The equivalent width and central depth data of Mn 539.4 nm solar spectral line, observed in the period from 1979 to 1992 at Kitt Peak Observatory, was analyzed in pursuit for periodic changes. As the observations are highly unevenly sampled, test if the periods really exist in the observed data was needed. Two different methods for spectral

The integrated galaxial initial mass function (IGIMF) is the relevant distribution function containing the information on the distribution of stellar remnants, the number of supernovae, and the chemical enrichment history of a galaxy. Since most stars form in embedded star clusters with different masses, the IGIMF becomes an integral of the assumed

We present VR magnification ratios of the double quasar Q0957+561AB, which are inferred from frames taken with the 2.56m Nordic Optical Telescope. From two different photometric techniques (pho2comC and psfphot) and a reasonable range for the time delay in the system (415-430 days), we find optical continuum ratios depending on the wavelength

We present the results of a theoretical investigation of the impact of NLTE effects and of granulation inhomogeneities on the iron and oxygen abundances in the metal-poor star HD 140283 and in the Sun. Our analysis is based on both the classical one-dimensional (1D) stellar atmosphere models and on a new generation of three-dimensional (3D)

Given its general importance for studies of star formation at all redshifts, the issue of the heating mechanism for the warm/cool dust in luminous AGN is one of the key problems in extragalactic astrophysics. We propose to address this issue by using the unique high sensitivity capability of the Spitzer to make a mid- to far-IR (MFIR) photometric

We describe TRILEGAL, a new populations synthesis code for simulating the stellar photometry of any Galaxy field. The code attempts to improve upon several technical aspects of star count models, by: dealing with very complete input libraries of evolutionary tracks; using a stellar spectral library to simulate the photometry in virtually any broad