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Physical Conditions of the Coronal Line Region in Seyfert Galaxies
Ferland, Gary J.; Korista, Kirk T.; Ferguson, Jason W.
The launch of the Infrared Space Observatory and new atomic data have opened a window for the study of high-ionization gas in active galactic nuclei (AGNs). We present the results of a large number of photoionization simulations of the ``coronal line'' region in AGNs, employing new atomic data from the Opacity and Iron Projects. Our grid of line e…
Measurements of Frequencies of Solar Oscillations from the MDI Medium-l Program
Kosovichev, A. G.; Scherrer, P. H.; Schou, J. +2 more
Inversions of solar internal structure employ both the frequencies and the associated uncertainties of the solar oscillation modes as input parameters. In this paper we investigate how systematic errors in these input parameters may affect the resulting inferences of the sun's internal structure. Such systematic errors are likely to arise from ina…
Structure function measurements of the intermittent MHD turbulent cascade
Balogh, A.; Horbury, T. S.
The intertmittent nature of turbulence within solar wind plasma has been demonstrated by several studies of spacecraft data. Using magnetic field data taken in high speed flows at high heliographic latitudes by the Ulysses probe, the character of fluctuations within the inertia] range is discussed. Structure functions are used extensively. A simpl…
The stellar population of the globular cluster M 3. II. CCD photometry of additional 10,000 stars.
Cacciari, C.; Carretta, E.; Buonanno, R. +5 more
We present BVI CCD photometry for more than 10,000 stars in the innermost region (0.3'<r<~4') of the globular cluster M 3. When added to the previous photographic photometry by Buonanno et al. (1994A&A...290...69B) reaching as far as r~7', this results in an homogeneous data-set including about 19,000 stars measured in this cluster, whic…
Hubble Space Telescope Ultraviolet Observations of the Cores of M3 and M13
Ferraro, Francesco R.; Paltrinieri, Barbara; Fusi Pecci, Flavio +3 more
We present preliminary results from Hubble Space Telescope (HST)/WFPC2 observations of the central regions of the of the Galactic globular clusters M13 and M3. The clusters are almost identical in most respects, including chemical composition, but there are dramatic differences in both the horizontal-branch (HB) and blue straggler populations. The…
High Carbon in I Zwicky 18: New Results from Hubble Space Telescope Spectroscopy
Garnett, D. R.; Skillman, E. D.; Dufour, R. J. +1 more
We present new measurements of the gas-phase C/O abundance ratio in both the northwest (NW) and southeast (SE) components of the extremely metal-poor dwarf irregular galaxy I Zw 18, based on ultraviolet spectroscopy of the two H II regions using the Faint Object Spectrograph on the Hubble Space Telescope. We determine values of log C/O = -0.63 +/-…
High-Resolution Observations of the Extreme Ultraviolet Sun
Harrison, R. A.; Culhane, J. L.; Fludra, A. +9 more
This paper presents first results of the Coronal Diagnostic Spectrometer (CDS) recently launched aboard the Solar and Heliospheric Observatory (SOHO). CDS is a twin spectrometer, operating in the extreme ultraviolet range 151-785 Å. Thus, it can detect emission lines from trace elements in the corona and transition region which will be used to pro…
The Wide-Band Plasma Wave Investigation
Gurnett, D. A.; Kirchner, D. L.; Huff, R. L.
Application of Spectroscopic Diagnostics to Early Observations with the SOHO Coronal Diagnostic Spectrometer
Young, P. R.; Mason, H. E.; Harrison, R. A. +4 more
The Coronal Diagnostic Spectrometer (CDS) has as a scientific goal the determination of the physical parameters of the solar plasma using spectroscopic diagnostic techniques. Absolute intensities and intensity ratios of the EUV spectral emission lines can be used to obtain information on the electron density and temperature structure, element abun…
The solar disk spectrum between 660 and 1175 Anstroms (first order) obtained by SUMER on SOHO
Wilhelm, K.; Curdt, W.; Lemaire, P. +3 more
SUMER -- Solar Ultraviolet Measurements of Emitted Radiation -- onboard of SOHO -- Solar and Heliospheric Observatory -- obtained its first spectrum on January 25, 1996 near the north polar limb. The range from 660 Angstroms to 1175 Angstroms which has never before been observed with such a good spectral resolution contains a wealth of spectroscop…