Search results for "CLIPS"

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

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 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.

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 …

A possible solution of the puzzling variation of the orbital period of MXB 1659-298

2017

MXB 1659-298 is a transient neutron star Low-Mass X-ray binary system that shows eclipses with a periodicity of 7.1 hr. The source went to outburst in August 2015 after 14 years of quiescence. We investigate the orbital properties of this source with a baseline of 40 years obtained combining the eight eclipse arrival times present in literature with 51 eclipse arrival times collected during the last two outbursts. A quadratic ephemeris does not fit the delays associated with the eclipse arrival times and the addition of a sinusoidal term with a period of $2.31 \pm 0.02$ yr is required. We infer a binary orbital period of $P=7.1161099(3)$ hr and an orbital period derivative of $\dot{P}=-8.5(…

Multi-epoch VLTI-PIONIER imaging of the supergiant V766 Cen

2017

Context. The star V766 Cen (=HR 5171A) was originally classified as a yellow hypergiant but lately found to more likely be a 27-36 M red supergiant (RSG). Recent observations indicated a close eclipsing companion in the contact or common-envelope phase. Aims. Here, we aim at imaging observations of V766 Cen to confirm the presence of the close companion. Methods. We used near-infrared H-band aperture synthesis imaging at three epochs in 2014, 2016, and 2017, employing the PIONIER instrument at the Very Large Telescope Interferometer (VLTI). Results. The visibility data indicate a mean Rosseland angular diameter of 4.1 ± 0.8 mas, corresponding to a radius of 1575 ± 400 R. The data show an ex…

Els viatges de la física: perseguint ombres, mesurant meridians

2013

A partir del segle XVII l’estudi acurat i resolució de diversos problemes de la física, principalment relacionats amb l’astronomia i la forma de la Terra, però no sols, ha passat per realitzar mesures a diferents llocs i, per tant, per l’organització de viatges científics amb aquests objectius específics. Presentarem alguns d’aquests problemes i les solucions adoptades a l’època.

Critical proofreading of the book "Les derniers jours du siège d'Alésia"

2023

Was there a lunar eclipse that could have influenced the outcome of the Battle of Alesia? This is the argument developed in the book by Alain Deyber and David Romeuf, «Les Derniers Jours du Siège d'Alésia». Having verified the existence of an eclipse on the date given by the authors and based on the latest publications as well as on the scientific consensus, we conduct a critical study on the chronology of the siege and on the ethnological arguments, even ethno-astronomical of the authors.