Search Publications
51 Pegasi - a planet-bearing Maunder minimum candidate
Schmitt, J. H. M. M.; Robrade, J.; Poppenhäger, K. +1 more
We observed 51 Peg, the first detected planet-bearing star, in a 55 ks XMM-Newton pointing and in 5 ks pointings each with Chandra HRC-I and ACIS-S. The star has a very low count rate in the XMM observation, but is clearly visible in the Chandra images due to the detectors' different sensitivity at low X-ray energies. This allows a temperature est…
Asteroseismology and interferometry of the red giant star ɛ Ophiuchi
Goupil, M. -J.; Baudin, F.; Kervella, P. +16 more
The GIII red giant star ɛ Oph has been found to exhibit several modes of oscillation by the MOST mission. We interpret the observed frequencies of oscillation in terms of theoretical radial p-mode frequencies of stellar models. Evolutionary models of this star, in both shell H-burning and core He-burning phases of evolution, are constructed using …
INTEGRAL observation of hard X-ray variability of the TeV binary LS 5039/RX J1826.2-1450
Klochkov, D.; Santangelo, A.; Segreto, A. +4 more
Context: LS 5039 / RX J1826.2-1450 is one of the few High Mass X-ray binary systems from which radio and high energy TeV emission has been observed. Moreover, variability of the TeV emission with orbital period was detected.
Aims: We investigate the hard X-ray (25{-}200 keV) spectral and timing properties of the source with the monitoring IBIS…
Non-Maxwellian electron distributions in clusters of galaxies
Kaastra, J. S.; Werner, N.; Bykov, A. M.
Context: Thermal X-ray spectra of clusters of galaxies and other sources are commonly calculated assuming Maxwellian electron distributions. There are situations where this approximation is not valid, for instance near interfaces of hot and cold gas and near shocks.
Aims: The presence of non-thermal electrons affects the X-ray spectrum. To stu…
Long-term chromospheric activity of non-eclipsing RS CVn-type stars
Buccino, A. P.; Mauas, P. J. D.
Context: The IUE database provides several UV high and low-resolution spectra of RS CVn-type stars from 1978 to 1996. In particular, many of these stars were monitored continuously during several seasons by IUE.
Aims: Our main purpose is to study the short and long-term chromospheric activity of the RS CVn systems most observed by IUE: HD 22 4…
Removing systematics from the CoRoT light curves. I. Magnitude-dependent zero point
Mazeh, T.; Guterman, P.; Aigrain, S. +31 more
This paper presents an analysis that searched for systematic effects within the CoRoT exoplanet field light curves. The analysis identified a systematic effect that modified the zero point of most CoRoT exposures as a function of stellar magnitude. We could find this effect only after preparing a set of learning light curves that were relatively f…
Pre-nova X-ray observations of V2491 Cygni (Nova Cyg 2008b)
Mukai, K.; Hernanz, M.; Sala, G. +12 more
Classical novae are phenomena caused by explosive hydrogen burning onto an accreting white dwarf. Only one classical nova had been identified in X-rays before the actual optical outburst occurred (V2487 Oph). The recently discovered nova, V2491 Cyg, is one of the fastest (He/N) novae observed to date. Using archival ROSAT, XMM-Newton, and Swift da…
Spectral and temporal variations of the isolated neutron star RX J0720.4-3125: new XMM-Newton observations
Haberl, F.; de Vries, C. P.; Vink, J. +5 more
Context: In the past, the isolated, radio-quiet neutron star RX J0720.4-3125 showed variations in its spectral parameters (apparent radius, temperature of the emitting area and equivalent width of the absorption feature) seen in the X-ray spectra, not only during the spin period of 8.39 s, but also over time scales of years. New X-ray observations…
Results from DROXO. II. [Ne II] and X-ray emission from ρ Ophiuchi young stellar objects
Testi, L.; Micela, G.; Sciortino, S. +3 more
Context: The infrared [Ne II] and [Ne III] fine structure lines at 12.81 µm and 15.55 µm have recently been theoretically predicted to trace the circumstellar disk gas subject to X-ray heating and ionization.
Aims: We observationally investigate the origin of the neon fine structure line emission by comparing observations with mode…
Circumstellar water vapour in M-type AGB stars: constraints from H{2}O(1{10}-1{01}) lines obtained with Odin
Olofsson, H.; Justtanont, K.; Larsson, B. +8 more
Context: A detailed radiative transfer code has been previously used to model circumstellar ortho-{H_2O} line emission towards six M-type asymptotic giant branch stars using Infrared Space Observatory Long Wavelength Spectrometer data. Collisional and radiative excitation, including the {ν_2=1} state, was considered.
Aims: Spectrally resolved …