954 resultados para Parallax--Stars


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The Lofoten-Vesterålen marine shelf is one of the most geologically diverse coast and offshore margin areas in Norway. This leads to huge heterogeneity in marine environments, and often high biodiversity. However, little is known yet about the benthic communities in this region. Within the ARCTOS LoVe MarineEco project the epibenthic communities of the Hola trough (Vesterålen) are analysed to give a first description of their spatial distribution. In this trough both a complex hydrodynamic system and varied topographic submarine elements occur. Trawling samples were collected for two different approaches: one in a meso-scale and another in a small-scale. For the broad scale a transect consisting in three stations was developed, while for the fine scale a small area on a sand wave field, consisting in five stations called HolaBox, was sampled. All organisms were intended to be identified to species level and colonial fauna was discarded for the analysis. Different diversity indexes were assessed (Shannon index (H’) and Pielou’s eveness (J’)). Clustering and nMDS analyses identified four statistically significant groups in terms of abundance (ind./100m2). A total amount of 211 different taxa were found within all stations. The more outer part of the transect (close to the shelf edge) presented a huge abundance of organisms and was dominated by the hemi sessile tube-builder polychaetes Nothria conchylega and Eunice dubitata and the sea urchin Gacilechinus acutus, while the more inner parts presented less abundance of individuals. Probably some upwelling produced by the Norwegian Atlantic Current (NWAC) is influencing the shelf edge increasing the primary production and, therefore, enriching the seafloor in this region. The sand wave field presented two different groups with few amount of individuals. Small-scale variability could be produced by the high heterogeneity within the different types of sand waves, while the scarce abundance of animals can be produced by the permanent changing environment that movable sand waves produce. Here more active and mobile fauna was found such as brittle stars and hermit crabs (among others). Finally, a fourth group was found in the most inner station of the transect, laying on a ridge in the central part of the trough. This station, with coarse substrate, was mainly dominated again by brittle stars and sea urchins. We can conclude that this is a really heterogeneous trough in environments and therefore in communities (even in a local scale). More detailed studies that focus in the local environmental drivers have to be carried out to get an integrated understanding of the structure of benthic communities in this system.

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Context. Since its launch, the X-ray and γ-ray observatory INTEGRAL satellite has revealed a new class of high-mass X-ray binaries (HMXB) displaying fast flares and hosting supergiant companion stars. Optical and infrared (OIR) observations in a multi-wavelength context are essential to understand the nature and evolution of these newly discovered celestial objects. Aims. The goal of this multiwavelength study (from ultraviolet to infrared) is to characterise the properties of IGR J16465−4507, to confirm its HMXB nature and that it hosts a supergiant star. Methods. We analysed all OIR, photometric and spectroscopic observations taken on this source, carried out at ESO facilities. Results. Using spectroscopic data, we constrained the spectral type of the companion star between B0.5 and B1 Ib, settling the debate on the true nature of this source. We measured a high rotation velocity of v = 320 ± 8km s-1 from fitting absorption and emission lines in a stellar spectral model. We then built a spectral energy distribution from photometric observations to evaluate the origin of the different components radiating at each energy range. Conclusions. We finally show that, having accurately determined the spectral type of the early-B supergiant in IGR J16465−4507, we firmly support its classification as an intermediate supergiant fast X-ray transient (SFXT).

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Draft of a one-page letter regarding Croswell's maps of the stars.

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This heavily illustrated notebook contains entries on the following topics, among others: geography; mensuration; navigation and the history of navigation; "the use of Gunter's Scale in plain sailing;" compasses; quadrants and their use; "the refraction of the stars observed by the famous Tycho Brahe;" the latitude and longitude of coasts in America, Europe, and Africa; oceans and islands; mountains and "burning mountains" (volcanoes); rivers and lakes; forests and deserts; maps and sea charts; and the uses of geometry and other measurements by carpenters, joiners, painters, glaziers, masons, and bricklayers. Many pages contain navigational problems and their detailed solutions, as well as chronologies of global exploration and lists of all known rivers, mountains, and other geographic features across the world, many with vivid descriptions. The last pages of the notebook contain entries made in December of 1743 regarding celestial measurements Prince took in Stratford, Connecticut, where he was staying with his brother.

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Poetry on astrological significance of each day depending on positions of stars and times of day when various stars exert their influence. Arranged according to days and hours of appearance of each star.

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"September 1989"--Cover.

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Signed: C.C. Kiess.

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At head of title: Don't lose your way at night.

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First line (3rd song): Oh, little blue lady!

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Includes bibliographical references and indexes.

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Includes earlier editions of each volume.

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[no. 1]. The birth of the Red Cross -- [no. 2]. Human interest guaranteed -- [no. 3]. Tornado! -- [no. 4]. The Red Cross reports -- [no. 5]. Headlines to come -- [no. 6]. The Texas famine -- [no. 7]. The stars and stripes forever -- [no. 8]. Death on the highway -- [no. 9]. Junior and his dad -- [no. 10]. Eyes for the sightless.