1207 research outputs found
Sort by
‘Hij Die Niet Leest Is Een Dweil’: Nieuw Licht Op de Commentaartraditie van de Félire Óengusso.
Get PDFUnaccusativity and the subject pronoun in Middle and Early Modern Irish
Get PDFThis article examines Middle and Early Modern Irish sentences like /in mairenn hé/? ‘does he live?’ and /do-chádar d’éag uile iad/ ‘they all died’ in which the subject pronoun has the form normally associated with the subject of a passive-impersonal verb or the direct object of a transitive verb. References to this construction in the Classical Modern Irish grammatical tracts are discussed first, Middle and Early Modern Irish examples are then presented, and their syntax and semantics are investigated. It is argued that the subject in these sentences is not the semantic agent and that this motivates the use of these pronominal forms. This construction is then placed in a wider typological context. Finally, attention is drawn to a possible precursor construction in which the subject pronoun takes the form of an infix
Review of N. Mac Cathmhaoil, M. Nic Cathmhaoil and C. Mac Seáin (eds), Súgán an Dúchais: aistí ar ghnéithe de thraidisiún liteartha Chúige Uladh i gcuimhne ar Dhiarmaid Ó Doibhlin (Derry/Londonderry, 2019)
Get PDF
A Descriptive Catalogue of TCD MS H.3.18 (1337), vols 2-4, pp. 1-87: 'Máel Íosa's Book'
Get PDF‘Máel Íosa’s book’ consists of some eighty-seven pages bound into the composite volume TCD MS H 3. 18 (1337). It was compiled by Máel Íosa, who was assisted by several other scribes, at various locations, in the early 1500s. It is an invaluable medieval miscellany that contains numerous legal texts and glossaries, as well as texts of poetic, pseudo-historical, religious, or medical subject matter, among others, and many marginalia. ‘Máel Íosa’s book’ was inadequately described in the Catalogue of the Irish Manuscripts in the Library of Trinity College, Dublin (1921). This article presents a detailed descriptive catalogue of the codicological aspects and textual contents of this book
An extreme particle accelerator in the Galactic plane: HESS J1826−130
Get PDFThe unidentified very-high-energy (VHE; E > 0.1 TeV) γ-ray source, HESS J1826-130, was discovered with the High Energy Stereoscopic System (HESS) in the Galactic plane. The analysis of 215 h of HESS data has revealed a steady γ-ray flux from HESS J1826-130, which appears extended with a half-width of 0.21° ± 0.02stat° ± 0.05sys°. The source spectrum is best fit with either a power-law function with a spectral index Γ = 1.78 ± 0.10stat ± 0.20sys and an exponential cut-off at 15.2-3.2+5.5 TeV, or a broken power-law with Γ1 = 1.96 ± 0.06stat ± 0.20sys, Γ2 = 3.59 ± 0.69stat ± 0.20sys for energies below and above Ebr = 11.2 ± 2.7 TeV, respectively. The VHE flux from HESS J1826-130 is contaminated by the extended emission of the bright, nearby pulsar wind nebula, HESS J1825-137, particularly at the low end of the energy spectrum. Leptonic scenarios for the origin of HESS J1826-130 VHE emission related to PSR J1826-1256 are confronted by our spectral and morphological analysis. In a hadronic framework, taking into account the properties of dense gas regions surrounding HESS J1826-130, the source spectrum would imply an astrophysical object capable of accelerating the parent particle population up to ≳200 TeV. Our results are also discussed in a multiwavelength context, accounting for both the presence of nearby supernova remnants, molecular clouds, and counterparts detected in radio, X-rays, and TeV energies
Detection of very-high-energy gamma-ray emission from the colliding wind binary Eta Car with H.E.S.S.
Get PDFAims. Colliding wind binary systems have long been suspected to be high-energy (HE; 100 MeV 100 GeV) γ-ray emission from η Car around the last periastron passage in 2014 with the ground-based High Energy Stereoscopic System (H.E.S.S.).
Methods. The region around η Car was observed with H.E.S.S. between orbital phase p = 0.78−1.10, with a closer sampling at p ≈ 0.95 and p ≈ 1.10 (assuming a period of 2023 days). Optimised hardware settings as well as adjustments to the data reduction, reconstruction, and signal selection were needed to suppress and take into account the strong, extended, and inhomogeneous night sky background (NSB) in the η Car field of view. Tailored run-wise Monte-Carlo simulations (RWS) were required to accurately treat the additional noise from NSB photons in the instrument response functions.
Results. H.E.S.S. detected VHE γ-ray emission from the direction of η Car shortly before and after the minimum in the X-ray light-curve close to periastron. Using the point spread function provided by RWS, the reconstructed signal is point-like and the spectrum is best described by a power law. The overall flux and spectral index in VHE γ rays agree within statistical and systematic errors before and after periastron. The γ-ray spectrum extends up to at least ~400 GeV. This implies a maximum magnetic field in a leptonic scenario in the emission region of 0.5 Gauss. No indication for phase-locked flux variations is detected in the H.E.S.S. data
CMEs in the Heliosphere: III. A Statistical Analysis of the Kinematic Properties Derived from Stereoscopic Geometrical Modelling Techniques Applied to CMEs Detected in the Heliosphere from 2008 to 2014 by STEREO/HI-1
Get PDFWe present an analysis of coronal mass ejections (CMEs) observed by the Heliospheric Imagers (HIs) onboard NASA’s Solar Terrestrial Relations Observatory (STEREO) spacecraft. Between August 2008 and April 2014 we identify 273 CMEs that are observed simultaneously, by the HIs on both spacecraft. For each CME, we track the observed leading edge, as a function of time, from both vantage points, and apply the Stereoscopic Self-Similar Expansion (SSSE) technique to infer their propagation throughout the inner heliosphere. The technique is unable to accurately locate CMEs when their observed leading edge passes between the spacecraft; however, we are able to successfully apply the technique to 151, most of which occur once the spacecraft-separation angle exceeds 180, during solar maximum. We find that using a small half-width to fit the CME can result in inferred acceleration to unphysically high velocities and that using a larger half-width can fail to accurately locate the CMEs close to the Sun because the method does not account for CME over-expansion in this region. Observed velocities from SSSE are found to agree well with single-spacecraft (SSEF) analysis techniques applied to the same events. CME propagation directions derived from SSSE and SSEF analysis agree poorly because of known limitations present in the latter
The Spectrometer/Telescope for Imaging X-rays (STIX)
Get PDFAims. The Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter is a hard X-ray imaging spectrometer, which covers the energy range from 4 to 150 keV. STIX observes hard X-ray bremsstrahlung emissions from solar flares and therefore provides diagnostics of the hottest (⪆10 MK) flare plasma while quantifying the location, spectrum, and energy content of flare-accelerated nonthermal electrons.
Methods. To accomplish this, STIX applies an indirect bigrid Fourier imaging technique using a set of tungsten grids (at pitches from 0.038 to 1 mm) in front of 32 coarsely pixelated CdTe detectors to provide information on angular scales from 7 to 180 arcsec with 1 keV energy resolution (at 6 keV). The imaging concept of STIX has intrinsically low telemetry and it is therefore well-suited to the limited resources available to the Solar Orbiter payload. To further reduce the downlinked data volume, STIX data are binned on board into 32 selectable energy bins and dynamically-adjusted time bins with a typical duration of 1 s during flares.
Results. Through hard X-ray diagnostics, STIX provides critical information for understanding the acceleration of electrons at the Sun and their transport into interplanetary space and for determining the magnetic connection of Solar Orbiter back to the Sun. In this way, STIX serves to link Solar Orbiter’s remote and in-situ measurements
