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A statistical analysis of the metallicities of nine old superclusters and moving groups
Taylor, B. J.
Using both high-dispersion and low-resolution data, the metallicities of nine old moving groups and superclusters are analyzed. These stellar groupings include the HR 1614 and Hyades superclusters and the Wolf 630, zeta Her, 61 Cyg, HR 1614, sigma Pup, eta Cep, and Arcturus groups. Samples of these stellar groupings are drawn from Eggen's membersh…
ISO spectroscopy of young intermediate-mass stars in the BD+40deg4124 group
Tielens, A. G. G. M.; van den Ancker, M. E.; Wesselius, P. R.
We present the results of ISO SWS and LWS grating scans towards the three brightest members of the BD+40deg4124 group in the infrared: BD+40deg4124 (B2Ve), LkHα 224 (A7e) and the embedded source LkHα 225. Emission from the pure rotational lines of H_2, from ro-vibrational transitions of CO, from PAHs, from H i recombination l…
Multiple and variable X-ray sources in the globular clusters omega Cen, NGC 6397, NGC 6752, and Liller 1
Verbunt, F.; Johnston, H. M.
We detect stars from the Hipparcos and Tycho Catalogues in the field of view of observations with the ROSAT HRI of three globular clusters. We use the positions of these stars to reduce the systematic error in the positions of X-ray sources in the clusters to ~ 2'' for omega Cen and NGC 6752, and 1'' for NGC 6397. We detect three X-ray sources in …
Active eclipsing binary RT Andromedae revisited
Chochol, D.; Vittone, A. A.; Errico, L. +4 more
All available photometric and spectroscopic data of the short-period RS CVn-like binary RT And have been reanalyzed in a homogeneous way. The long-term orbital period change is explained by two period jumps, a continuous period decrease combined with the light-time orbit or two light-time orbits. UBVRIJK light curves without maculation effects tog…
Properties and nature of Be stars. XIX. Spectral and light variability of 60 Cygni
Harmanec, P.; Huang, L.; Cao, H. +11 more
An analysis of electronic spectra secured between 1992 and 1999 at the Haute Provence, Ondřejov and Dominion Astrophysical Observatories and of differential UBV measurements of 60 Cyg obtained between 1984 and 1999 at Hvar, San Pedro Mártir, Toronto and Xinglong Observatories, the all-sky Hipparcos satellite H_p photometry transformed to Johnson V…
The structure of Algol's corona: a consistent scenario for the X-ray and radio emission
Schmitt, J. H. M. M.; Micela, G.; Favata, F. +2 more
We present a systematic analysis of the four known large X-ray flares detected to date on the eclipsing binary system Algol, using an approach based on hydrodynamic simulations of decaying flaring loops including sustained heating. This method yields, for the large BeppoSAX Algol flare of Aug. 1997 (where a geometrical estimate of the size of the …
Network and internetwork: a compared multiwavelength analysis
Falchi, A.; Cauzzi, G.; Falciani, R.
We analyze the temporal behavior of Network Bright Points (NBPs) using a set of data acquired during coordinated observations between ground-based observatories (mainly at the NSO/Sacramento Peak) and the Michelson Doppler Interferometer onboard SOHO. We find that, at any time during the observational sequence, all the NBPs visible in the NaD_2 im…
Structure and dynamics of an active region loop system observed on the solar disc with SUMER on SOHO
Marsch, E.; Lanzafame, A. C.; Brooks, D. H. +3 more
In this paper we present and discuss spectra obtained by SUMER on SOHO from an active region loop system observed on the solar disc, close to the central meridian, on July 26th, 1996. The region was observed with a spatial resolution of about 2arcsec by 2arcsec in emission lines forming in the transition region and inner corona, with the aim of in…
Giant macro-spicule as observed by CDS on SOHO
Doyle, J. G.; Banerjee, D.; O'Shea, E.
We examine spectral time series of coronal line Mg ix 368 Ä and transition region line O v 629 Ä, observed with the Coronal Diagnostic Spectrometer (CDS) onboard the SOHO spacecraft. Primarily we were looking for intensity and velocity oscillations in polar plumes, however by chance we detected a giant macro-spicule at the limb and were able to fo…
Multi-wavelength bispectrum speckle interferometry of R Cas and comparison of the observations with Mira star models
Weigelt, G.; Hofmann, K. -H.; Balega, Y. +1 more
We present diffraction-limited (30 mas) bispectrum speckle interferometry observations of the Mira star R Cas with the Russian 6 m SAO telescope. The speckle interferograms were recorded through narrow-band interference filters with centre wavelength/bandwidth of 671 nm/6 nm and 714 nm/6 nm (strong TiO absorption band), 700 nm/6 nm (moderate TiO a…