Science Archives Publication System

Evidence for Strong and Weak Turbulence Processes in the Source Region of a Local Type III Radio Burst

DOI: 10.1086/305526 Bibcode: 1998ApJ...498..465T

MacDowall, R. J.; Thejappa, G.

We present the Ulysses Unified Radio and Plasma Wave Experiment (URAP) observations of a local type III radio burst and the associated plasma wave activity generated in the vicinity of the spacecraft. These observations represent the first clear evidence of (1) the occurrence of ion-acoustic waves as well as whistlers in close association with Lan…

1998 • The Astrophysical Journal

Ulysses 49

The Hubble Deep Field and the disappearing dwarf galaxies

DOI: 10.1046/j.1365-8711.1998.01371.x Bibcode: 1998MNRAS.296..585F

Ferguson, Henry C.; Babul, Arif

Several independent lines of reasoning, both theoretical and observational, suggest that the very faint (B>~24) galaxies seen in deep images of the sky are small low-mass galaxies that have experienced a short epoch of star formation at redshifts 0.5<~z<~1 and have since faded into low-luminosity, low-surface-brightness objects. Such a sc…

1998 • Monthly Notices of the Royal Astronomical Society

eHST 49

Dissecting Capella's Corona: GHRS Spectra of the Fe XXI λ1354 and He II λ1640 Lines from Each of the Capella Stars

DOI: 10.1086/305075 Bibcode: 1998ApJ...492..767L

Brown, Alexander; Wood, Brian E.; Osten, Rachel A. +1 more

We report on moderate (λ/Δλ = 20,000) and high (λ/Δλ = 90,000) resolution spectra of the 104-day period Capella binary system (HD 34029) obtained with Hubble Space Telescope's Goddard High-Resolution Spectrometer (GHRS) on 1995 September 9 and 1996 April 9. The observations include a long-duration, moderate-resolution spectrum of the coronal Fe XX…

1998 • The Astrophysical Journal

eHST 49

Radiative Transfer Models of Emission and Absorption in the H₂O 6 Micron Vibration-Rotation Band toward Orion-BN-KL

DOI: 10.1086/311503 Bibcode: 1998ApJ...502L.169G

Cernicharo, José; van Dishoeck, Ewine F.; Wright, Christopher M. +2 more

We report the spectrum of Orion-BN/KL between 5.3 and 7.2 µm observed with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory. H₂O lines of the ν₂=1-0 bending mode with λ < 6.3 µm (the R-branch) are observed in absorption, while lines with λ > 6.3 µm (the P-branch) are obse…

1998 • The Astrophysical Journal

ISO 49

Halo stars in the immediate solar neighbourhood

DOI: 10.48550/arXiv.astro-ph/9708209 Bibcode: 1998A&A...329...81F

Jahreiß, H.; Fuchs, B.

We have searched the Fourth Catalogue of Nearby Stars for halo stars and identified 15 subdwarfs and a high velocity white dwarf in the solar neighbourhood. This search was motivated mainly by the recent determinations of MACHO masses of about 0.5cal M_sun, which are typical for halo dwarfs. The local mass density of these stars is 1.5*10(-4) cal …

1998 • Astronomy and Astrophysics

Hipparcos eHST 48

Bar-driven evolution of S0s: the edge-on galaxy NGC 4570

DOI: 10.1046/j.1365-8711.1998.01616.x Bibcode: 1998MNRAS.298..267V

van den Bosch, Frank C.; Emsellem, Eric

We present circumstantial evidence that the central region of the edge-on S0 galaxy NGC 4570, which harbours a 150-pc scale nuclear disc in addition to its main outer disc, has been shaped under the influence of a small (~500 pc) bar. This is based on the discovery of two edge-on rings, the locations of which are consistent with the inner Lindblad…

1998 • Monthly Notices of the Royal Astronomical Society

eHST 48

A New Analysis of RR Lyrae Kinematics in the Solar Neighborhood

DOI: 10.1086/300568 Bibcode: 1998AJ....116.1724M

Martin, John C.; Morrison, Heather L.

Full space velocities are computed for a sample of 130 nearby RR Lyrae variables using both ground-based and Hipparcos proper motions. In many cases proper motions for the same star from multiple sources have been averaged to produce approximately a factor of 2 improvement in the transverse space velocity errors. In most cases, this exceeds the ac…

1998 • The Astronomical Journal

Hipparcos 48

Clouds of High Contrast on Uranus

DOI: 10.1126/science.280.5363.570 Bibcode: 1998Sci...280..570K

Karkoschka, Erich

1998 • Science

eHST 48

Cosmological Parameters from Multiple-Arc Gravitational Lensing Systems. I. Smooth Lensing Potentials

DOI: 10.1086/305892 Bibcode: 1998ApJ...502...63L

Link, Robert; Pierce, Michael J.

We describe a new approach for the determination of cosmological parameters using gravitational lensing systems with multiple arcs. We exploit the fact that a given cluster can produce multiple arcs from sources over a broad range in redshift. The coupling between the critical radius of a single arc and the projected mass density of the lensing cl…

1998 • The Astrophysical Journal

eHST 48

Seismic Holography of Solar Activity

DOI: 10.1086/305933 Bibcode: 1998ApJ...502..968B

Braun, D. C.; Lindsey, C.; Fan, Y. +1 more

Helioseismic images of sunspots show a remarkable acoustic anomaly surrounding the sunspot. We applied the computational formalism of ``helioseismic holography'' to SOHO-MDI observations to render acoustic images of NOAA AR 7973, an active region containing a moderately large sunspot. The results of this study are based on simple ``acoustic power …

1998 • The Astrophysical Journal

SOHO 48