Four colour photometry of binary systems

Three colour photometry of solar limb faculae

The contrasts of limb faculae at various heliocentric angles are observed in three continuum windows largely free of absorption lines. Observations with interference filters show a contrast decrease with wavelength which is not found when using an ‘UBF’ to select the shortest continuum window. Limb faculae in speckle-reconstructed images yield contrasts being typically 1.2 times higher than tho...

Photometry of four binary subdwarf B stars and the nature of their unseen companion stars

We present lightcurves of four binary subdwarf B stars, Ton 245, Feige 11, PG1432+159 and PG1017−086. We also present new spectroscopic data for PG1017−086 from which we derive its orbital period, P = 0.073d, and the mass function, fm = 0.0010±0.0002M⊙. This is the shortest period for an sdB binary measured to-date. The values of P and fm for the other sdB binaries have been published elsewhere...

Four-color and Hp Photometry of Stars

The Four-Colour Theorem

The four-colour theorem, that every loopless planar graph admits a vertex-colouring with at most four different colours, was proved in 1976 by Appel and Haken, using a computer. Here we give another proof, still using a computer, but simpler than Appel and Haken’s in several respects. 1 Research partially performed under a consulting agreement with Bellcore, partially supported by DIMACS Center...

The Potential of Multi - Colour Photometry for Pulsating

We investigate the potential of multi-colour photometry for partial mode identification in both long-and short-period variable subdwarf B stars. The technique presented is based on the fact that the frequency dependence of an oscillation's amplitude and phase bears the signature of the mode's degree index l, among other things. Unknown contributing factors can be eliminated through the evaluati...