Knowledge of the solar irradiance background is of great importance to solar and stellar physics. In particular, its contribution to the solar oscillations power spectrum is highly relevant as it represents the ultimate limit to the sensitivity of solar oscillations' observations. An analysis of the power spectra of the solar photometric data

A low dispersion objective-prism survey for low-redshift emission-line galaxies (ELGs) is being carried out by the University Complutense de Madrid with the Schmidt telescope at the German-Spanish Observatory of Calar Alto (Almeria, Spain). A 4° full aperture prism, which provides a dispersion of 1950Å/mm, and IIIa-F emulsion combination has been

For the first time have been able to observe and combine a large number of observables for two SO galaxies NGC 5689 and NGC 7332, in order to apply a detailed analysis of their constituent stellar populations. We will discuss our main results from the present study of the two SO galaxies NGC 5689 and NGC 7332, on the basis of our single-age, single

We report here first results concerning stellar oxygen abundances in M33. Non-LTE model atmosphere and non-LTE line formation calculations were used to determine the oxygen abundance of B-type supergiants. By choosing stars located at different projected radial distances to the center of M33, we are able to determine the oxygen abundance gradient

We have obtained medium resolution spectra of the neutron star X-ray transient Aql X-1 during quiescence. We determine the spectral type of the companion star to be K1 and also estimate its rotation speed to be 62(+30/-20) km/s. By measuring the width of the H-alpha emission line profile of the accretion disc, we estimate the binary inclination to

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