Extreme Variability in the Be-Type, Periodic Recurrent X-Ray Transient A0538 - 66: A Highly Eccentric Interacting Binary

We present optical spectroscopy and photometry and IUE spectroscopy of the counterpart of the extremely powerful LMC recurrent X-ray transient A0538 – 66. During one 16.6 day outburst cycle at the end of 1980 December the optical spectra show steadily increasing Balmer and He I emission (indicative of an expanding envelope) superposed on a B2 III–IV spectrum. There is a substantial optical brightness increase of 2 mag at the peak, accompanied by the sudden turn-on of He IIλ 4686. These and other optical spectra show significant radial velocity changes but we can find no clear correlation with the 16.6 day cycle. Further optical and IUE spectra were obtained at the peak of subsequent outbursts, and these show very strong and broad (∼ 5000 km s−1) emission lines. We interpret the system as a ∼ 1 M⊙ compact object in a highly eccentric (e ∼ 0.7) orbit about the ∼ 12 M⊙ B star with a binary period equal to the flare period. Continuum measurements indicate that the emitting region at outburst is several times the size of the B star thus implying that at periastron passage the envelope of the primary is tidally expanded by the neutron star. Although this is now the best example of a growing group of recurrent X-ray transients, A0538 – 66 is unique in its optical behaviour and peak Lx when compared with other galactic X-ray transients and shell/Be stars

Determining the accuracy of zero-flux and ingestible thermometers in the peri-operative setting

Accurately monitoring peri-operative core temperature is a cornerstone of good practice. Relatively invasive devices such as oesophageal temperature probes and pulmonary artery catheters facilitate this, but are inappropriate for many patients. There remains a need for accurate monitors of core temperature that can be used in awake patients. This study compared the accuracy of two core temperature thermometers that can be used for this purpose: the 3M Bair Hugger™ Temperature Monitoring System Zero Flux Thermometer and the CorTempR™ Wireless Ingestible Temperature Sensor. Readings were compared with the oesophageal probe, the current intraoperative standard. Thirty patients undergoing elective surgical procedures under general anaesthesia were recruited. The ingestible sensor was ingested prior to induction of anaethesia, and post induction, the zero-flux electrode attached above the right eyebrow and oesophageal probe inserted. During surgery, the temperature on each device was recorded every minute. Measurements were compared using Bland–Altman analysis. The ingestible sensor experienced interference from use of diathermy and fluoroscopy in the operating theatre, rendering 39% of its readings unusable. These were removed from analysis. With remaining readings the bias compared with oesophageal probe was + 0.42 °C, with 95% limits of agreement − 2.4 °C to 3.2 °C. 75.4% of readings were within ± 0.5 °C of the OTP reading. The bias for the zero flux electrode compared to oesophageal probe was + 0.02 °C with 95% limits of agreement − 0.5 °C to 0.5 °C. 97.7% of readings were within ± 0.5 °C of the oesophageal probe. The study findings suggest the zero-flux thermometer is sufficiently accurate for clinical use, whereas the ingestible sensor is not

On the nature of XTE J0421+560/CI Cam

We present the results of the analysis of RXTE, BATSE and optical/infrared data of the 1998 outburst of the X-ray transient system XTE J0421+560 (CI Cam). The X-ray outburst shows a very fast decay (initial e-folding time ~0.5 days, slowing down to ~2.3 days). The X-ray spectrum in the 2-25 keV band is complex, softening considerably during decay and with strongly variable intrinsic absorption. A strong iron emission line is observed. No fast time variability is detected (<0.5 % rms in the 1-4096 Hz band at the outburst peak). The analysis of the optical/IR data suggests that the secondary is a B[e] star surrounded by cool dust and places the system at a distance of >~ 2 kpc. At this distance the peak 2-25 keV luminosity is ~4 x 10^37 erg/s. We compare the properties of this peculiar system with those of the Be/NS LMC transient A 0538-66 and suggest that CI Cam is of similar nature. The presence of strong radio emission during outburst indicates that the compact object is likely to be a black hole or a weakly magnetized neutron star.Comment: Accepted for publication on The Astrophysical Journal, July 199

The Orbit of the High-Mass X-Ray Binary Pulsar 1E1145.1-6141

Observations of the 297 s X-ray pulsar 1E1145.1-6141 with the Rossi X-Ray Timing Explorer have revealed its 14.4 d eccentric orbit around its B supergiant companion. The best-fit orbital elements are: P_orb = 14.365(2) d, a_x sin i=99.4(18) light-s, e=0.20(3). No eclipses are detected, indicating that the binary inclination is less than 55 deg.Comment: 10 pages, 4 figures, accepted for publication in Ap

A Feasibility Experiment of a W-powder Target

The development of high‐powertargetsremains a key R&D actvity for future facilities presently under study like the Neutrino Factory, Muon Collider or upgraded high‐power super beams for long‐baseline neutrino experiments. The choice of materials to sustain the beam power ranging up to MW levels is not trivial.Granular solid targets have been proposed and are being studied as a candidate for such high-power target systems. In the recently commissioned HiRadMat facility at CERN, a feasibility experiment of a tungsten powder target was performed. The experiment was designed to explore for first time the impact of a high‐power proton beam on a static W powder target in a thimble configuration. The diagnostics of the experiment were based on remote high‐speed photography as well as on laser‐doppler vibration measurements of the target containers. Results from the experimental findings are presented in this poster

INTEGRAL observation of the accreting pulsar 1E1145.1-6141

We analyze 1050 ks of INTEGRAL data of the high mass X-ray binary pulsar 1E 1145.1-6141 to study its properties over a long time baseline, from June 2003 to June 2004, with wide spectral coverage. We study three high luminosity episodes, two of them at the system apoastron, three brightening with lower intensity, two at the periastron, and one extended period of intermediate luminosity spanning one orbital cycle. We perform timing analysis to determine the pulse period and pulse profiles at different energy ranges. We also analyze the broad band phase average spectrum of different luminosity states and perform phase resolved spectroscopy for the first flare. From the timing analysis, we find a pulse period of ~297 s around MJD 53000 with a significant scatter around the mean value. From the spectral analysis we find that the source emission can be described by an absorbed bremsstrahlung model in which the electron temperature varies between ~25 and ~37 keV, without any correlation to luminosity, and the intrinsic absorbing column is constantly of the order of 10^23 cm^-2. Phase resolved spectral analysis evidences a different temperature of the plasma in the ascending and descending edges of the pulse during the first flare. This justifies the pulse maximum shift by ~0.4 phase units between 20 and 100 keV observed in the pulse profiles. The comparison with the previous period measurements reveals that the source is currently spinning-down, in contrast to the long term secular trend observed so far indicating that at least a temporary accretion disk is formed. The study of the spectral property variations with respect to time and spin phase suggests the presence of two emitting components at different temperatures whose relative intensity varies with time.Comment: Accepted for publication on Astronomy and Astrophysic