Search results for "CLIP"

Resolving the Fe xx v Triplet with Chan d r a in Centaurus X-3

2005

We present the results of a 45 ks Chandra observation of the high-mass X-ray binary Cen X-3 at orbital phases between 0.13 and 0.40 (in the eclipse post-egress phases). Here we concentrate on the study of discrete features in the energy spectrum at energies between 6 and 7 keV, that is, on the iron Kα line region, using the High Energy Transmission Grating Spectrometer (HETGS) on board the Chandra satellite. We clearly see a Kα neutral iron line at ~6.40 keV and were able to distinguish the three lines of the Fe XXV triplet at 6.61, 6.67, and 6.72 keV, with equivalent widths of 6, 9, and 5 eV, respectively. The equivalent width of the Kα neutral iron line is 13 eV, an order of magnitude low…

Accurate Period Determination of an Eclipsing Binary X-Ray Source in M33

1993

We have analyzed the time variability of one of the X-ray sources in M33 observed by both the ROSAT and Einstein Observatory telescopes. The light curve of M33 X-7 exhibits a variability pattern of high and low states, suggesting an eclipsing binary X-ray source. The data suggest a binary period P=1.78572 days (very close to that of Her X-1) and an eclipse duration of ∼0.4 days. The low phase lasts about one-fourth of the period as in Cen X-3

VSOP monitoring of the Quasar 1928+738

1999

One limitation of the VSOP (VLBI Space Observatory Program) mission is that several famous superluminal sources such as 3C273 cannot be monitored with good uv-coverage throughout the lifetime of the VSOP Mission at regular intervals that are spaced closely enough to follow the evolution in the fine-scale source-structure. The reason for this is that the HALCA spacecraft cannot#observe sources outside certain restricted ranges of sun angle, defined to be the time variable angle between the source and the sun. However sources that lie within 10 degrees of the ecliptic poles can be observed throughout the year and observations are not restricted to narrow temporal windows. Furthermore, the bes…

X-Ray Eclipse Time Delays in 4U2129+47

2007

4U 2129+47 was discovered in the early 80's and classified as an accretion disk corona source due to its broad and partial X-ray eclipses. The 5.24 hr binary orbital period was inferred from the X-ray and optical light curve modulation, implying a late K or M spectral type companion star. The source entered a low state in 1983, during which the optical modulation disappeared and an F8 IV star was revealed, suggesting that 4U 2129+47 might be part of a triple system. The nature of 4U 2129+47 has since been investigated, but no definitive conclusion has been reached. Here, we present timing and spectral analyses of two XMM-Newton observations of this source, carried out in May and June, 2005.…

The stellar population of the Rosat North Ecliptic Pole survey. II. Spectral analysis

2008

X-ray surveys allow to identify young, main-sequence stars in the solar neighborhood. Young, stellar samples, selected according to their activity, can be used to determine the stellar birthrate in the last billion years. The ROSAT North Ecliptic Pole survey (NEP), with its moderately deep sensitivity (fluxes ~10^(-14) erg cm^(-2) sec^(-1)), is the best survey, to date, able to sample the intermediate-age (10^8 - 10^9 years) nearby population. The identification process of NEP X-ray sources resulted in 144 X-ray sources having a normal stellar counterpart, with an excess of yellow stars with respect to model predictions. We want to determine if these X-ray active stars are young or intermed…

The stellar population of the Rosat North Ecliptic Pole survey

2006

Context. X-ray surveys are a very efficient mean of detecting young stars and therefore allow us to study the young stellar population in the solar neighborhood and the local star formation history in the last billion of years. Aims. We want to study the young stellar population in the solar neighborhood, to constrain its spatial density and scale height as well as the recent local star formation history. Methods. We analyze the stellar content of the ROSAT North Ecliptic Pole survey, and compare the observations with the predictions derived from stellar galactic model. Since the ROSAT NEP survey is sensitive at intermediate fluxes is able to sample both the youngest stars and the intermedi…

The OpenUp Process

2014

The Open Unified Process (OpenUp) is an iterative design process that structures the project lifecycle into four phases: Inception, Elaboration, Construction, and Transition. It is part of the Eclipse Process Framework and embraces a pragmatic, agile philosophy that focuses on the collaborative nature of software development. It is a tools-agnostic, low-ceremony process that can be extended to address a broad variety of project types. The project lifecycle provides stakeholders and team members with visibility and decision points throughout the project and makes them able to manage their work through micro-increments.

Management of Complex Cerebral Aneurysms

2022

BACKGROUND: Complex intracranial aneurysms (CIAs) are challenging pathologies to treat. Characteristics making an aneurysm complex include dimension, history of previous treatment, location, absence of collateral circulation, intraluminal thrombosis, and calcification of the wall. The goal of the therapeutic process is to exclude the malformation from the cerebral circulation and both endovascular and surgical treatments are valid procedures.METHODS: Between 1990 and 2020, 170 CIAs were treated at our institution (33 ruptured, 137 unruptured). They were 3 prepetrous segment of the internal carotid artery (ICA), 14 purely intracavernous sinus, 27 intracavernous with subarachnoid extension, 6…

Accretion onto Neutron Stars: spectral and timing investigation of Low Mass X-ray Binaries

2021

La città di Alphabet. Architettura per prosumers.

2021

Attraverso alcuni aspetti salienti dell’ideazione, della produzione e dell’opposizione al progetto del Toronto Quayside di Sidewalk labs, l’articolo discute l’influenza delle infrastrutture digitali per l’informazione sul progetto della casa e del quartiere. L’ampliamento delle attività svolte da remoto nello spazio domestico, enfatizzato dal quotidiano della pandemia da Covid 19, costituisce per gli oligopolisti planetari degli urban data come Alphabet un utile volano pubblicitario e un acceleratore. La fusione dei nuovi vessilli della tecnoemancipazione e della sostenibilità in ipotesi sperimentali che mirano a costruirsi sia per intero che per parti realizza un nuovo orizzonte in cui lo …