A Decade Of Starspot Activity On The Eclipsing Short-Period RS Canum Venaticorum Star WY Cancri: 1988-1997

We present optical photometry of the short-period eclipsing RS CVn system WY Cancri for the years 1988–1997. For each light curve, we model the distortion waves in order to study the behavior of starspots in this system. After removing the spot effects f

Towards Closing the Window on Strongly Interacting Dark Matter: Far-Reaching Constraints from Earth's Heat Flow

We point out a new and largely model-independent constraint on the dark matter scattering cross section with nucleons, applying when this quantity is larger than for typical weakly interacting dark matter candidates. When the dark matter capture rate in Earth is efficient, the rate of energy deposition by dark matter self-annihilation products would grossly exceed the measured heat flow of Earth. This improves the spin-independent cross section constraints by many orders of magnitude, and closes the window between astrophysical constraints (at very large cross sections) and underground detector constraints (at small cross sections). In the applicable mass range, from about 1 to about 10^{10} GeV, the scattering cross section of dark matter with nucleons is then bounded from above by the latter constraints, and hence must be truly weak, as usually assumed.Comment: 12 pages, 2 figures; minor updates to match published versio

Locating the festival, positioning the feast: natural and calendar festivals in medieval Slovenia

The astronomical cycles and occurrences of the Sun, Moon, planets and certain star constellations were well known to prehistoric, Roman and medieval communities. Archaeoastronomy studies how ancient societies incorporated this knowledge into various aspects of past cultures. The discipline draws on modern astronomy, geodesy, physics, statistics, anthropology, ethnology and archaeology to study and interpret a wide range of source materials, from structural alignments to art, artefacts and inscriptions. This paper presents archaeoastronomical research on the orientation of Romanesque churches across the territory of modern-day Slovenia, focusing on an array of medieval festivals associated with the solstices and equinoxes. It demonstrates a profound connection between these festivals and the alignment of churches

Observational Studies Of Magnetically Active Stars

Multi-wavelength observing has been particularly fruitful in cool star research. There have been some wellobserved examples, eg AB Dor, though ambiguity remains. This raises issues of data information content and model parameter determinacy, which are examined firstly in an optical context. We then widen the discussion to show how multi-site and multi-wavelength data can be combined to point to better constrained models. Particular cases, involving near-simultaneous radiometry and photometry, are discussed to clarify such modelling. I. ACTIVE STARS There are extensive sources of recent information on this rapidly expanding subject (see e.g. Stellar Surface Structure eds. K. Strassmeier and J. L. Linsky, 1996). The present account can only sketch, with its own particular slant, some salient points, though a few new results will be ventured. Stellar `activity' is strongly associated with stars showing phenomena similar to those of the close binary system RS CVn (Ramsey, 1990; Strassmei..