Context. Radial-velocity variations of the K giant star Aldebaran (α Tau) were first reported in the early 1990s. After subsequent analyses, the radial-velocity variability with a period of ∼629 d has recently been interpreted as caused by a planet of several Jovian masses. Aims. We want to further investigate the hypothesis of an extrasolar planet around Aldebaran. Methods. We combine 165 new radial-velocity measurements from Lick Observatory with seven already published data sets comprising 373 radial-velocity measurements. We perform statistical analyses and investigate whether a Keplerian model properly fits the radial velocities. We also perform a dynamical stability analysis for a possible two-planet solution. Furthermore, the possibility of oscillatory convective modes as cause for the observed radial-velocity variability is discussed. Results. As best Keplerian fit to the combined radial-velocity data we obtain an orbit for the hypothetical planet with a smaller period (P = 607 d) and a larger eccentricity (e = 0.33 ± 0.04) than the previously proposed one. However, the residual scatter around that fit is still large, with a standard deviation of 117 ms−1. In 2006/2007, the statistical power of the ∼620 d period showed a temporary but significant decrease. Plotting the growth of power in reverse chronological order reveals that a period around 620 d is clearly present in the newest data but not in the data taken before ∼2006. Furthermore, an apparent phase shift between radial-velocity data and orbital solution is observable at certain times. A two-planet Keplerian fit matches the data considerably better than a single-planet solution, but poses severe dynamical stability issues. Conclusions. The radial-velocity data from Lick Observatory do not further support but in fact weaken the hypothesis of a substellar companion around Aldebaran. Oscillatory convective modes might be a plausible alternative explanation of the observed radial-velocity variations.

Escalating observations of exo-minor planets and their destroyed remnants both passing through the solar system and within white dwarf planetary systems motivate an understanding of the orbital history and fate of exo-Kuiper belts and planetesimal discs. Here we explore how the structure of a 40 − 1000 au annulus of planetesimals orbiting inside of a solar system analogue that is itself initially embedded within a stellar cluster environment varies as the star evolves through all of its stellar phases. We attempt this computationally challenging link in four parts: (1) by performing stellar cluster simulations lasting 100 Myr, (2) by making assumptions about the subsequent quiescent 11 Gyr main-sequence evolution, (3) by performing simulations throughout the giant branch phases of evolution, and (4) by making assumptions about the belt's evolution during the white dwarf phase. Throughout these stages, we estimate the planetesimals' gravitational responses to analogues of the four solar system giant planets, as well as to collisional grinding, Galactic tides, stellar flybys, and stellar radiation. We find that the imprint of stellar cluster dynamics on the architecture of 100 km-sized exo-Kuiper belt planetesimals is retained throughout all phases of stellar evolution unless violent gravitational instabilities are triggered either (1) amongst the giant planets, or (2) due to a close ( 10 3 au) stellar flyby. In the absence of these instabilities, these minor planets simply double their semimajor axis while retaining their primordial post-cluster eccentricity and inclination distributions, with implications for the free-floating planetesimal population and metal-polluted white dwarfs.

Zusammenfassung: Berichtet wird über zwei getrennte Untersuchungen, denen gemeinsam der bedingt-prospektive Ansatz und der Umstand waren, dass (in verkürzten Versionen) die einschlägigen Krankheitsprädiktoren von Grossarth-Maticek (1989) zum Einsatz kamen, d.h. Skalen zur Erfassung von Typ 1 (= der Krebs-Disposition) bzw. solche zur Erfassung von Typ 2 (= Disposition für koronare Herz-Krankheiten, KHK). An der Studie zur Vorhersage von Mammakarzinom (I) nahmen n = 55 Patientinnen mit benignen und n = 32 Patientinnen mit malignen Erkrankungen teil, an derjenigen zur Vorhersage von KHK (II) n = 61 Personen beiderlei Geschlechts mit positivem und n = 20 Personen mit negativem Befund in der Coronarangiographie sowie n = 60 Patienten mit nicht-kardialer Symptomatik. In multivariaten Analysen erwiesen sich als signifikante Prädiktoren für Mammakarzinom das Alter und der Familienstatus, im weiteren die Stressverarbeitungsstrategien, das Bedürfnis nach Kontrolle, nach sozialer Unterstützung und nach Aggressionsabfuhr; KHK war signifikant durch Alter und Geschlecht sowie die Persönlichkeitsvariablen öffentliche Selbstaufmerksamkeit und Erregbarkeit vorhersagbar. Hingegen trugen die Skalen zur Erfassung von Typ 1 bzw. Typ 2 nichts zur Unterscheidung der Personen mit positivem vs. negativem Befund bei. Die Resultate entsprechen insoweit den Beobachtungen in querschnittlich vorgenommenen Erhebungen.

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