Search Publications
Properties of prominence fine-structure threads derived from SOHO/SUMER hydrogen Lyman lines
Heinzel, P.; Anzer, U.; Schmieder, B. +2 more
Context: The SOHO/SUMER observations provide us for the first time with the prominence spectra in the Lyman-α line outside the attenuator together with the higher members of the hydrogen Lyman series.
Aims: We derive the prominence fine-structure thread properties by comparing the SOHO/SUMER hydrogen Lyman series observations with the syntheti…
Exploring the connection between the stellar wind and the non-thermal emission in LS 5039
Motch, C.; Janot-Pacheco, E.; Negueruela, I. +5 more
Context: LS 5039 has been observed with several X-ray instruments so far showing quite steady emission in the long term and no signatures of accretion disk. The source also presents X-ray variability at orbital timescales in flux and photon index. The system harbors an O-type main sequence star with moderate mass-loss. At present, the link between…
Hard X-ray flares in IGR J08408-4503 unveil clumpy stellar winds
Masetti, N.; Walter, R.; Produit, N. +2 more
Context: A 1000-s flare from a new hard X-ray transient,
Discovery of X-ray burst triplets in EXO 0748-676
Boirin, L.; Lewin, W. H. G.; in't Zand, J. J. M. +5 more
Type-I X-ray bursts are thermonuclear flashes that take place on the surface of accreting neutron stars. The wait time between consecutive bursts is set by the time required to accumulate the fuel needed to trigger a new burst; this is at least one hour. Sometimes secondary bursts are observed, approximately 10 min after the main burst. These shor…
High-resolution ultraviolet spectroscopy of PG 1159-035 with HST and FUSE
Rauch, T.; Werner, K.; Kruk, J. W. +3 more
Context: PG 1159-035 is the prototype of the PG 1159 spectral class which consists of extremely hot hydrogen-deficient (pre-) white dwarfs. It is also the prototype of the GW Vir variables, which are non-radial g-mode pulsators. The study of PG 1159 stars reveals insight into stellar evolution and nucleosynthesis during AGB and post-AGB phases.
The HELLAS2XMM survey. XI. Unveiling the nature of X-ray bright optically normal galaxies
Fiore, F.; Vignali, C.; Comastri, A. +8 more
Aims:X-ray bright optically normal galaxies (XBONGs) constitute a small but significant fraction of hard X-ray selected sources in recent Chandra and XMM-Newton surveys. Even though several possibilities were proposed to explain why a relatively luminous hard X-ray source does not leave any significant signature of its presence in terms of optical…
A new paradigm for the X-ray emission of O stars from XMM-Newton observations of the O9.7 supergiant ζ Orionis
Pollock, A. M. T.
XMM-Newton observations of the O supergiant ζ Orionis (O9.7 Ib) extend knowledge of its high-resolution spectrum beyond the C VI line at 33.7 Å and suggest a new framework for the interpretation of the X-ray spectra of single hot stars. All the lines are broad and asymmetric with similar velocity profiles. X-rays probably originate in the wind's t…
Evidence for wave harmonics in cool loops
Srivastava, A. K.; Doyle, J. G.; Banerjee, D. +1 more
Aims:Using temporal series image data from the Coronal Diagnostic Spectrometer (CDS) on SOHO, we study oscillations found in intensity (radiance) measurements from the transition region O v 629 line with the aim of finding evidence of wave harmonics in cool loops.
Methods: Using standard Fourier techniques, together with a pre-whitening method…
INTEGRAL observation of the accreting pulsar GX 1+4
Santangelo, A.; Wilms, J.; Segreto, A. +4 more
Aims:We present the results of the INTEGRAL monitoring campaign on the accreting low mass X-ray binary pulsar GX 1+4 performed during the Galactic plane scan of the INTEGRAL Core Programme.
Methods: The source was observed in different luminosity states ranging from L20-40 keV= 1.7 × 10-10 erg cm-2 s^{-1}, to L…
XMM-Newton observations of the eastern jet of SS 433
Burwitz, V.; Pratt, G. W.; Kawai, N. +2 more
Context: The radio supernova remnant W50 hosts at its center the peculiar galactic X-ray binary SS 433. It shows a central spherical structure with two "ears" which are supposed to be formed by the interaction of the precessing jets of SS 433 with the supernova shell.
Aims: A study of the spectral and spatial structure of the X-ray emission ca…