Search Publications
CCD astrometry and components instrumental magnitude difference of 432 Hipparcos wide visual double stars
Gavras, P.; Sinachopoulos, D.; Dionatos, O. +2 more
Context: We measured the angular separations, position angles, Δ V, Δ y and Δ I of wide visual double stars during the period 2003-2005. At least one component of the double stars in our sample has an entry in the Hipparcos catalogue.
Aims: Our measurements are a contribution to the study of the nature of these double stars.
Methods: The n…
How much oxygen is too much? Constraining Saturn's ring atmosphere
Goldreich, Peter; Farmer, Alison J.
The discovery of a molecular oxygen atmosphere around Saturn's rings has important implications for the electrodynamics of the ring system. Its existence was inferred from the Cassini in situ detection of molecular oxygen ions above the rings during Saturn Orbit Insertion in 2004. Molecular oxygen is difficult to observe remotely, and theoretical …
INTEGRAL high energy detection of the transient IGR J11321-5311
Hill, A. B.; Bird, A. J.; Ubertini, P. +5 more
Context: The transient hard X-ray source IGR J11321-5311 was discovered by INTEGRAL on June 2005, during observations of the Crux spiral arm. To date, this is the only detection of the source to be reported by any X/γ-ray mission.
Aims: To characterize the behaviour and hence the nature of the source through temporal and spectral IBIS analysis…
Radiative transfer in layered media: Application to the radar sounding of Martian polar ices. II
Ilyushin, Ya. A.
The paper addresses the problem of the retrieval of the physical parameters of the Martian polar ices from the ground-penetrating radar (GPR) measurements. The results of the previous paper [Ilyushin, Y.A., Seu, R., Phillips, R.J., 2005. Subsurface radar sounding of the Martian polar cap: radiative transfer approach. Planet. Space Sci. 53(14-15), …
A spectroscopic search for non-radial pulsations in the δ Scuti star γ Bootis
Christensen-Dalsgaard, J.; Catanzaro, G.; Ventura, R. +2 more
High-resolution spectroscopic observations of the rapidly rotating δScuti star γBootis have been carried out in 2005, over six consecutive nights, in order to search for line-profile variability. Time-series, consisting of flux measurements at each wavelength bin across the TiII 4571.917 Å line profile as a function of time, have been Fourier anal…
Cluster observations of broadband ULF waves near the dayside polar cap boundary: Two detailed multi-instrument event studies
Farrugia, C. J.; Lucek, E. A.; Mouikis, C. G. +6 more
We study two examples of broadband ultra-low frequency (ULF) waves observed near the dayside polar cap boundary using data from multiple instruments on Cluster. These waves lie in a frequency range of ∼1-100 mHz with variable amplitudes. We have focused on their characteristics around the lowest frequency end. In the first event, the magnetic vari…
Long term spectral variability in the soft gamma-ray repeater SGR 1900+14
Mereghetti, Sandro; Esposito, Paolo; Turolla, Roberto +8 more
We present a systematic analysis of all the BeppoSAX data of SGR1900+14. The observations spanning five years show that the source was brighter than usual on two occasions: ∼20 days after the August 1998 giant flare and during the 105 s long X-ray afterglow following the April 2001 intermediate flare. In the latter case, we explore the …
Mass modelling with minimum kinematic information
Chakrabarty, Dalia
Mass modelling of early-type systems is a thorny issue; even for the few close by galaxies for which kinematic data are available, the implementation of this data can get embroiled in problems that are hard to overcome, unless more complete data sets are available. The mass-anisotropy degeneracy is a typical example of this. In this paper, we pres…
Banana-polarized solitons in anisotropic plasmas related to Ulysses observations
Dubinin, E.; Sauer, K.; Baumgärtel, K. +1 more
Localized magnetic compressions associated with a rotation in the magnetic field direction have recently been reported after surveying Ulysses high-resolution data. Although the observed structures have similarities to usual Hall-MHD solitons, the banana-type polarization of the described rare events is a decisive signature which counts against su…
Keck HIRES Spectroscopy of Candidate Post-T Tauri Stars
Deliyannis, Constantine P.; Soderblom, David R.; King, Jeremy R. +2 more
We use high signal-to-noise ratio (~150-450), high-resolution (R ~ 45,000) Keck HIRES spectroscopy of 13 candidate post-T Tauri stars (PTTs) to derive basic physical parameters, lithium abundances, and radial velocities. We place our stars in the Mv-Teff plane for use in determining approximate ages from pre-main-sequence iso…