Search Publications
Astrophysics in 1999
Aschwanden, Markus J.; Trimble, Virginia
The year 1999 saw the arrival of a star with three planets, a universe with three parameters, and a solar corona that could be heated at least three ways. In addition, there were at least three papers on every question that has ever been asked in astrophysics, from ``Will the Universe expand forever?'' to ``Does mantle convection occur in one or t…
Single Be stars as binary ejecta?
Rinehart, S. A.
Among the mechanisms suggested for the creation of discs around Be stars is interaction with binary companions. This idea has largely been dismissed, because the majority of Be stars have no observed companion. This difficulty can be circumvented if single Be stars are actually ejected from binary systems (owing, for instance, to the supernova of …
SERTS-97 Measurements Of Relative Wavelength Shifts In Coronal Emission Lines Across A Solar Active Region
Thompson, W. T.; Davila, J. M.; Thomas, R. J. +1 more
We used slit spectra from the 18 November 1997 flight of Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS-97) to measure relative wavelength shifts of coronal emission lines as a function of position across NOAA active region 8108. The shifts are measured relative to reference wavelengths derived from spectra of the…
QSO mass constraints from gravitational lensing studies of quasar pairs. The cases of Q1548+114 A & B and Q1148+0055 A & B
Surdej, J.; Sluse, D.; Claeskens, J. -F. +2 more
New constraints on the mass of quasars are derived from gravitational lensing studies of the QSO pairs Q1548+114 A & B and Q1148+0055 A & B, for which new ground-based and Hubble Space Telescope (HST) direct imagery have been obtained. In the case of Q1548+114 A & B, QSO A has been resolved into its host galaxy and a close companion. T…
Monochromatic X-ray source for calibrating X-ray telescopes
Bräuninger, H.; Burkert, W.; Arkadiev, V. +5 more
A quasi-monochromatic X-ray source for calibrating X-ray space telescopes was developed, manufactured and tested. The source consists of a powerful X-ray tube of an open type with changeable anode targets and a regulated double-crystal monochromator.
The effect of different ion fraction datasets on plasma diagnostics
Landini, M.; Landi, E.; Gianetti, D.
In the present work the element abundances in an active region observed on the solar disk are studied using EUV spectral lines observed by the Coronal Diagnostic Spectrometer (CDS) on board of SOHO. Making use of the large number of lines identified in the CDS spectral range and of the instrument imaging capability, the abundances of several eleme…
V1073 Cygni: A New Light Curve and Analysis
Morris, Steven L.; Naftilan, Stephen A.
A new CCD light curve of the A-type W UMa star V1073 Cygni has been obtained, and the differential-corrections method of Wilson and Devinney was used to compute a new set of system parameters. The same analysis has been applied to the other photometric light curves in the literature, including the Hipparcos light curve. A new ephemeris is determin…
Recurrence in MeV proton fluxes and anisotropies at 5 AU from the Sun
Balogh, A.; Dalla, S.
We report the observation of a recurrent pattern in proton fluxes and anisotropies at 5.2 AU from the Sun, made by the Anisotropy Telescopes on board the Ulysses spacecraft between April 1998 and May 1999, during the rising phase of solar cycle 23. The time delay between recurrent features of the pattern is not constant and increases from 122 to 1…
Coronal Mass Ejections and the Solar Wind: New Results from LASCO
Howard, R. A.; Dere, K. P.; Brueckner, G. E.
The LASCO and EIT experiments on SOHO have provided a revolutionary picture of coronal dynamics. In the past, the corona has largely been thought to be a region where the evolution of the coronal structures occurred on relatively large time scales, aside from the intermittent coronal mass ejection. The outflows in the polar coronal holes were larg…
Non-Radial Unipolar Coronal Streamers in Magnetically High Latitudes and Radial Bipolar Streamers at the Magnetic Equator of the Sun
Shibata, K.; Dere, K. P.; Saito, Takao +1 more
The complex structure of coronal streamers can be better understood by their classification into two classes: non-radial unipolar streamers emanating from magnetically high latitudes, and radial bipolar streamers emanating from the magnetic equator. The coronal streamers observed during the total solar eclipses of July 11,1991 and February 26, 199…