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Several Active Galactic Nuclei (AGNs) have been reported to harbor fast outflows exceeding 10,000 km?s?1, which are detected mostly in their low-resolution CCD X-ray spectra. Only few, however, were detected with high-resolution grating spectrometers. Most of the grating detected outflows have been observed multiple times. In these cases, the absorption spectrum changes are indicating that variability is common among these high-velocity winds. In this paper we revisit the grating observations of PG?1211+143, and PDS?456, and report preliminary results on 4C?74.26. We discuss the spectral variability of the first two sources and its implications to the outflows. 相似文献
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Litvak ML Mitrofanov IG Barmakov YN Behar A Bitulev A Bobrovnitsky Y Bogolubov EP Boynton WV Bragin SI Churin S Grebennikov AS Konovalov A Kozyrev AS Kurdumov IG Krylov A Kuznetsov YP Malakhov AV Mokrousov MI Ryzhkov VI Sanin AB Shvetsov VN Smirnov GA Sholeninov S Timoshenko GN Tomilina TM Tuvakin DV Tretyakov VI Troshin VS Uvarov VN Varenikov A Vostrukhin A 《Astrobiology》2008,8(3):605-612
We present a summary of the physical principles and design of the Dynamic Albedo of Neutrons (DAN) instrument onboard NASA's 2009 Mars Science Laboratory (MSL) mission. The DAN instrument will use the method of neutron-neutron activation analysis in a space application to study the abundance and depth distribution of water in the martian subsurface along the path of the MSL rover. 相似文献
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A.J. Blustin G. Branduardi-Raymont E. Behar J.S. Kaastra M.J. Page S.M. Kahn M. Sako K.C. Steenbrugge 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,34(12):2561-2565
We present results from the analysis of an XMM-Newton observation of the Seyfert 1 galaxy NGC 7469, the first high resolution X-ray spectrum of this source. The Reflection Grating Spectrometer (RGS) spectrum has several narrow absorption and emission lines of O, N, C and Ne, originating from gas at a range of ionisation parameters, from log ξ1.6 to log ξ−2 (where ξ has the units erg cm s−1). We demonstrate that the ionisation state of the warm emitter is consistent with that of the high-ionisation phase of the warm absorber, and compare the warm absorber in this object with those in other sources. 相似文献
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I. G. Mitrofanov M. L. Litvak A. B. Varenikov Y. N. Barmakov A. Behar Y. I. Bobrovnitsky E. P. Bogolubov W. V. Boynton K. Harshman E. Kan A. S. Kozyrev R. O. Kuzmin A. V. Malakhov M. I. Mokrousov S. N. Ponomareva V. I. Ryzhkov A. B. Sanin G. A. Smirnov V. N. Shvetsov G. N. Timoshenko T. M. Tomilina V. I. Tret’yakov A. A. Vostrukhin 《Space Science Reviews》2012,170(1-4):559-582
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Patrick Cohendet Ehud Zuscovitch 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(7):23-31
La technologie spatiale s'est progressivement révélée comme un centre de propulsion technologique et économique pour les pays industriels qui ont pris partie dans l'effort de financement du programme spatial. La question que nous devons nous poser est de savoir dans quelle mesure le savoir et l'expérience accumulés lors du processus de production de cette technologie peut servir d'exemple à la forme de propagation du progrès économique pour les pays en voie de développement. 相似文献
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