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Chapter and Conference Paper
Physical Parameters of Evolved Stars in Clusters and in the Field from Line-depth Ratios
We present a high-resolution spectroscopic analysis of two samples of evolved stars selected in the field and in the intermediate-age open cluster IC 4651, for which detailed measurements of chemical compositi...
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Chapter
Hα Line and Photometric Variability in Magnetically Active Stars
The spatial association and evolution of photospheric and chromospheric active regions, on the Sun, traces the emersion of magnetic flux tubes. We show that atmospheric phenomena observed in solar-like stars c...
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Chapter
Rotational Modulation of Hα Emission in RS CVN Systems
The spectroscopic Hα observations of five RS CVn systems (UX Ari, HR 1099, Z Her, HK Lac, RT Lac) and of the contact system VW Cep here discussed were obtained in 1989, 1990, 1991, 1993 and 1994 with the 91-cm...
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Chapter and Conference Paper
Extending the Presence of Chromospheres and Coronae to Middle A-Type Stars
Recently, we presented new evidence for the presence of high temperature layers (chromospheres, transition zones, and coronae) above the photosphere of late A-type stars. Here we summarize some of these result...
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Chapter and Conference Paper
The age evolution of Ca II emission in late type stars
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Chapter
The Spin-Down of Main Sequence Stars Based on Observed Magnetic Field Strength
In the present paper we try to reproduce the observed dependence of rotation decay of main sequence stars in the mass range 1.1–0.5 M⊙. We adopt a radial magnetic field structure which yields the t-1/2 relation a...
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Chapter and Conference Paper
The onset of chromospheres in A-type stars: The altair affair
Here we present preliminary results on the study of the chromosphere of Altair from Lα high dispersion profiles. We report also the detection of Lα chromospheric emission from α Cep (A7 V) and β TrA (F0 V) with t...
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Chapter
Rotational Evolution of Low-Mass Stars
From observational data on rotation periods and ages we deduce the evolution of surface rotational velocity of low-mass main sequence stars from the age of the Pleiades to the solar age. The t1/2 increase of the ...
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Chapter and Conference Paper
Rotation period evolution of late MS stars
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Chapter and Conference Paper
Chromospheric Emission and Rotation of Main Sequence Stars
Here we present a quatitative approach to the problem of the chromospheric emission and rotation in main sequence stars based on a consistent analysis of recent published data of stars from F8 to K5. This anal...
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Chapter and Conference Paper
IUE Spectra of RS CVn Stars
The characteristic optical light curves of RS CVn — and BY Dra-type variables are believed to represent non-uniform distribution of dark spots akin to sunspots which are revealed by rotation. By analogy with t...
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Chapter and Conference Paper
Twenty Years of Dedicated Photometry of Rs CVn at Catania Observatory
We present a complete set of yearly seasonal light curves (LC) of RS CVn obtained from 1963 to 1982 at Catania Observatory, integrated with two LCs obtained by Ludington (1978) in 1975 and 1976. This unique ob...
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Chapter and Conference Paper
Features of the Wave-Like Distortion in Some RS CVn Binaries
One of the outstanding features of RS CVn-type binaries is the changing shape of the so called “wave-like distortion” or “photometric wave” (PW) and its phase migration on the light curve (LC). Here we present...
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Article
IUE observations of an active region of HD206860
THE chromospheric Mg II h and k lines seem to have doubly reversed emission core in the spectra of the Sun and of solar and late type stars. In the solar spectrum the general appearance of Mg II h and k is very s...
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Chapter
Absolute Fluxes of K Chromospheric Emission on the H-R Diagram
Continuing our previous analysis of the chromospheric emission (Blanco et al.,1974), absolute fluxes of the K emission line have been evaluated from 10 Å mm−1 spectrograms of the O. C. Wilson collection for 31 F5...
