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Variations of Saturn's radio rotation period measured at kilometer wavelengths
Lecacheux, Alain; Galopeau, Patrick H. M.
The Unified Radio and Plasma Wave (URAP) experiment on the interplanetary spacecraft Ulysses is able to detect the Saturnian kilometric radiation (SKR) thanks to the high sensitivity of the receiver and in spite of the remoteness of the planet (8-13 AU). Our knowledge about Saturn comes essentially from the observations by the two Voyager spacecra…
The Local Lyα Forest. II. Distribution of H I Absorbers,Doppler Widths, and Baryon Content
Shull, J. Michael; Stocke, John T.; Penton, Steven V.
In Paper I of this series we described observations of 15 extragalactic targets taken with the Hubble Space Telescope+GHRS+G160M grating for studies of the low-z Lyα forest. We reported the detection of 111 Lyα absorbers at significance level (SL) >=3 σ, 81 with SL>=4 σ, in the redshift range 0.002<z<0.069, over a total path length cΔz…
The Origin of Runaway Stars
de Bruijne, J. H. J.; de Zeeuw, P. T.; Hoogerwerf, R.
Milliarcsecond astrometry provided by Hipparcos and by radio observations makes it possible to retrace the orbits of some of the nearest runaway stars and pulsars to determine their site of origin. The orbits of the runaways AE Aurigae and µ Columbae and of the eccentric binary ι Orionis intersected each other ~2.5 Myr ago in the nascent Tra…
An IUE Atlas of Pre-Main-Sequence Stars. II. Far-Ultraviolet Accretion Diagnostics in T Tauri Stars
Valenti, Jeff A.; Johns-Krull, Christopher M.; Linsky, Jeffrey L.
We use our ultraviolet (UV) atlas of pre-main-sequence stars constructed from all useful, short-wavelength, low-resolution spectra in the International Ultraviolet Explorer (IUE) satellite Final Archive to analyze the short-wavelength UV properties of 49 T Tauri stars (TTSs). We compare the line and continuum fluxes in these TTSs with each other a…
The Three-dimensional Structure of the Warm Local Interstellar Medium. II. The Colorado Model of the Local Interstellar Cloud
Redfield, Seth; Linsky, Jeffrey L.
In this second paper in a series on the structure of the local interstellar medium (LISM), we construct a three-dimensional model of the local interstellar cloud (LIC) based on Hubble Space Telescope (HST), Extreme Ultraviolet Explorer (EUVE), and ground-based Ca II spectra. Starting with hydrogen column densities derived from deuterium column den…
Time-Distance Helioseismology with f Modes as a Method for Measurement of Near-Surface Flows
Duvall, T. L., Jr.; Gizon, L.
Travel times measured for the f mode have been used to study flows near the solar surface in conjunction with simultaneous measurements of the magnetic field. Previous flow measurements of Doppler surface rotation, small magnetic feature rotation, supergranular pattern rotation, and surface meridional circulation have been confirmed. In addition, …
Observations of Irradiance Variations
Fröhlich, Claus
Since November 1978 a complete set of total solar irradiance (TSI) measurements from space is available, yielding a time series of 21 years. From measurements made by different space radiometers (HF on NIMBUS-7, ACRIM I on SMM, ACRIM II on UARS and VIRGO on SOHO) a composite record of TSI can be compiled. The corrections which are needed for each …
Supra-arcade Downflows in Long-Duration Solar Flare Events
McKenzie, D. E.
This report seeks to introduce the reader to a set of observations made during the decay phase of long-duration event (LDE) flares on the Sun. In a number of events, the soft X-ray images from Yohkoh SXT indicate a downward-directed flow field in the region immediately above the flare arcade. The prototypical event is the M5 flare of 20 January 19…
Mass-radius relations for white dwarf stars of different internal compositions
Althaus, L. G.; Panei, J. A.; Benvenuto, O. G.
The purpose of this work is to present accurate and detailed mass-radius relations for white dwarf (WD) models with helium, carbon, oxygen, silicon and iron cores, and with and without a hydrogen envelope, by using a fully updated stellar evolutionary code. We considered masses from 0.15 Msun to 0.5 Msun for the case of hel…
Membership and Multiplicity among Very Low Mass Stars and Brown Dwarfs in the Pleiades Cluster
Zapatero Osorio, M. R.; Luhman, K. L.; Martín, E. L. +5 more
We present near-infrared photometry and optical spectroscopy of very low mass stars and brown dwarf candidates in the Pleiades open cluster. The membership status of these objects is assessed using color-magnitude diagrams, lithium and spectral types. Eight objects out of 45 appear to be nonmembers. A search for companions among 34 very low mass P…