Search Publications
XMM-Newton observations of 1A 0535+262 in quiescence
Tsygankov, S.; Santangelo, A.; Doroshenko, V. +3 more
Accretion onto magnetized neutron stars is expected to be centrifugally inhibited at low accretion rates. Several sources, however, are known to pulsate in quiescence at luminosities below the theoretical limit predicted for the onset of the centrifugal barrier. The source
GRB 120711A: an intense INTEGRAL burst with long-lasting soft γ-ray emission and a powerful optical flash
Covino, S.; Fugazza, D.; Greiner, J. +20 more
A long and intense γ-ray burst (GRB) was detected by INTEGRAL on 11 July 2012 with a duration of ~115 s and fluence of 2.8 × 10-4 erg cm-2 in the 20 keV-8 MeV energy range. GRB 120711A was at z ~ 1.405 and produced soft γ-ray emission (>20 keV) for at least ~10 ks after the trigger. The GRB was observed by several ground-b…
Resolved Multifrequency Radio Observations of GG Tau
Wilner, D. J.; Testi, L.; Henning, Th. +20 more
We present subarcsecond resolution observations of continuum emission associated with the GG Tau quadruple star system at wavelengths of 1.3, 2.8, 7.3, and 50 mm. These data confirm that the GG Tau A binary is encircled by a circumbinary ring at a radius of 235 AU with a FWHM width of ~60 AU. We find no clear evidence for a radial gradient in the …
A physical model for the X-ray time lags of narrow-line Seyfert type 1 active galactic nuclei
Done, Chris; Gardner, Emma
We study the origin of the soft X-ray excess seen in the `simple' narrow-line Seyfert 1 galaxy PG1244+026 using all available spectral-timing information. This object shows the now ubiquitous switch between soft leading the hard band on long time-scales, to the opposite behaviour on short time-scales. This is interpreted as a combination of intrin…
The yellow hypergiant HR 5171 A: Resolving a massive interacting binary in the common envelope phase
Smith, N.; Meilland, A.; Millour, F. +20 more
Context. Only a few stars are caught in the very brief and often crucial stages when they quickly traverse the Hertzsprung-Russell diagram, and none has yet been spatially resolved in the mass transfer phase.
Aims: We initiated long-term optical interferometry monitoring of the diameters of massive and unstable yellow hypergiants (YHG) with t…
Dissecting the origin of the submillimetre emission in nearby galaxies with Herschel and LABOCA
Roussel, H.; Hunt, L. K.; Weiss, A. +17 more
We model the infrared to submillimetre spectral energy distribution of 11 nearby galaxies of the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel sample using Spitzer and Herschel data and compare model extrapolations at 870 µm (using different fitting techniques) with Large APEX BOlometer CAmera (LABOCA) 870 µm obs…
Coronal Holes in Solar Cycles 21 to 23
Tlatov, A.; Tavastsherna, K.; Vasil'eva, V.
We present identifications of coronal holes (CHs) from observations in the He I 10 830 Å line made at Kitt Peak Observatory (from 1975 to 2003) and in the EUV 195 Å wavelength with SOHO/EIT (from 1996 to 2012). To determine whether a feature is a CH we have developed semi-automatic techniques for delineating CH borders on synoptic charts and for s…
Evolution of the Magnetic Helicity Flux during the Formation and Eruption of Flux Ropes
Guglielmino, S. L.; Romano, P.; Zuccarello, F. P. +1 more
We describe the evolution and the magnetic helicity flux for two active regions (ARs) since their appearance on the solar disk: NOAA 11318 and NOAA 11675. Both ARs hosted the formation and destabilization of magnetic flux ropes. In the former AR, the formation of the flux rope culminated in a flare of C2.3 GOES class and a coronal mass ejection (C…
An Early Look of Comet C/2013 A1 (Siding Spring): Breathtaker or Nightmare?
Ye, Quan-Zhi; Hui, Man-To
The dynamically new comet, C/2013 A1 (Siding Spring), is to make a close approach to Mars on 2014 October 19 at 18:30 UT at a distance of 40 ± 1 Martian radii. Such an extremely rare event offers a precious opportunity for the spacecrafts on Mars to closely study a dynamically new comet itself as well as the planet-comet interaction. Meanwhile, th…
Multiwavelength Observations of Swift J1753.5-0127
Maccarone, Thomas J.; France, Kevin; Lewis, Fraser +4 more
We present contemporaneous X-ray, ultraviolet (UV), optical, and near-infrared observations of the black hole binary system Swift J1753.5-0127 acquired in 2012 October. The UV observations, obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope, are the first UV spectra of this system. The dereddened UV spectrum is characteriz…