Extreme magnification of an individual star at redshift 1.5 by a galaxy-cluster lens

Galaxy-cluster gravitational lenses can magnify background galaxies by a total factor of up to ~50. Here we report an image of an individual star at redshift z = 1.49 (dubbed MACS J1149 Lensed Star 1) magnified by more than ×2,000. A separate image, detected briefly 0.26″ from Lensed Star 1, is probably a counterimage of the first star demagnified for multiple years by an object of ≳3 solar masses in the cluster. For reasonable assumptions about the lensing system, microlensing fluctuations in the stars’ light curves can yield evidence about the mass function of intracluster stars and compact objects, including binary fractions and specific stellar evolution and supernova models. Dark-matter subhaloes or massive compact objects may help to account for the two images’ long-term brightness ratio

The European Solar Telescope

The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l'Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems

A simultaneous search for High-z LAEs and LBGs in the SHARDS survey

We have undertaken a comprehensive search for both Lyman Alpha Emitters (LAEs) and Lyman Break Galaxies (LBGs) in the SHARDS Survey of the GOODS-N field. SHARDS is a deep imaging survey, made with the 10.4 m Gran Telescopio Canarias (GTC), employing 25 medium band filters in the range from 500 to 941 nm. This is the first time that both LAEs and LBGs are surveyed simultaneously in a systematic way in a large field. We draw a sample of 1558 sources; 528 of them are LAEs. Most of the sources (1434) show rest-frame UV continua. A minority of them (124) are pure LAEs with virtually no continuum detected in SHARDS. We study these sources from z ∼ 3.35 up to z ∼ 6.8, well into the epoch of reionization. Note that surveys done with just one or two narrow band filters lack the possibility to spot the rest-frame UV continuum present in most of our LAEs. We derive redshifts, Star Formation Rates (SFRs), Lyα Equivalent Widths (EWs) and Luminosity Functions (LFs). Grouping within our sample is also studied, finding 92 pairs or groups of galaxies at the same redshift separated by less than 60 comoving kpc. In addition, we relate 87 and 55 UV-selected objects with two known overdensities at z = 4.05 and z = 5.198, respectively. Finally, we show that surveys made with broad band filters are prone to introduce many unwanted sources (∼20% interlopers), which means that previous studies may be overestimating the calculated LFs, specially at the faint end

The spread of agriculture in northern Iberia: new archaeobotanical data from El Mirón cave (Cantabria) and the open-air site of Los Cascajos (Navarra)

This paper presents archaeobotanical results from the Neolithic levels (5,300–4,000 b.c.) of two recently excavated sites in northern Iberia: El Mirón cave (Cantabria) and the open-air site of Los Cascajos (Navarra). A cereal grain from El Mirón is currently the earliest domesticated plant remain from this region. Despite the large number of samples examined, plant remains are few. They include basically cereals (Triticum monococcum, T. dicoccum, T. aestivum/durum/turgidum and Hordeum vulgare) and some nuts and fruits (Corylus avellana, Quercus sp., Vitis sp., etc.). The presence of free-threshing wheats at El Mirón opens up an interesting subject for debate, as until now naked wheats have been absent from the early Neolithic archaeobotanical record of the coastal Cantabrian region. Hulled wheat chaff is the main plant component from Los Cascajos, south of the Cantabrian Cordillera in Navarra, indicating waste from processing activities. The association of barley almost exclusively with both a burial and a ritual vase in Los Cascajos could be related specific rituals or ceremonies.Excavations at El Mirón Cave, directed by Straus and González Morales since 1996, have been funded by the Fundación M. Botín, the U.S. National Science Foundation, the National Geographic Society, the L.S.B. Leakey Foundation, the Gobierno de Cantabria and the University of New Mexico. Excavations at Los Cascajos, directed by J. García Gazólaz and J. Sesma Sesma, have been funded by the Gobierno de Navarra. L. Peña-Chocarro has worked with a post-doctoral contract within the I3P Program, funded by the European Social Fund. L. Zapata’s study was done under a postdoctoral research grant from the Basque Government (Ref. BFI01.12) as part of the Research Group of the University of the Basque Country, UPV/EHU 9/UPV00155.130-14570/2002.Peer reviewe