Spectroscopy of transiting exoplanets can be used to investigate their atmospheric properties and habitability. Combining radial velocity (RV) and transit data provides additional information on exoplanet physical properties. We detect a transiting rocky planet with an orbital period of 1.467 days around the nearby red dwarf star Gliese 486. The planet Gliese 486 b is 2.81 Earth masses and 1.31 Earth radii, with uncertainties of 5%, as determined from RV data and photometric light curves. The host star is at a distance of ~8.1 parsecs, has a J-band magnitude of ~7.2, and is observable from both hemispheres of Earth. On the basis of these properties and the planet's short orbital period and high equilibrium temperature, we show that this terrestrial planet is suitable for emission and transit spectroscopy.
Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought.
Barnard's star is a red dwarf, and has the largest proper motion (apparent motion across the sky) of all known stars. At a distance of 1.8 parsecs1, it is the closest single star to the Sun; only the three stars in the α Centauri system are closer. Barnard's star is also among the least magnetically active red dwarfs known2,3 and has an estimated age older than the Solar System. Its properties make it a prime target for planetary searches; various techniques with different sensitivity limits have been used previously, including radial-velocity imaging4-6, astrometry7,8 and direct imaging9, but all ultimately led to negative or null results. Here we combine numerous measurements from high-precision radial-velocity instruments, revealing the presence of a low-amplitude periodic signal with a period of 233 days. Independent photometric and spectroscopic monitoring, as well as an analysis of instrumental systematic effects, suggest that this signal is best explained as arising from a planetary companion. The candidate planet around Barnard's star is a cold super-Earth, with a minimum mass of 3.2 times that of Earth, orbiting near its snow line (the minimum distance from the star at which volatile compounds could condense). The combination of all radial-velocity datasets spanning 20 years of measurements additionally reveals a long-term modulation that could arise from a stellar magnetic-activity cycle or from a more distant planetary object. Because of its proximity to the Sun, the candidate planet has a maximum angular separation of 220 milliarcseconds from Barnard's star, making it an excellent target for direct imaging and astrometric observations in the future.
The reorganization through high-temperature annealing of closely-packed pore arrays can be exploited to create ultra-thin (<20 µm) monocrystalline silicon layers that can work as cheap and flexible substrates for both the electronic and the photovoltaic industries. By introducing a periodic diameter modulation along deep etched pores, many thin layers can be produced from a single substrate and in a single technological process. Besides the periodicity, the exact shape of the modulation also has a profound impact on the process and subtle profile changes can lead to important differences on the process outcome. In this paper we study both theoretically and experimentally the effect of the initial profile on the pore reorganization dynamics and the morphology of the thin layers obtained through annealing. We show that process reliability, annealing time and final layer characteristics, all can be engineered and optimized by precisely controlling the initial pore profile.
A total of 2400 incomplete helminthological postmortem examinations were carried out with sheep in 1972-1976. Four species of helminths were found in the liver: D. lanceatum (80.7 per cent), Ech. granulosus (68.4 per cent), F. hepatica (25.6 per cent), and Cyst. tenuicolis (1.7 per cent). Mixed infections were established in 68.2 per cent of the livers: F. hepatica, D. lanceatum, Ech. granulosus--11.5 per cent; F. hepatica, D. lanceatum--6.8 per cent; F. hepatica, Ech. granulosus 3.8 per cent; and D. lanceatum, Ech. granulosus--46.1 per cent. Single worm infections were observed in 26.9 per cent of these organs: D. lanceatum--16.3 per cent; Ech. granulosus--7.1 per cent; F. hepatica--3.5 per cent. Cysticercus tenuicollis was established in 1.7 per cent of the cases. Worm-free were only 5.2 per cent of the livers. In decending order the parasite burden ranked as followes: Ech. granulosus, D. lanceatum, F. hepatica, Cyst. tenuicollis.
Helminthiasis, Animal , Liver/parasitology , Sheep Diseases/parasitology , Abattoirs , Animals , Bulgaria , Liver/pathology , Sheep , Sheep Diseases/pathology
A total of 55726 Ixodes ticks were collected from farm and wild animals on the territory of Bourgas district in the 1958-1964 period and were specifically differentiated. At a later study in the region of the town of Michourin other 26722 ticks were collected from sheep. A total of 15 species were determined. It was found that Ixodes ricinus in the East Balkan Mountain to the north of the town of Nessebur develops after a three-year pattern in pure populations of larvae, nymphs, and imagoes, the peak periods being autumn and spring. The tick-induced paralyses in sheep and goats in this region were due to I. ricinus. A year-round occurrence was established of ticks of the H. plumbeum, I. ricinus, H. punctata, and R. bursa species parasitising in animals. The Ixodes fauna in the Michourin region, where the pastures in 1971 were grazed only by sheep, shows the following trends: H. punctata and R. turanicus ticks, which are preferably parasitising in sheep, increase their relative share. R. bursa, D. marginatus and I. ricinus, which, besides sheep, have also other hosts among farm animals, have lowered their relative share, however, still remain at a comparatively high level. No further decrease is expected in this respect. The H. plumbeum species occurs less frequently, and its level may drop further or remain as it is now. H. inermis has strongly decreased in numbers. It is expected, however, to persist at the present level. B calcaratus has not been found in sheep in the Michourin region. Maybe sporadic cases in single sheep would not be an exception provided it parasitises in wild animals (does).
Ticks , Animals , Bulgaria , Larva , Nymph , Seasons , Sheep , Ticks/classification , Time Factors
