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Evolution of Conjugate Footpoints inside Flare Ribbons during a Great Two-Ribbon Flare on 2001 April 10
Shimojo, Masumi; Yokoyama, Takaaki; Kurokawa, Hiroki +2 more
We report a detailed examination of the fine structure inside flare ribbons and the temporal evolution of such structure during an X2.3 solar flare, which occurred on 2001 April 10. We examined fine structures, such as systems of conjugate footpoints, inside flare ribbons by using the Hα images obtained with the Sartorius telescope at Kwasan Obser…
XMM-Newton high-resolution X-ray spectroscopy of the Wolf-Rayet object WR 25 in the Carina OB1 association
Schmutz, W.; Raassen, A. J. J.; Mewe, R. +5 more
We report the analysis of the first high-resolution X-ray spectra of the Wolf-Rayet (WR) object WR 25 (HD 93162, WN6ha+O4f) obtained with the Reflection Grating Spectrometers (RGS) and the European Photon Imaging Cameras (EPIC-MOS and PN) CCD spectrometers on board the XMM-Newton satellite. The spectrum exhibits bright emission lines of the H- and…
ISO-SWS calibration and the accurate modelling of cool-star atmospheres. IV. G9 to M2 stars
Eriksson, K.; Gustafsson, B.; Decin, L. +5 more
A detailed spectroscopic study of 11 giants with spectral type from G9 to M2 is presented. The 2.38-4.08 mu m wavelength-range of band 1 of ISO-SWS (Short-Wavelength Spectrometers on board of the Infrared Space Observatory) in which many different molecules - with their own dependence on each of the stellar parameters - are absorbing, enables us t…
Observations of the Sun's magnetic field during the recent solar maximum
Hoeksema, J. T.; Appourchaux, T.; Sanderson, T. R. +1 more
We present new observations and analyses of the Sun's magnetic field and coronal holes. Using magnetic field observations from the Wilcox Solar Observatory, we present a simple means whereby the tilt angle of the current sheet can be calculated. We use a data set covering the last 26 years, which shows for the first time how the dipole component r…
Selection of the landing site in Isidis Planitia of Mars probe Beagle 2
Head, J. W.; Rothery, D. A.; Duxbury, T. +14 more
This paper describes selection and characterization of the landing site for the Mars 2004 Beagle 2 mission. The site is within Isidis Planitia between 10°-12°N, 266°-274°W, centered at 11.6°N, 269.5°W. This is at low elevation (-3600 to -3900 m MOLA), is flat (MOLA RMS slope = 0.57°), radar data suggest a smoother surface at decimeter to meter sca…
An XMM-Newton and Chandra Investigation of the Nuclear Accretion in the Sombrero Galaxy (NGC 4594)
Pellegrini, S.; Baldi, A.; Fabbiano, G. +1 more
We present an analysis of the XMM-Newton and Chandra ACIS-S observations of the LINER nucleus of the Sombrero galaxy, and we discuss possible explanations for its very sub-Eddington luminosity by complementing the X-ray results with high angular resolution observations in other bands. The X-ray investigation shows a hard (Γ=1.89) and moderately ab…
How many Hipparcos Variability-Induced Movers are genuine binaries?
Makarov, V. V.; Jorissen, A.; Pourbaix, D. +3 more
Hipparcos observations of some variable stars, and especially of long-period (e.g. Mira) variables, reveal a motion of the photocenter correlated with the brightness variation (variability-induced mover - VIM), suggesting the presence of a binary companion. A re-analysis of the Hipparcos photometric and astrometric data does not confirm the VIM so…
An XMM-Newton study of the hard X-ray sky
Cappi, M.; Piconcelli, E.; Dadina, M. +2 more
We report on the spectral properties of a sample of 90 hard X-ray selected serendipitous sources detected in 12 XMM-Newton observations with 1 <≈F2-10simlt 80 x 10-14 erg cm-2 s-1. Approximately 40% of the sources are optically identified with 0.1 <~ z<~ 2 and most of them are classified as broa…
A Multiwavelength Study of the High-Field Magnetic White Dwarf EUVE J0317-85.5 (=RE J0317-853)
Vennes, Stéphane; Christian, D. J.; Wickramasinghe, D. T. +3 more
We present optical and ultraviolet photometry and spectroscopy and optical circular spectropolarimetry of the ultramassive, rapidly rotating, high-field magnetic white dwarf EUVE J0317-85.5. From the combined data sets, we establish an ephemeris for the photometric, spectroscopic, and polarimetric variations with a spin period of 725.7277 s, the f…
New Light on the Stellar Populations in I Zw 18: Deep Near-Infrared Imaging
Hunt, Leslie K.; Thuan, Trinh X.; Izotov, Yuri I.
We present deep JHK images of I Zw 18, the most metal deficient blue compact dwarf galaxy known, and analyze them in conjunction with archival Hubble Space Telescope/Wide Field Planetary Camera 2 optical images. To investigate the stellar populations, we have divided the main body of I Zw 18 into eight regions and fitted the optical, near-infrared…