Search Publications
VLT optical observations of the isolated neutron star RX J0420.0-5022
Haberl, F.; Motch, C.; Mignani, R. P. +3 more
Context: X-ray observations performed with the Röntgen Satellite (ROSAT) led to the discovery of seven radio-silent isolated neutron stars (INSs) which are detected only through the relatively dim and purely thermal X-ray emission from the cooling star surface. A few of these INSs (X-ray Dim INSs, or XDINSs) have been also detected at optical wave…
Electron density in the quiet solar coronal transition region from SoHO/SUMER measurements of S VI line radiance and opacity
Vial, J. -C.; Buchlin, E.
Context: The steep temperature and density gradients that are measured in the coronal transition region challenge the model interpretation of observations.
Aims: We derive the average electron density < ne > in the region emitting the S vi lines. We use two different techniques, which allow us to derive linearly-weighted (opac…
Transit detections of extrasolar planets around main-sequence stars. I. Sky maps for hot Jupiters
Mislis, D.; Heller, R.; Antoniadis, J.
Context: The findings of more than 350 extrasolar planets, most of them nontransiting Hot Jupiters, have revealed correlations between the metallicity of the main-sequence (MS) host stars and planetary incidence. This connection can be used to calculate the planet formation probability around other stars, not yet known to have planetary companions…
Markov properties of solar granulation
Asensio Ramos, A.
Aims: We estimate the minimum length on which solar granulation can be considered to be a Markovian process.
Methods: We measure the variation in the bright difference between two pixels in images of the solar granulation for different distances between the pixels. This scale-dependent data is empirically analyzed to find the minimum scale on …
A deep XMM-Newton serendipitous survey of a middle-latitude area. II. New deeper X-ray and optical observations
Caraveo, P. A.; de Luca, A.; Schirmer, M. +4 more
Context: The radio-quiet neutron star 1E1207.4-5209 has been the target of several XMM-Newton observations, with a total exposure of ~350 ks. The source is located at intermediate galactic latitude (b ∼ 10°), i.e. in a sky region with an extremely interesting mix of both galactic and extra-galactic X-ray sources.
Aims: The aim of our work is t…
GRS 1915+105: high-energy insights with SPI/INTEGRAL. Spectral analysis of the Comptonized emission
Jourdain, E.; Droulans, R.
Context: We report on results of nearly two years of INTEGRAL/SPI monitoring of the Galactic microquasar GRS 1915+105.
Aims: From September 2004 to May 2006, the source was observed twenty times with long (~100 ks) exposures. We present an analysis of the SPI data and focus on the description of the high-energy (>20 keV) output of the sourc…
Properties of magnetic elements in the quiet Sun using the marker-controlled watershed method
Zhang, J.; Yang, S. H.; Xie, Z. X. +2 more
Context: The quiet Sun is an important part of understanding the global magnetic properties of the Sun. A recently launched observation system, named HINODE, provides a lot of high-resolution images for studying the quiet Sun. Obviously, it is time-consuming to analyze these images by hand. It is desirable to develop a technique for recognizing ma…
Observation of a solar energetic particle event behind previous coronal mass ejection
Laitinen, T.; Kocharov, L.; Al-Sawad, A. +1 more
On 2001 October 19-21 the Energetic and Relativistic Nuclei and Electron (ERNE) instrument on the Solar and Heliospheric Observatory (SOHO) observed two gradual solar energetic particle (SEP) events separated by 15 h, in association with two X1.6/2B solar flares and halo coronal mass ejections (CMEs). The observational data suggest that the second…
Effective area calibration of the reflection grating spectrometers of XMM-Newton. II. X-ray spectroscopy of DA white dwarfs
Kaastra, J. S.; Lanz, T.; Hubeny, I. +1 more
Context: White dwarf spectra have been widely used as a calibration source for X-ray and EUV instruments. The in-flight effective area calibration of the reflection grating spectrometers (RGS) of XMM-Newton depend upon the availability of reliable calibration sources.
Aims: We investigate how well these white dwarf spectra can be used as stand…
Revisiting the optical interferometry observations of HR 4049
Quirrenbach, A.; Lopez, B.; Chesneau, O. +4 more
Aims: We present high spatial resolution observations in the mid-infrared of the dusty core of the binary system HR 4049.
Methods: We used the mid-infrared interferometer MIDI/VLTI with 40 m projected baselines. These observations provided two spectrally dispersed visibility curves at a spatial resolution of ~10 mas. Acquisition images and spe…