Formation of kinematic subsystems in stellar spiral-spiral mergers

[EN]We show that kinematically peculiar cores may be generated in stellar spiral-spiral mergers. Kinematic segregation appears as the central bulges transport orbital angular momentum inward to the center of the remnant, while the outer parts keep the spin signature of the precursor disks. The peculiar core is composed mostly of bulge material, and its size best matches that of observed peculiar cores for mergers with unequal galaxy masses (~2:1). Population decoupling is predicted by the rapid radial decrease of the bulge fraction in the remnant. In this scenario, a starburst may pump up the remnant metallicity, but otherwise the high metallicity of the kinematically decoupled core is built on the high metal content of the inner bulges rather than on a high selfenrichment of a population built from scratch out of the precursors’ gas. Mergers with galaxy mass ratios 3:1 and above generate disk galaxies with counterrotating bulges.Peer reviewe

From hagiography to celtic cosmology: archaeoastronomy and christian landscape in ourense (nw spain)

The cult of Santa Mariña is very popular in the region of Galicia, in northwest Spain. According to tradition, she was born and martyred in two sites at the heart of the modern-day province of Ourense: she was born and grew up around the lagoon of Antela, and was martyred in the parish of Santa Mariña de Augas Santas, where she performed miracles and where her tomb is still preserved. Both places are located in the territory of the Limici, a pre-Roman Celtic tribe, and contain a remarkable amount of archaeological material from the Iron Age and Roman times. An archaeoastronomical study has revealed that the most important archaeological sites have a number of significant solar and lunar relationships attributable to the Celtic tradition (lunistices, Celtic mid-season festivals, the cosmos divided into three levels). Christianity preserved these structures through the feast dates of the saints worshipped in different parishes and other places, and their arrangement in different local landscapes. Episodes of Mariña‟s life and her places of worship are important because they coincide with significant points in the astronomical alignments that have been detected. Hydatius of Chaves (c. 400-469) a Limici scholar, bishop and author of a Chronicle, is considered responsible for introducing the cult of Santa Mariña, and as the driving force behind the Christianization of a landscape/ skyscape that was previously defined by a Celtic worldviewS

Roman or gaulic: orientation as a footprint of cultural identity?

The towns of Aventicum (Avenches, Switzerland) and Augusta Raurica (Augst, Switzerland) were the main Roman towns of the Civitas Helvetiorum in the province of Gallia Belgica (and later shifted to Germania Superior). Both were probably founded ex–nihilo, the first at the time of Claudius (mid first century AD), the second by Caius Munatius Plancus around 44 BC and was refounded soon after the 15 BC . The layout of both towns conforms to all Roman standards with an urban grid in orthogonal shape and with several public buildings to hail the splendor of Roman society. Also the orientation of such grid seems to conform to most Roman standards. The archaeoastronomical study of both towns is contextualised following two paths. Firstly, we consider the orientation of the layout of some other regional Roman foundations as Vesontio (Besançon, France), Iulia Equestris (Nyon, Switzerland), Forum Claudii (Martigny, Switzerland), and Vindonissa (Windisch, Switzerland). Secondly, we realize that the sacred areas (including temples, sanctuaries and often theaters) of this two towns seem to break the general layout in both of them: these appear to bear orientations skewed several degrees with respect to the general grid. In both cases a Roman theater seems to feature some kind of relation with the temple as in other areas in the Roman Empire. Notably, the orientation of these temples share similarities to other sacred precincts in the region possibly built prior to the Roman conquest. This duality in orientations, with a grid with an orientation different to that of some of the main public buildings may be a witness to a period when a compromise, negotiation, or resistance either implicit or explicit, took place between conquered and conquerors. Interestingly, similar cases have recently been reported in the Roman towns of Augusta Treverorum (present day Trier, Germany) or Augustodum (modern day Autun, France)S

The Rock sanctuary of Baroña Hill Fort as an exchanger, interface and cross-roads among the world layers of celtic cosmology

The small Iron-Age hillfort of Baroña (Porto do Son, A Coruña, Galicia, Spain) was inhabited during the last centuries BC and is in a singularly hostile environment on a small peninsula facing the Atlantic Ocean at the western end of the Muros-Noia estuary. The habitat is composed by a mere twenty houses defended by a stunning complex of three lines of massive walls. A large rocky acropolis with faint but clear signs of human activity hangs over the habitat. The study of the acropolis reveals the possibility that they include awareness of the surrounding landscape and relevant moments of the solar cycle. A monumental stairway adjacent to the acropolis leads towards the cliff overlooking the sea and seems aligned with the winter solstice sunset happening on the ocean beyond. Over the acropolis, the rock that dominates the area presents carved basins and slender petroglyphs related with winter and summer solstice sunrises while the eastern horizon is dominated by Mount Enxa that signals 1st May sunrise as seen from the acropolis. Finally, summer solstice sunrise seen from the acropolis coincides with a little hill some 2.5 kilometer away on which slope a panel with petroglyphs presents the only carved representation of the sun known in Galicia and the panel itself is related to some astral calendric relations. We argue that the hillfort‟s location seems to be a special place chosen to be a cross-road between the sky, the land, and the sea, i.e. the three elements constituting the Cosmos according to the Celtic tradition and shared by other Indo-European traditionsS

The Churches of Santiago de Compostela, a diachronic analysis of their orientations

The orientation of nearly 50 churches in the historic city of Santiago de Compostela are presented. These include churches built along the history of the town, from the early Medieval period until the end of the 20thcentury. Interestingly, all churches built before the Council of Trent appear to have orientations consistent with canonical prescriptions, notably in two flavors. One would be consistent with the canonical equinox at the date of construction, possibly dictated by the orientation of the Cathedral itself. The other orientation is set a few degrees south of due east and could be dictated by the streets of the Medieval town. After the Council of Trent churches were built mostly to have the façade perpendicular to a main street, so that the apse and the altar no longer are systematically facing towards the rising sun

Semantics-supported cooperative learning for enhanced awareness

Awareness is required for supporting all forms of cooperation. In Computer Supported Collaborative Learning (CSCL), awareness can be used for enhancing collaborative opportunities across physical distances and in computer-mediated environments. Shared Knowledge Awareness (SKA) intends to increase the perception about the shared knowledge, students have in a collaborative learning scenario and also concerns the understanding that this group has about it. However, it is very difficult to produce accurate awareness indicators based on informal message exchange among the participants. Therefore, we propose a semantic system for cooperation that makes use of formal methods for knowledge representation based on semantic web technologies. From these semantics-enhanced repository and messages, it could be easier to compute more accurate awareness

Arqueoastronomía, antropología y paisaje

En el presente artículo intentaremos mostrar la profunda conexión que existe entre las arqueologías del espacio y la arqueoastronomía. Para que esta conexión no se limite a una declaración de intenciones es preciso mostrar los fundamentos y posibilidades de ambas perspectivas disciplinares y metodológicas teniendo en cuenta, sobre todo, que ambas son diversas en sus respectivas trayectorias. En este contexto se plantea que la antropología histórica puede ser útil como orientación disciplinar capaz de matizar el peso creciente de tecnologías analíticas complejas (como puede ser el énfasis en el uso de modelos celestes en arqueoastronomía), que marca el riesgo de la construcción de un ámbito de conocimiento autoreferenciado, que no aporte gran cosa a la caracterización de las formas culturales del pasado. De este modo se mostrará cómo las diversas orientaciones disciplinares deben entenderse siempre como destinadas a comprender cada vez mejor aspectos de la vida de las sociedades pretéritas que, de otra manera, permanecerían incógnitos.An essay is made to emphasize the deep relationships connecting archaeoastronomy and landscape archaeology. To assert these connections it is essential to go beyond mere verbal statements, demonstrating the foundations and possibilities of both approaches, bearing in mind that they are clearly distinct in their historical trajectories. In this context, it is suggested that historical anthropology can be useful as a disciplinary guide in order to compensate the growing influence of complex technicalities, such as the use of astronomic models in archaeoastronomy that risk to get only auto-referential knowledge without much connections with past cultural forms. Our final aim is to characterize these disciplinary approaches as a means to an increasingly better understanding of life aspects in ancient societies that otherwise would remain unknown

Landscape construction and time reckoning in Iron Age Celtic Iberia

In this paper, we report on three areas of the Iberian Peninsula that were occupied at least during the Iron Age and the early stages of Romanisation, where observations of astronomical phenomena in the landscape, rock carvings, and Latin inscriptions point to a particular method of time reckoning. All of these sites have previously been connected with the Celtic culture. The knowledge of the natural world that Classical sources assigned to these peoples need not have been reflected in a monolithic calendrical system used by all Celtic communities on the Continent. In fact, such a ‘Celtic calendar’ may have had different expressions in different areas, expressed in different ways, although sharing some common characteristics such as the particual use of the lunar and solar cycles.V članku poročamo o treh območjih na Iberskem polotoku, ki so bila poseljena vsaj od železne dobe in začetka romanizacije, kjer smo na podlagi opazovanj astronomskih fenomenov v pokrajini, na podlagi skalnih rezbarij in latinskih napisov prepoznali posebno metodo merjenja časa. Vsa predstavljena najdišča so bila doslej povezana s keltsko kulturo. Znanje o naravi in svetu, ki so ga klasični viri pripisali Keltom, se ni nujno odražalo v monolitskem koledarskem sistemu, ki so ga uporabljale vse keltske skupnosti na celini. Takšen ‘keltski koledar’ se je lahko v različnih območjih izražal na drugačne načine, vendar je pri tem ohranil nekatere skupne značilnosti, kot je npr. posebna uporaba Luninih in Sončevih ciklov

Evolution induced by dry minor mergers onto fast-rotator S0 galaxies

Tapia, Trinidad et al.[Context] Numerical studies have shown that the properties of the S0 galaxies with kinematics intermediate between fast and slow rotators are difficult to explain by a scenario of major mergers.[Aims] We investigate whether the smoother perturbation induced by minor mergers can reproduce these systems.[Methods] We analysed collisionless N-body simulations of intermediate and minor dry mergers onto S0s to determine the structural and kinematic evolution induced by the encounters. The original primary galaxies represent gas-poor fast-rotator S0b and S0c galaxies with high intrinsic ellipticities. The original bulges are intrinsically spherical and have low rotation. Different mass ratios, parent bulges, density ratios, and orbits were studied.[Results] Minor mergers induce a lower decrease of the global rotational support (as provided by λe) than encounters of lower mass ratios, which results in S0s with properties intermediate between fast and slow rotators. The resulting remnants are intrinsically more triaxial, less flattened, and span the whole range of apparent ellipticities up to εe ∼ 0.8. They do not show lower apparent ellipticities in random projections than initially; on the contrary, the formation of oval distortions and the disc thickening increase the percentage of projections at 0.4 0.9), but exhibit a wide range of triaxialities (0.20 < T < 1.00). In the plane of global anisotropy of velocities (δ) vs.? intrinsic ellipticity (εe,intr), some of our models extend the linear trend found in previous major merger simulations towards higher ε e,intr values, while others clearly depart from it (depending on the progenitor S0). This is consistent with the wide dispersion exhibited by real S0s in this diagram compared with ellipticals, which follow the linear trend drawn by major merger simulations.[Conclusions] The smoother changes induced by minor mergers can explain the existence of S0s with intermediate kinematic properties between fast and slow rotators that are difficult to explain with major mergers. The different trends exhibited by ellipticals and S0 galaxies in the δ - εe diagram may be pointing to the different role played by major mergers in the build-up of each morphological type. © ESO 2014.Supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under projects AYA2006-12955, AYA2009-10368, AYA2009-11137, AYA2012- 30717, AYA2010-21322-C03-02, AYA2010-21887-C04-04, and by the Madrid Regional Government through the AstroMadrid Project (CAM S2009/ESP-1496, http://www.laeff.cab.inta-csic.es/projects/astromadrid/main/index.php). Funded by the Spanish MICINN under the Consolider-Ingenio 2010 Program grant CSD2006- 0070: “First Science with the GTC” (http://www.iac.es/consolider-ingenio-gtc/), and by the Spanish programme of International Campus of Excellence Moncloa (CEI). A.C.G.G. is a Ramón y Cajal Fellow of the Spanish MINECO.Peer Reviewe

Las orientaciones de las iglesias de Ibiza y Formentera (Baleares, España)

Las iglesias son elementos conspicuos y característicos del paisaje de Ibiza y Formentera tanto en las ciudades como en el campo. De hecho, y hasta hace relativamente poco tiempo, eran uno de los elementos vertebradores del paisaje pitiuso. El estudio de sus orientaciones permite identificar varios fenómenos culturales interesantes. Es posible que algunas de las iglesias más antiguas, construidas pocas décadas tras la conquista cristiana, reflejen orientaciones de edificaciones anteriores, notablemente mezquitas. Además, el estudio de la orientación de las iglesias erigidas de forma intensiva durante el siglo XVIII permite distinguir dos hechos destacables. Por un lado, la división de la isla en dos sectores. El norte con orientaciones de las iglesias que siguen los preceptos canónicos, y un sector sur, con orientaciones cercanas a la línea meridiana. Posiblemente esta división en el sur venga motivada por la necesidad de construir las iglesias cerca de las vías de tránsito que facilitasen su entrada al usarse como espacios de refugio frente a los frecuentes ataques berberiscos. Por otro lado, se identifica el posible uso de métodos magnéticos para obtener la orientación de estas iglesias.The landscape of Ibiza and Formentera is characterized by the conspicuous churches both in cities and in the fields. Until relatively recent times they were one of the main elements that created the insular landscape. The study of their orientation allows to identify several interesting phenomena. It is possible that some of the oldest churches, built a few decades after the Christian conquest, reflect orientations of previous buildings, notably mosques. In addition, the study of the churches intensively built during the XVIIIth century identifies two notable phenomena. On the one hand, the division of the island into two sectors. The north one, with orientations of the churches that follow the canonical precepts, and a southern sector, with orientations close to the meridian line. Possibly this division in the south is motivated by the need to build churches near the transit routes to facilitate their entry when used as spaces of refuge against the frequent Berber attacks. On the other hand, we identify the possible use of magnetic methods to obtain the orientation of these churches.Sociedad Interamericana de Astronomía en la Cultur