IS THE CORONA THE SOURCE OF THE EJECTED MATERIAL IN MICROQUASARS?

2010 ◽  
Vol 19 (06) ◽  
pp. 777-782 ◽  
Author(s):  
JEROME RODRIGUEZ ◽  
LIONEL PRAT

Microquasar outbursts are characterized by spectral state transitions. The transitions between states characterized by a hard spectrum and those characterized by a soft spectrum are of particular interest. Besides drastic spectral and timing changes, these transitions often show discrete ejections detectable in the radio domain. The mechanisms giving birth to the ejections, the links with accretion and the exact nature of the ejected material are still largely unknown. We present systematic X–ray spectral analysis prior to the ejection in several microquasars, and show that, in each case, the properties of the corona drastically evolve, while that of the disc remain roughly constant. We intepret this behavior as possibly due to an ejection of the corona at the spectral transition.

2014 ◽  
Vol 444 (1) ◽  
pp. 642-650 ◽  
Author(s):  
H. Marlowe ◽  
P. Kaaret ◽  
C. Lang ◽  
H. Feng ◽  
F. Grisé ◽  
...  

2009 ◽  
Vol 705 (2) ◽  
pp. L109-L112 ◽  
Author(s):  
O. Godet ◽  
D. Barret ◽  
N. A. Webb ◽  
S. A. Farrell ◽  
N. Gehrels

2011 ◽  
Vol 743 (1) ◽  
pp. 6 ◽  
Author(s):  
Mathieu Servillat ◽  
Sean A. Farrell ◽  
Dacheng Lin ◽  
Olivier Godet ◽  
Didier Barret ◽  
...  

2015 ◽  
Vol 67 (5) ◽  
pp. 92 ◽  
Author(s):  
Kazumi Asai ◽  
Tatehiro Mihara ◽  
Masaru Matsuoka ◽  
Mutsumi Sugizaki

2005 ◽  
Vol 432 (1) ◽  
pp. 181-187 ◽  
Author(s):  
E. Meyer-Hofmeister ◽  
B. F. Liu ◽  
F. Meyer

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1153
Author(s):  
Ivan Pavlenko ◽  
Jozef Zajac ◽  
Nadiia Kharchenko ◽  
Ján Duplák ◽  
Vitalii Ivanov ◽  
...  

This article deals with improving the wear resistance of multilayer coatings as a fundamental problem in metal surface treatment, strengthening elements of cutting tools, and ensuring the reliability of machine parts. It aims to evaluate the wear depth for multilayer coatings by the mass loss distribution in layers. The article’s primary purpose is to develop a mathematical method for assessing the value of wear for multilayer steel-based coatings. The study material is a multilayer coating applied to steel DIN C80W1. The research was performed using up-to-date laboratory equipment. Nitrogenchroming has been realized under overpressure in two successive stages: nitriding for 36 h at temperature 540 °C and chromizing during 4 h at temperature 1050 °C. The complex analysis included several options: X-ray phase analysis, local micro-X-ray spectral analysis, durometric analysis, and determination of wear resistance. These analyses showed that after nitrogenchroming, the three-layer protective coating from Cr23C6, Cr7C3, and Cr2N was formed on the steel surface. Spectral analysis indicated that the maximum amount of chromium 92.2% is in the first layer from Cr23C6. The maximum amount of carbon 8.9% characterizes the layer from Cr7C3. Nitrogen is concentrated mainly in the Cr2N layer, and its maximum amount is 9.4%. Additionally, it was determined that the minimum wear is typical for steel DIN C80W1 after nitrogenchroming. The weight loss of steel samples by 25 mg was obtained. This value differs by 3.6% from the results evaluated analytically using the developed mathematical model of wear of multilayer coatings after complex metallization of steel DIN C80W1. As a result, the impact of the loading mode on the wear intensity of steel was established. As the loading time increases, the friction coefficient of the coated samples decreases. Among the studied samples, plates from steel DIN C80W1 have the lowest friction coefficient after nitrogenchroming. Additionally, a linear dependence of the mass losses on the wearing time was obtained for carbide and nitride coatings. Finally, an increase in loading time leads to an increase in the wear intensity of steels after nitrogenchroming. The achieved scientific results are applicable in developing methods of chemical-thermal treatment, improving the wear resistance of multilayer coatings, and strengthening highly loaded machine parts and cutting tools.


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