The structure and spectra of irradiated secondaries in close binaries (pre-CVs)

Many stars evolve not alone but along one or more companions. While the evolution of single isolated stars is well predicted by theoretical calculations, close binary systems with their interactions are on the one hand far more difficult to handle, but on the other hand well constrained in their masses and sizes. One mechanism thought to produce such close binaries is the Common Envelope Evolution (CEE). Especially young post CEE binaries show great temperature differences between both components of about a factor 10 at a separation of just a few solar radii. This work focuses on close binary systems with a hot primary component (e.g. a subdwarf O-type star (sdO)) and a much cooler secondary component (e.g. a main-sequence star), which is heavily influenced by external radiation originating from the first. The technique to include external radiation into the stellar atmosphere code PHOENIX, i.e., the deviation of the outer boundary condition and the change in the temperature correction method, is described in detail. To concentrate on the irradiation effect, other difficulties such as asymmetric effects due to tear-drop shaped stars, ongoing mass accretion or shadows of a circumbinary disc, are avoided by selecting pre-cataclysmic variables (pre CVs) out of the class of close binaries as laboratory. The total eclipsing binary system UU~Sagittae is used as an example for massive irradiation and observed spectral features in the optical are fitted ...thesi

Replication data for: Lusoria - Ein Römerschiff im Experiment: Rekonstruktion - Tests - Ergebnisse

How fast to roman warships sail and how useful is the sail if the wind comes at an angle? In order to test the sailing and rowing characteristics of Roman warships, a series of experiments was conducted. The bases for this is a roman riverboat of the type "Navis Lusoria" that was reconstructed in Regensburg in full scale. This boat was equipped with a Silva Marine NX2 system to record boat speed, wind speed and direction, boat position and speed over ground and other parameters not a vital for this study. In addition the number of oar strokes per minute was recorded by hand. In this study, we release the digital files written by the NX2 system and the digitized noted. From this data we calibrated the log response and calculated a polar diagram, which shows how fast the boat can go for each wind speed and wind direction

Replication data for: Projekt Römerschiff: Nachbau und Erprobung für die Ausstellung ’2000 Jahre Varusschlacht’

How fast to roman warships sail and how useful is the sail if the wind comes at an angle? In order to test the sailing and rowing characteristics of Roman warships, a series of experiments was conducted. The bases for this is a roman riverboat of the type "Oberstimm" that was reconstructed in Regensburg in full scale. This boat was equipped with a Silva Marine NX2 system to record boat speed, wind speed and direction, boat position and speed over ground and other parameters not a vital for this study. In addition the number of oar strokes per minute was recorded by hand. In this study, we release the digital files written by the NX2 system and the digitized noted. From this data we calibrated the log response and calculated a polar diagram, which shows how fast the boat can go for each wind speed and wind direction

Testing of Ship "Oberstimm 1" on the Lake Ratzburger

Данная статья содержит результаты вычислительных измерений ходовых качеств реконструированного римского корабля типа "Оберштимм-1"