Search Publications
INTEGRAL observations of PSR J1811-1925 and its associated pulsar wind nebula
de Rosa, A.; Hill, A. B.; Bird, A. J. +6 more
We present spectral measurements made in the soft (20-100keV) γ-ray band of the region containing the composite supernova remnant G11.2-0.3 and its associated pulsar PSR J1811-1925. Analysis of INTEGRAL/IBIS data allows characterization of the system above 10keV. The IBIS spectrum is best fitted by a power law having photon index Γ = 1.8+0.4<…
Multi-epoch spectroscopy of the globular cluster black hole in NGC 4472
Maccarone, T. J.; Kundu, A.; Zepf, S. E. +1 more
We present a study of the X-ray spectral properties of the highly variable X-ray emitting black hole in a globular cluster in the elliptical galaxy NGC 4472. The X-ray Multiple Mirror-Newton (XMM-Newton) spectrum of the source in its bright epoch is well described by a multiple blackbody model with a characteristic temperature kTin ~ 0.…
Bulk Compton motion in the luminous quasar 4C04.42?
de Rosa, A.; Ubertini, P.; Malizia, A. +2 more
We present the broadband analysis of the powerful quasar 4C04.42 (z = 0.965) observed by XMM-Newton and INTEGRAL. The 0.2-200keV spectrum is well reproduced with a hard power-law component (Γ ~ 1.2), augmented by a soft component below 2keV (observer frame), which is described by a thermal blackbody with temperature kT ⋍ 0.15keV. Alternatively, a …
Apsidal motion in southern eccentric eclipsing binaries: GL Car, QX Car, NO Pup and V366 Pup
Wolf, M.; Zejda, M.; de Villiers, S. N.
The study of apsidal motion in eccentric eclipsing binaries (EEB) provides an important observational test of theoretical models of stellar structure and evolution. The Southern hemisphere contains many interesting and also neglected binary systems. New accurate photoelectric times of minimum light have been obtained for the detached early-type So…
A search for rapid pulsations in the magnetic cool chemically peculiar star HD3980
Hubrig, S.; Kurtz, D. W.; Mathys, G. +2 more
The Ap star HD3980 appears to be a promising roAp candidate based on its fundamental parameters, leading us to search for rapid pulsations with the VLT UV-Visual Echelle Spectrograph (UVES). A precise Hipparcos parallax and estimated temperature of 8100K place HD3980 in the middle of the theoretical instability strip for rapidly oscillating Ap sta…
Simple stellar population models as probed by the Large Magellanic Cloud star cluster ESO 121-SC03
Mackey, A. D.; de Grijs, R.; Xin, Y. +2 more
The presence of blue straggler stars (BSs) in star clusters has proven a challenge to conventional simple stellar population (SSP) models. Conventional SSP models are based on the evolution theory of single stars. Meanwhile, the typical locations of BSs in the colour-magnitude diagram of a cluster are brighter and bluer than the main-sequence turn…
Discovery of X-ray pulsations from the HMXB source AXJ1749.1-2733
Tsygankov, S. S.; Lutovinov, A. A.; Karasev, D. I.
We are reporting the discovery of X-ray pulsations from the source AXJ1749.1-2733 with the period of ~132 s based on the XMM-Newton data obtained in 2007 March. The observed pulse profile has a double-peaked structure with the pulse fraction of about 25-30 per cent in the 3-10 keV energy band. We have also found that a periodicity with practically…
Phase models of the Milky Way stellar disc
Orlov, V. V.; Rodionov, S. A.
We present a new iterative method for constructing equilibrium phase models of stellar systems. Importantly, this method can provide phase models with arbitrary mass distributions. The method is based on the following principle. Our task is to generate an equilibrium N-body system with a given mass distribution. For this purpose, we let the system…
Puzzling X-rays from the new colliding wind binary Wolf-Rayet 65 (WC9d)
Hamann, W. -R.; Oskinova, L. M.
We report the discovery of variability in the X-ray emission from the Wolf-Rayet type star WR65. Using archival Chandra data spanning over 5yr, we detect changes of the X-ray flux by a factor of 3 accompanied by changes in the X-ray spectra. We believe that this X-ray emission originates from wind-wind collision in a massive binary system. The obs…
ATCA observations of the very young Planetary Nebula SAO 244567
Umana, G.; Trigilio, C.; Leto, P. +2 more
The radio emission from the youngest known Planetary Nebula, SAO244567, has been mapped at 1384, 2368, 4800, 8640, 16832 and 18752 MHz by using the Australian Telescope Compact Array (ATCA). These observations constitute the first detailed radio study of this very interesting object, as they allow us to obtain the overall radio morphology of the s…