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The Distant Future of Solar Activity: A Case Study of beta Hydri. III. Transition Region, Corona, and Stellar Wind
Linsky, J. L.; Simon, T.; Ayres, T. R. +4 more
The paper investigates the secular decay of solar-type activity through a detailed comparison of the present sun with the very old solar-type star, Beta Hyi, taken as a proxy of the future sun. Analyses of successive atmospheric layers are presented, with emphasis of the outermost parts. The FUV emission lines for the transition zone are among the…
Observations of electron plasma waves upstream of the Jovian bow shock
Kellogg, P. J.; MacDowall, R. J.; Canu, P. +3 more
The Ulysses spacecraft encountered the planet Jupiter in February 1992, on its journey towards high heliospheric latitude. During the approach to the planet, as well as on the outbound pass, while receding from the Jovian bow shock, the Plasma Frequency Receiver that is part of the Unified Radio and Plasma Wave experiment (URAP) recorded bursts of…
Quantitative Spectroscopy of K 648 --the PNN of Ps1 in the Globular Cluster M15
Dreizler, Stefan; Werner, Klaus; Heber, Ulrich
We report preliminary results of a quantitative study of high resolution UV and optical spectra of K648 obtained with the Hubble Space Telescope and the Calar Alto 3.5 m telescope, respectively. Using state of the art NLTE model- atmospheres we determine atmospheric parameters and the abundances of hydrogen, helium and carbon. K648 is found to be …
Damped Lyman-Alpha Absorption in Q0957+561A, B
Turnshek, David A.; Bohlin, Ralph C.
A series of archival IUE low-dispersion spectral observations of the double quasar Q0957 + 561A, B are analyzed. The components of this gravitationally lensed quasar are separated by ~6". Damped Lyα absorption at redshift z_abs_ = 1.3911 with neutral hydrogen column density N(H I) ~ 7 x 10^19^ cm^-2^ is present in the spectra of both the A and B c…
High-velocity spectra features in V854 Centauri : evidence for dust formation ?
Lawson, W. A.; Whitney, B. A.; Clayton, G. C. +1 more
Low-dispersion lUE spectra of V854 Cen show apparent shifts or splitting in the λ2325 C II], λ2800 Mg II, λ2851 Mg I and λ2965 C I lines which, if kinematic, indicate velocities in excess of 1000 km s-1. The variations are seen in all the UV emission lines simultaneously. The line splitting seems to occur at times near phase 0.0 (maximu…
Evidence for Precession of the R Aquarii Jet
Hollis, J. M.; Michalitsianos, A. G.
Several models of the R Aqr northeast jet have been proposed which attempt to explain the presence of shock excitation, resulting in a confusing picture of this nearest astrophysical jet. This paper compares observations of the jet in the R Aqr system with the HST's Faint Object Camera (FOC) and radio continuum images acquired with the VLA. The fo…
Clock-like behavior of Jovian continuum radiation
Kaiser, M. L.; Desch, M. D.; Farrell, W. M.
Ulysses URAP observations of escaping Jovian continuum radiation show a persistent 10 h variation in amplitude which can best be explained by a clock like model. The continuum shows a moderately strong preference to reach maximum intensity when the 0°-90° System III longitude sector faces the Sun.
Deep Hubble Space Telescope Imaging of 53WO44: an SO Radio Galaxy at z=0.311
Keel, William C.; Windhorst, Rogier A.
We present images with the Wide-Field Camera (WFC) and Faint-Object Camera (FOC) of the radio galaxy 53W044, as part of a morphological study of the faint radio-source population. The WFC images are used to examine the structure of the galaxy, and show evidence for a significant disk (contributing 18%-20% of the light in the observed V and I bands…
Large-amplitude magnetic pulses downstream of the Jovian bow shock: Ulysses observations
Tsurutani, Bruce T.; Smith, Edward J.; Balogh, Andre +2 more
We report the first finding of large-amplitude magnetic pulses in the Jovian magnetosheath. The pulses are highly compressional with Δ| B|/| B| ranging from 0.5 to 2.0. Each pulse contains a full 360° phase rotation. These solitary waves are propagating at an angle nearly orthogonal to the ambient magnetic field ( θkB > 83°). A deter…
Further constraints on the warm absorber in MR 2251-17.8 from GINGA and EXOSAT observations.
Mineo, T.; Stewart, G. C.
Analysis of a Ginga observation of MR 2251 - 17.8 is presented. The source is in a relatively low emission state, with a high absorbing column density. This result is consistent with the previous EXOSAT observations, where a strong correlation between the flux and the column density was detected. The Ginga spectrum and the entire EXOSAT spectral d…