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The evolutionary status of the bright high-latitude supergiant HD 190390
Cuypers, J.; Reyniers, M.
Despite its mean apparent magnitude of mV = 6.39, the evolutionary status of
Energetic Electrons in Loop Top and Footpoint Microwave Sources
Zhou, A. H.; Su, Y. N.; Huang, G. L.
We have studied two microwave events with one-loop top (LT) and two-footpoint (FP) sources observed at 17 and 34 GHz by the Nobeyama Radioheliograph (NoRH). The microwave brightness peak is located near the FPs of the flare loop for one event, but near the LT for the other event. The microwave spectra of the FP sources are considerably softer (by …
Structures of Sub-keV Ions Inside the Ring Current Region
Lundin, R.; Yamauchi, M.; Dandouras, I. +5 more
The Jacobi constant for a cometary orbiter
Mysen, E.; Aksnes, K.
The Jacobi constant of a probe under the gravitational attraction of a rotating irregular body is rederived for excited, but free rigid rotation of the central mass. A related Tisserand-like quantity is found to be sufficiently conserved for it to qualify as a pseudo-integral. The quantity's near constancy is shown to imply that certain regions in…
Optical and X-Ray Observations of the Symbiotic System Ag Draconis During Quiescence and Outburst
Friedjung, Michael; González-Riestra, Rosario; Greiner, Jochen +6 more
We review the main characteristics of the symbiotic system AG Draconis, with special emphasis on its optical and X-ray variations. We also discuss the X-ray to visual energy distribution during quiescence and outburst and describe our spectroscopic and X-ray observations during the 2003 outburst.
Hector Servadac et les comètes de Jules Verne.
Crovisier, J.
"Hector Servadac" ("Off on a Comet") is a novel by Jules Verne published in 1877. Anticipating the Rosetta mission, it fantasizes about the in situ exploration of a comet by a small group of castaways. This novel illustrates what was publicly known on comets at that time.
Tentative detection of warm intervening gas towards PKS 0548-322 with XMM-Newton
Sako, M.; Barcons, X.; Carrera, F. J. +2 more
We present the results of a long (~93 ks) XMM-Newton observation of the bright BL-Lac object PKS 0548-322 (z= 0.069). Our Reflection Grating Spectrometer (RGS) spectrum shows a single absorption feature at an observed wavelength λ= 23.33 +/- 0.01 Å, which we interpret as OVI Kα absorption at z= 0.058, i.e. ~3000 km s-1 from the backgrou…
Proper motion study of the ROSAT selected WTTS candidates around Taurus-Auriga
LI, J. Z.
Astrometric study of the T Tauri stars (TTS) candidates and non-TTS X-ray sources around Tau-Aur [Li, Hu 132 (1998) 173], based on the Hipparcos and the ACT Reference Catalogue, is presented in this paper. The ROSAT selected X-ray sources are found to have complicated nature. A few of them are associated with the Tau-Aur or the Orion Star Forming …
Drifting field-aligned density structures in the night-side polar cap
Gurnett, D. A.; Persoon, A. M.; Pickett, J. S. +5 more
Spatio-temporal properties of density irregularities in the night-side polar cap are inferred from multi-point observations of auroral hiss at a radial distance of 5 Earth radii. In this case study, we use high resolution data of the wave instruments onboard the four Cluster spacecraft to estimate the local plasma density, obtaining values close t…
Shading under Titan's sky
Grieger, B.
During the descent of the Huygens probe in January 2005, its Descent Imager/Spectral Radiometer (DISR) will take the first close up images of Titan's surface. The shading imposed by the illumination of a planetary surface contains information on its topography. For planetary bodies without an optically thick atmosphere, the light can be assumed to…