Search Publications
Identification of the broad solar emission features near 117 nm
Kurucz, R. L.; Avrett, E. H.; Loeser, R.
Wilhelm et al. have recently called attention to the unidentified broad emission features near 117 nm in the solar spectrum. They discuss the observed properties of these features in detail but do not identify the source of this emission. We show that the broad autoionizing transitions of neutral sulfur are responsible for these emission features.…
Matched filters for source detection in the Poissonian noise regime
Stewart, I. M.
A procedure is described for estimating an optimum kernel for the detection by convolution of signals among Poissonian noise. The technique is applied to the detection of X-ray point sources in XMM-Newton data, and is shown to yield an improvement in detection sensitivity of up to 60% over the sliding-box method used in the creation of the 1XMM ca…
GMRT observations of the field of INTEGRAL X-ray sources. II
Durouchoux, P.; Ishwara-Chandra, C. H.; Manchanda, R. +2 more
We conducted low-frequency radio observations with the Giant Metrewave Radio Telescope (GMRT) of the 40 new hard X-ray sources discovered by the INTEGRAL satellite. This survey was conducted in order to study radio emissions from these sources, to provide precise position, and to identify new microquasar candidates. Our observations show that 24 o…
A compact flare eclipsed in the corona of SV Camelopardalis
Sanz-Forcada, J.; Micela, G.; Favata, F.
The eclipsing active binary SV Cam (G0V/K6V, Porb=0.593071 d) was observed with XMM-Newton during two campaigns in 2001 and 2003. No eclipses in the quiescent emission are clearly identified, but a flare was eclipsed during the 2001 campaign, allowing us to strongly constrain, from purely geometrical considerations, the position and siz…
Transition region counterpart of a moving magnetic feature
Doyle, J. G.; Banerjee, D.; O'Shea, E. +1 more
Context: .While moving magnetic features have been studied extensively at the photospheric level, the effect they have on the upper atmosphere remains largely unknown, and it is this which we seek to address in this work.
Aims: .In this work we aim to investigate the chromospheric and transition-region dynamics associated with a moving magneti…
Lithium abundances for early F stars: new observational constraints for the Li dilution
Recio-Blanco, A.; de Laverny, P.; de Medeiros, J. R. +2 more
Aims.To investigate any correlation between Li abundances and rotational velocities among F-G evolved stars, we study a large sample of early F stars from the Bright Star Catalogue (BSC), most of them classified in the literature as giant stars.
Methods.Physical parameters and Li abundances are estimated for each star, often for the first time,…
On the dynamical stability of the Rosetta orbiter. I.
Mysen, E.; Aksnes, K.
The Rosetta probe is to monitor, from a bound orbit, its primary target comet 67P/Churyumov-Gerasimenko for extended periods of time. As a preliminary assessment of the challenges involved, the strengths of the effects which perturb the spacecraft's cometocentric Keplerian trajectory are evaluated. It is found that in our adopted nominal scenario,…
Restoring color-magnitude diagrams with the Richardson-Lucy algorithm
Cignoni, M.; Shore, S. N.
Aims.We present an application of the Richardson-Lucy algorithm to the analysis of color-magnitude diagrams by converting the CMD into an image and using a restoring point spread function function (psf) derived from the known, often complex, sources of error.
Methods: .We show numerical experiments that demonstrate good recovery of the origina…
PG 0844+349 revisited - is there any outflow?
Wang, T.; Brinkmann, W.; Grupe, D. +1 more
Aims.The detection of high velocity absorption lines from highly ionized material has been reported recently from the X-ray spectrum of the narrow line Seyfert 1 galaxy PG 0844+349 and were interpreted as a relativistic outflow from the source. We studied this outflow because it would have important implications for our understanding of narrow lin…
Time-dependent 3D modulation of Jovian electrons. Comparison with Ulysses/KET observations
Fichtner, H.; Kissmann, R.; Lange, D.
We report on the modelling of the time-dependent transport of a few MeV electrons in the heliosphere. These low-energetic electrons, observed with the Kiel Electron Telescope (KET) on board the Ulysses spacecraft, are for the first time simulated over a complete solar activity cycle on the basis of a time-dependent three-dimensional modulation mod…