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Stokes profiles of sunspot penumbrae show distinct asymmetries, which point to gradients in the velocity field and in the magnetic field. We present spectropolarimetric measurements of the Stokes vector in the neutral iron triplet at 1564.8 nm taken with the Tenerife Infrared Polarimeter (TIP) at the German Vacuum Tower Telescope (VTT) in Tenerife

We present a spectrophotometric study of short-term optical variability in the quiescent black hole X-ray transient V404 Cyg focusing on two nights of Hα spectroscopy. We find significant variability, with both the Hα line and the continuum varying in a correlated way. This includes both dramatic flares lasting a few hours in which the line flux

Magnetic fields play a key role in most astrophysical systems, from the Sun to active galactic nuclei. They can be studied through their effects on atomic energy levels, which produce polarized spectral lines. In particular, anisotropic radiation `pumping' processes (which send electrons to higher atomic levels) induce population imbalances that

Ellipsoidal lightcurves of XTE J1118+48 during its decline to quiescence are strongly contaminated with a superhump wave. A PDM period analysis yields Psh = 0.17049(1) d i.e. 0.3% longer than the orbital period. This implies a disc precession period Pprec ~52 d and q ~0.03.

We present spherically symmetric and plane-parallel photoionization models of NGC 346, an H II region in the Small Magellanic Cloud. The models are based on CLOUDY and on the observations of Peimbert, Peimbert, & Ruiz. We find that approximately 45% of the H ionization photons escape from the H II region, providing an important ionizing source for