While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear

Aims: We study how IMF sampling affects the ionizing flux and emission line spectra of low mass stellar clusters. Methods: We performed 2 × 106 Monte Carlo simulations of zero-age solar-metallicity stellar clusters covering the 20-106 M&sun; mass range. We study the distribution of cluster stellar masses, Mclus, ionizing fluxes, Q(H0), and

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We present synthetic spectral energy distributions (SEDs) for single-age, single-metallicity stellar populations (SSPs) covering the full optical spectral range at moderately high resolution [full width at half-maximum (FWHM)=2.3Å]. These SEDs constitute our base models, as they combine scaled-solar isochrones with an empirical stellar spectral

Simple gravitational lens models usually suffice to reproduce the positions of lensed quasar images, but they have problems to reproduce their optical flux ratios. The so-called flux ratio anomalies are thought to be produced by small-scale structure in the lens galaxies (microlensing).