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An XMM-Newton observation of the multiple system HD 167971 (O5-8V + O5-8V + (O8I)) and the young open cluster NGC 6604
Blomme, R.; Rauw, G.; De Becker, M. +3 more
We discuss the results of two XMM-Newton observations of the open cluster NGC 6604 obtained in April and September 2002. We concentrate mainly on the multiple system HD 167971 (O5-8V + O5-8V + (O8I)). The soft part of the EPIC spectrum of this system is thermal with typical temperatures of about 2 × 106 to 9 × 106 K. The natu…
Statistics of high-altitude and high-latitude O+ ion outflows observed by Cluster/CIS
Lundin, R.; Yamauchi, M.; Nilsson, H. +8 more
The persistent outflows of O+ ions observed by the Cluster CIS/CODIF instrument were studied statistically in the high-altitude (from 3 up to 11 RE) and high-latitude (from 70 to ~90 deg invariant latitude, ILAT) polar region. The principal results are: (1) Outflowing O+ ions with more than 1keV are observed above …
The very low-mass population of the Corona Australis and Chamaeleon II star forming regions
Eislöffel, J.; López Martí, B.; Mundt, R.
We present the results of a deep optical survey in the Corona Australis and Chamaeleon II star forming regions. Our optical photometry is combined with available near- and mid-infrared photometry to identify very low-mass candidate members in these dark clouds. In our Chamaeleon II field, only one object exhibits clear Hα emission, but the discrep…
Far Ultraviolet Spectroscopic Explorer Observations of the Symbiotic Star AG Draconis
Young, P. R.; Dupree, A. K.; Espey, B. R. +2 more
Spectra of the bright symbiotic star AG Draconis (BD +67°922) in the wavelength range 905-1187 Å obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) are presented. The spectra show a number of narrow, nebular emission lines, together with a uniform continuum from the hot component of the system, and numerous interstellar absorption lin…
A possible bright blue supernova in the afterglow of GRB 020305
Nugent, P.; Fynbo, J. P. U.; Gorosabel, J. +8 more
We report on ground-based and HST(+STIS) imaging of the afterglow and host galaxy of the Gamma-Ray Burst (GRB) of March 5, 2002. The GRB occurred in a R=25.17 ± 0.14 galaxy, which apparently is part of an interacting system. The lightcurve of the optical afterglow shows a rebrightening, or at least a plateau, 12 16 days after the gamma-ray event. …
RR Lyrae stars: kinematics, orbits and z-distribution
de Boer, K. S.; Maintz, G.
RR Lyrae stars in the Milky Way are good tracers to study the kinematic behaviour and spatial distribution of older stellar populations. A recently established well documented sample of 217 RR Lyr stars with V<12.5 mag, for which accurate distances and radial velocities as well as proper motions from the Hipparcos and Tycho-2 catalogues are ava…
An X-Ray View of Weak-Line Radio Galaxies/LINERs
Gliozzi, Mario; Sambruna, Rita M.; Rinn, Alexander S.
We present X-ray observations of nine weak-line radio galaxies (WLRGs), optically classified as confirmed or possible LINERs. The data were taken from the Chandra, XMM-Newton, and BeppoSAX archives. The Chandra images typically show complex X-ray morphologies, with hard (2-10 keV) point sources embedded in diffuse soft (0.3-2.0 keV) emission in al…
New runaway OB stars with HIPPARCOS
Mdzinarishvili, T. G.; Chargeishvili, K. B.
A Monte Carlo method for detection of runaway OB stars from observational data is proposed. 61 runaway OB star candidates have been detected by an analysis of Hipparcos proper motions. The peculiar tangential and total transverse velocities have been determined for these stars. A list of the detected runaway star candidates is presented. The evide…
Kinetic Helicity Density in Solar Subsurface Layers and Flare Activity of Active Regions
Howe, R.; Komm, R.; Hill, F. +2 more
We search for a relation between subsurface flows below active regions and flare events occurring in those regions. For this purpose, we use a ring-diagram analysis to determine the subsurface flows from high-resolution Global Oscillation Network Group (GONG) and Michelson Doppler Imager (MDI) data and derive the kinetic helicity as a measure of t…
The influence of gravitational lensing on the spectra of lensed quasi-stellar objects
Popović, L. Č.; Chartas, G.
We consider the influence of (milli/micro)lensing on the spectra of lensed quasi-stellar objects (QSOs). We propose a method for the observational detection of microlensing in the spectra of lensed QSOs and apply it to the spectra of three lensed QSOs (PG 1115+080, Q1413+117 and Q0957+561) observed with the Hubble Space Telescope. We find that the…