Search results for "ODS"
showing 10 items of 5812 documents
Gravitational wave signature of proto-neutron star convection: I. MHD numerical simulations
2021
Gravitational waves provide a unique and powerful opportunity to constrain the dynamics in the interior of proto-neutron stars during core collapse supernovae. Convective motions play an important role in generating neutron stars magnetic fields, which could explain magnetar formation in the presence of fast rotation. We compute the gravitational wave emission from proto-neutron star convection and its associated dynamo, by post-processing three-dimensional MHD simulations of a model restricted to the convective zone in the anelastic approximation. We consider two different proto-neutron star structures representative of early times (with a convective layer) and late times (when the star is…
First M87 Event Horizon Telescope Results. III. Data Processing and Calibration
2019
We present the calibration and reduction of Event Horizon Telescope (EHT) 1.3 mm radio wavelength observations of the supermassive black hole candidate at the center of the radio galaxy M87 and the quasar 3C 279, taken during the 2017 April 5–11 observing campaign. These global very long baseline interferometric observations include for the first time the highly sensitive Atacama Large Millimeter/submillimeter Array (ALMA); reaching an angular resolution of 25 μas, with characteristic sensitivity limits of ~1 mJy on baselines to ALMA and ~10 mJy on other baselines. The observations present challenges for existing data processing tools, arising from the rapid atmospheric phase fluctuations, …
First M87 Event Horizon Telescope Results. II. Array and Instrumentation
2019
The Event Horizon Telescope (EHT) is a very long baseline interferometry (VLBI) array that comprises millimeter- and submillimeter-wavelength telescopes separated by distances comparable to the diameter of the Earth. At a nominal operating wavelength of ~1.3 mm, EHT angular resolution (λ/D) is ~25 μas, which is sufficient to resolve nearby supermassive black hole candidates on spatial and temporal scales that correspond to their event horizons. With this capability, the EHT scientific goals are to probe general relativistic effects in the strong-field regime and to study accretion and relativistic jet formation near the black hole boundary. In this Letter we describe the system design of th…
Time domain astronomy with the THESEUS satellite
2021
THESEUS is a medium size space mission of the European Space Agency, currently under evaluation for a possible launch in 2032. Its main objectives are to investigate the early Universe through the observation of gamma-ray bursts and to study the gravitational waves electromagnetic counterparts and neutrino events. On the other hand, its instruments, which include a wide field of view X-ray (0.3-5 keV) telescope based on lobster-eye focussing optics and a gamma-ray spectrometer with imaging capabilities in the 2-150 keV range, are also ideal for carrying out unprecedented studies in time domain astrophysics. In addition, the presence onboard of a 70 cm near infrared telescope will allow simu…
The response of flood-plain ecosystems to the Late Glacial and Early Holocene hydrological changes: A case study from a small Central European river …
2016
Abstract We use a range of environmental variables to explore the possible drivers influencing the biota, especially the composition of aquatic invertebrates, during the Younger Dryas (YD) and Early Holocene (EH) in different river valley sites: a well-developed meandering river and the confluence zone of headwater streams. Using pollen, macrofossil, cladoceran, and chironomid as well as geochemical and lithological data as proxies for environmental factors (i.e., water depth and temperature), we attempt to show that these different sites display similar hydroclimatic signals (especially floods). The geochemical records in the studied valley are correlated with environmental factors, such a…
Isotopic Anthropology of Rural German Medieval Diet: Intra- and Inter-population Variability
2016
This study investigates the diet of an eleventh century CE parish community located in northwestern Germany. We assessed the isotopic compositions of human (n = 24) and faunal (n = 17) bone collagen (δ 13Ccol, δ 15Ncol) and human structural carbonate (δ 13Csc) using skeletal material recovered from the Dalheim cemetery. Traditional interpretation of the isotopic data indicates that Dalheim residents likely relied on a C3 plant-based diet and consumed some terrestrial animal products without evidence of marine resource input in the diet. Bivariate and multivariate models used as an additional means to assess diet indicate minor consumption of C4 plant foods in this community. The multivariat…
Aqua Mater: On the Meaning of the Theonym Betatun
2021
La aparición en el entorno del santuario tardoibérico de Las Atalayuelas (Fuerte del Rey – Torredelcampo, Jaén) de una inscripción en la que se documenta el teónimo ibérico Betatun abre nuevas perspectivas en el estudio de la religión ibérica. Con el presente artículo intentamos demostrar que en el nombre de la divinidad está implícito un elemento común que lo relacionaría con una serie de topónimos e hidrónimos, tanto antiguos como modernos, y que no es otro que el agua. The finding of an inscription containing the Iberian theonym Betatun in the surrounding area of the Late Iberian sanctuary in Las Atalayuelas site (Fuerte del Rey – Torredelcampo, Jaén) opens up new perspectives for the st…
El yacimiento calcolítico de Karea en el contexto de las cuevas sepulcrales de Gipuzkoa (País Vasco)
2018
En el yacimiento arqueológico de Karea (Aia, Gipuzkoa), integrado por las cavidades contiguas de Karea-A y Karea-B, se recuperaron numerosos restos cerámicos y faunísticos (Karea-A) y vestigios de una inhumación calcolítica (Karea-B). El presente trabajo se ha vertebrado en dos ejes. En primer lugar, el estudio de ambos depósitos mediante diferentes disciplinas: (1) estudio antropológico; (2) estudio del ajuar, compuesto por restos cerámicos y faunísticos; (3) identificación antracológica de los restos leñosos recuperados en el depósito funerario y por último, (4) estudios isotópicos que nos han permitido obtener datos de la alimentación (δ13C y δ15N) y procedencia (87Sr/86Sr) del sujeto in…
The stable isotope composition of organic and inorganic fossils in lake sediment records: current understanding, challenges, and future directions
2018
This paper provides an overview of stable isotope analysis (H, C, N, O, Si) of the macro- and microscopic remains from aquatic organisms found in lake sediment records and their application in (palaeo)environmental science. Aquatic organisms, including diatoms, macrophytes, invertebrates, and fish, can produce sufficiently robust remains that preserve well as fossils and can be identified in lake sediment records. Stable isotope analyses of these remains can then provide valuable insights into habitat-specific biogeochemistry, feeding ecology, but also on climatic and hydrological changes in and around lakes. Since these analyses focus on the remains of known and identified organisms, they …
Climbing into the past—first Himalayan mummies discovered in Nepal
2003
In a cave system in Mebrak (Mustang District, Western Nepal), a team of archaeologists investigating extensive abandoned settlements in the high Himalayas made an extraordinary discovery in 1995. One of the caves had been used as a community burial chamber from ca. 400 BC to 50 AD. Inside, approximately 30 naturally mummified bodies rested in bed-like wooden coffins exhibiting ornamental carving and elaborate painting. The dead had been furnished with a rich store of grave goods consisting of both personal ornaments and objects of daily life as well as the remains of domestic animals. Due to the favourable climatic conditions, all of the artefacts, which also include fur and textile garment…