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Irradiation phenomena in young solar-type stars and the early solar system: X-ray observations and γ-ray constraints
Montmerle, Thierry
The high levels of X-ray flaring activity observed in young stars and protostars suggest correspondingly high levels of low-energy particle irradiation of their circumstellar disks, and hence of early solar system material like meteorites. We first briefly review the latest X-ray observational results obtained by Chandra and XMM-Newton on two 'typ…
Identification of RR Lyrae stars in the Tycho-2 catalogue
Mennessier, M. O.; Colomé, J.
The Tycho-2 catalogue provides astrometric and photometric data for the 2.5 million brightest stars in the sky. Therefore it can provide much larger samples than the Hipparcos samples used to date in statistical studies. The object of this paper is the cross-identification of Tycho-2 sources and known variable stars of RR Lyrae type. The Tycho-2 d…
Coronal mass ejections and emerging flux
Chen, P. F.; Shibata, K.; Fang, C. +1 more
This paper reviews our recent progress in the numerical study of coronal mass ejections (CMEs) based on flux rope model, which shows that when the reconnection-favored emerging flux appears either within or on the outer edge of the filament channel, the flux rope would lose its equilibrium, and be ejected, while a current sheet is formed below the…
COMMENT: Comment on 'Particle charge evolution during acceleration processes in solar flares' by M D Rodríguez-Frías, L del Peral and J Pérez-Peraza
Torsti, J.; Kocharov, L.; Kovaltsov, G. A.
Attention is drawn to the fact that results of the model obtained by Rodríguez-Frías et al are in conflict with both the straightforward physical consideration and the results of other models of charge-changing acceleration in solar flares. The numerical code given by Rodríguez-Frías et al generates an erroneous result that charge states of ions a…
Composition measurements above the Southern Solar Polar Region around the solar activity maximum by the Ulysses COSPIN/LET instrument
Sanderson, T. R.; Marsden, R. G.; Tranquille, C. +1 more
In November 2000, during the second southern polar passage (SPP), the Ulysses spacecraft reached its highest heliographic latitude (80.2°) at a solar radial distance of ~2.27 AU. The first SPP in 1994 took place as the level of solar activity was approaching the minimum between the cycles 22 and 23. The recent high-latitude observations during the…
Comment on ``Model of ionic charge states of impulsive solar energetic particles in solar flares'' by M. Dolores Rodríguez-Frías, Luis del Peral, and Jorge Pérez-Peraza
Kocharov, Leon; Torsti, Jarmo; Kovaltsov, Gennadi A. +2 more
Attention is drawn to the fact that the numerical code ESCAPE by [2001] is in conflict with other models of charge-changing processes in solar corona, including the most reliable model by [1992]. We find in the >0.1 MeV nucleon-1 energy range a tendency of the ESCAPE code to overestimate the ionic charge of iron. This implies an unde…
Fuzzy classification of coronal mass ejection properties
Tang, Y. H.; Han, Z. Z.
Fuzzy set theory is applied to a quantitative study of coronal mass ejection properties for importance category. The membership function can be determined according to statistical results and the correlation between CME morphology properties and characteristic factors. CME importance category has been obtained by data reduction. A useful software …
Star Formation in the radio galaxy NGC 4410A
Donahue, Megan; Stocke, John T.; Smith, Beverly J.
The NGC 4410 group of galaxies provides us with a rare opportunity to study a nearby (97 h-175 Mpc) example of a radio galaxy (NGC 4410A) embedded in an extended X-ray source, with evidence for star formation that can be readily spatially distinguished from regions dominated by the active galactic nucleus and shocks. We prese…
The radial velocities and physical parameters of HD 553
Iliev, L.; Iliev, I. Kh.; Duemmler, R.
Erratum: Radiation-driven winds of hot luminous stars. XIII. A Description of NLTE line blocking and blanketing towards realistic models for expanding atmospheres
Pauldrach, A. W. A.; Hoffmann, T. L.; Lennon, M.
We present significant improvements of our approach in constructing detailed atmospheric models and synthetic spectra for hot luminous stars: 1. A sophisticated and consistent description of line blocking and blanketing. Our solution concept renders the line blocking influence on the ionizing fluxes (mainly the EUV and UV are affected) in identica…