0000000000451479
AUTHOR
M. J. Fernandez-figueroa
Recent Measures of CaII H and K Chromospheric Fluxes in a Sample of RS CVn Systems
In this contribution we present the current status of a high resolution H and K spectroscopic survey of RS CVn and BY Dra systems which is being performed at our Department. The reduction and calibration procedures used in the extraction of emission fluxes are analyzed. We discuss the preliminary results for three of the RS CVn systems: HR 5110, Z Her and RT Lac.
Caii H and K spectroscopic observations in active binary systems
We have performed high resolution spectroscopic observations of five active binary systems in the Caii H and K lines at La Palma Observatory. We present the absolute fluxes calculated at the surface of the stars and we discuss the spectral characteristics observed, presence of double emissions and phase variations.
Hβ photometry for UVBY standard stars
From 1984 to 1986 the authors made several observational campaigns at Calar Alto and La Palma Observatories using the uvby and β photometric systems to monitor a selected sample of late-type variable stars. In this paper they present the β values for 38 uvby standard stars to contribute to the uvby-β calibration works on late-type stars. In the final discussion, the β computed values are plotted against the Stroemgren b-y, m_(1), and c_(1) indices.
Weak Flares on M-Dwarfs
We have investigated the physics of flares in M-dwarfs by means of optical/X-ray observations and modeling. The great efficiency of current optical spectrographs and detectors has allowed us to detect and analyze a great number of non white-light flares with intermediate spectral resolution and high temporal resolution. Although this kind of flares is the most typical on the Sun, few such events have been so far recorded on stars. We have obtained the physical parameters of the chromospheric flaring plasma (electron temperature, electron density, optical depth and temperature of the underlying source) by using a model that minimizes the difference between the observed Balmer decrements and …