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X-ray and radio observations of the activation stages of an X-class solar flare
Hudson, H. S.; Karlický, M.; Fárník, F. +1 more
We report interesting developments prior to the impulsive phase of an X-class solar flare that occurred on September 24, 2001. Our multiwavelength study makes use of X-ray data from the Yohkoh satellite, the Ondřejov radio spectral observations in the decimetric band, and the new Hard X-Ray Spectrometer instrument (HXRS) on board the MTI satellite…
Minor axis kinematics of 19 S0-Sbc bulges
Peletier, R. F.; Falcón-Barroso, J.; Vazdekis, A. +1 more
We present minor axis kinematic profiles for a well-studied sample of 19 early- to intermediate-type disk galaxies. We introduce, for the first time, the use of single-burst stellar population (SSP) models to obtain stellar velocities, velocity dispersions and higher order Gauss-Hermite moments (h3, h4) from galaxy spectra in…
SPI measurements of Galactic 26Al
Strong, A. W.; Knödlseder, J.; von Kienlin, A. +8 more
The precision measurement of the 1809 keV gamma-ray line from Galactic 26Al is one of the goals of the SPI spectrometer on INTEGRAL with its Ge detector camera. We aim for determination of the detailed shape of this gamma-ray line, and its variation for different source regions along the plane of the Galaxy. Data from the first part of …
The open cluster distance scale. A new empirical approach
Salaris, M.; Kilkenny, D.; Percival, S. M.
We present new BV(RI)C photometry for a sample of 54 local G and K stars with accurate Hipparcos parallaxes in the metallicity range -0.4 <= [Fe/H] <= +0.3. We use this sample to develop a completely model-independent main sequence (MS) fitting method which we apply to 4 open clusters - the Hyades, Praesepe, the Pleiades and NGC 2…
The Crab pulsar and its red knot in the near-infrared
Sollerman, J.
We present near-infrared observations obtained with ISAAC on the VLT of the Crab pulsar and its environment. Photometry of the pulsar in Js, H and Ks shows the pulsar spectrum to extend fairly smoothly from the UV/optical regime. PSF subtraction of the pulsar allows us to study its immediate neighborhood in some detail. In pa…
XMM-Newton observations of the Seyfert 1 galaxy NGC 3227
Gondoin, P.; Orr, A.; Lumb, D. +1 more
We report on an XMM-Newton observation of the Seyfert 1 galaxy NGC 3227 performed in November 2000. The observed X-ray spectrum above 4 keV is well fitted by a hard power law continuum (Gamma ~ 1.5) and an absorption edge at 7.6 keV. An Fe K emission line with an equivalent width of 213 eV is detected at 6.4 keV. The line is narrow suggesting cont…
Long-term monitoring of active stars. X. Photometry collected in 1994
Messina, S.; Rodonò, M.; Cutispoto, G.
As part of an extensive program focused on the global properties and evolution of active stars, high-precision UBV(RI)_c and UBV photometry of 18 selected stars is presented. UBV(RI)_c observations were collected at the European Southern Observatory over the intervals 21-28 September 1994 and 25 November-05 December 1994. Additional UBV photometry…
INTEGRAL observations of SS433, a supercritically accreting microquasar with hard spectrum\thanks
Sunyaev, R. A.; Postnov, K. A.; Cherepashchuk, A. M. +3 more
Observations of SS433 by INTEGRAL carried out in March-May 2003 are presented. SS433 is evidently detected on the INTEGRAL images of the corresponding sky region in the energy bands 25-50 and 50-100 keV. The precessional variability of the hard X-ray flux is clearly seen. The X-ray eclipse caused by the binary orbital motion is also detected. A po…
Chandra LETGS and XMM-Newton observations of NGC 4593
Kaastra, J. S.; Behar, E.; Sako, M. +6 more
In this paper, we analyze spectra of the Seyfert 1 galaxy NGC 4593 obtained with the Chandra Low Energy Transmission Grating Spectrometer (LETGS), the Reflection Grating Spectrometer (RGS) and the European Photon Imaging Camera's (EPIC) onboard of XMM-Newton. The two observations were separated by ~ 7 months. In the LETGS spectrum we detect a high…
On variation of the latitudinal structure of the solar convection zone
Thompson, M. J.; Antia, H. M.; Chitre, S. M.
The latitudinal sound-speed structure of the Sun's convection zone gives insight into the physical processes occurring there, specifically the cellular convection and possibly the presence of magnetic fields. Using helioseismic data from the GONG network and MDI instrument on SOHO, we map the latitudinal acoustic structure of the convection zone f…