe…
A global MHD solar wind model with WKB Alfvén waves: Comparison with Ulysses data
Goldstein, Melvyn L.; Usmanov, Arcadi V.; Besser, Bruno P. +1 more
We use a steady state global axisymmetric MHD model to reproduce quantitatively the Ulysses observations during its first fast latitude traversal in 1994-1995. In particular, we are able to account for the transformation of a surface dipole magnetic field near the Sun into the configuration observed at large heliocentric distances. The MHD equatio…
The structure of the collapsing envelope around the low-mass protostar IRAS 16293-2422
Ceccarelli, C.; Caux, E.; Tielens, A. G. G. M. +4 more
Using H2O, OI and SiO data, we derive the structure of the collapsing envelope around the low-mass protostar IRAS16293-2422 down to r ~ 30 AU. With an accurate model which computes self-consistently the chemical composition, thermal balance and line emission from a collapsing envelope (Ceccarelli et al. 1996), we find that IRAS16293-242…
Multiple shells in IRC+10216: shell properties
Mauron, N.; Huggins, P. J.
We report on the properties of the multiple shells in the circumstellar envelope of IRC+10216, using deep optical imaging, including data from the Hubble Space Telescope. The intensity profiles confirm the presence of thin ( ~ 0farcs5 -3'' ec), limb-brightened shells in the envelope, seen in stellar and ambient Galactic light scattered by dust. Th…
Slow magnetoacoustic waves in coronal loops
Berghmans, D.; Nakariakov, V. M.; Verwichte, E. +1 more
A theoretical model interpreting propagating disturbances of EUV emission intensity, recently observed in coronal loops, is constructed in terms of slow magnetoacoustic waves. The model is one-dimensional and incorporates effects of nonlinearity, dissipation due to finite viscosity and thermal conduction, and gravitational stratification of plasma…
The Evolution of Early-Type Galaxies in Distant Clusters. III. M/LV Ratios in the z=0.33 Cluster CL 1358+62
van Dokkum, Pieter G.; Franx, Marijn; Kelson, Daniel D. +1 more
Internal kinematics, length scales, and surface brightnesses have been determined for a large sample of 53 galaxies in the cluster Cl 1358+62 at z=0.33 from Keck spectroscopy and Hubble Space Telescope WFPC2 imaging over a 1.5 h-1x1.5 h-1 Mpc2 field of view. These data have been used to constrain the evolution of e…