X-ray flares

Akerib, D. S., et al. [CDMS Collaboration] 2003. New results from the Cryogenic Dark Matter Search experiment, Phys. Rev. D68, 082002 Allanach, B. C., Kraml, S. Porod, W. 2003. Theoretical uncertainties in sparticle mass predictions from computational tools, JHEP 0303, 016 Aschenbach, B., Grosso, N., Porquet, D., Predehl, P. 2004. X-ray flares reveal mass and angular momentum of the Galactic Center black hole. Preprint astro-ph/0401589... 

Leading models for transient heating mechanisms include shock waves, X-ray flares, the X-wind, and partially molten planetesimals. Shock waves have been shown to be able to reproduce the deduced thermal histories of chondrules, yet... 

The ionosphere is subject to sudden changes resulting from solar activity, particularly from solar emptions or flares that are accompanied by intense x-ray emission. The absorption of the x-rays increases the electron density in the D and E layers, so that absorption of radio waves intended for E-layer reflection increases. In this manner, solar flares dismpt long-range, ionospheric bounce communications. 

Although events taking place on the sun, such as sun spots and solar flares, alter the amount of radiation, the alteration is almost entirely in the x-ray and ultraviolet regions and does not affect the amount in the wavelengths reaching the earth s surface. Therefore, the amount of radiation from the sun that can penetrate to the earth s surface is remarkably constant. 

On the other hand, the X-ray intensity in the hard X-ray band (16 - 28 keV) exhibits much less change than those in the soft X-ray band. The first positive detection was on July 4, 1987. It should be mentioned, however, that the epoch when the hard X-ray intensity exceeded the Ginga detection threshold remains somewhat uncertain. This is because the observing condition was unfavorable in May and June, 1987. Since the detection, the intensity in the hard X-ray band has remained almost constant within the statistical uncertainties through December, 1987. In the January flare, the hard X-ray intensity increased simultaneously by a factor of two, which was however much smaller than the factor of increase in the soft X-ray band. 

Satisfactory fit was obtained for all cases. As the result, the intensity of the hard component turned out to be the same for all three spectra within the errors. This implies that the hard component remained essentially constant for more than 200 days. The temperature kT of the soft component is found to be about 10 keV for the spectra A and B but is higher than 50 keV for the spectrum C. The count rate increase in the hard X-ray band (16 - 28 keV) during the January flare (see Fig. 3) is thus interpreted as due to an enhanced contribution of the hardened soft component. The luminosity of the soft component reached 1038 ergs/sec at the flare peak, for the assumed distance of 50 kpc. 

Further evidence for a black hole at the center of the Milky Way comes from the 2001 observation of a X-ray and infrared flares from the Galactic Center Baganoff et al.(2001) Porquet et al.(2003) Genzel et al.(2003b). The flare time scale and intensity can nicely be explained if the flare is produced near a black hole , see, e.g.,]Aschenbach 2004. 

Mrs D has recently been admitted with an episode of acute severe ulcerative colitis. This is her third flare this year. This time she has a 5-day history of bloody diarrhoea with abdominal pain. On average she is opening her bowels seven times a day. She is currently taking mesalazine 800 mg three times daily and prednisolone 20 mg daily. Mrs D also has an elevated temperature of 38°C and a pulse rate of 92 bpm. She is due to have an abdominal X-ray and a stool culture. 

Observations of the Orion nebular cluster by the Chandra X-ray observatory reveal the presence of frequent (one every 6 days), large (up to 0.5 AU), and highly energetic stellar flares (with inferred magnetic fields as large as 3000 G) (Favata et al. 2005). The duration of the flares varies from less than an hour to almost three... 

A wide variety of plasma diagnostic applications is available from the measurement of the relatively simple X-ray spectra of He-like ions [1] and references therein. The n = 2 and n = 3 X-ray spectra from many mid- and high-Z He-like ions have been studied in tokamak plasmas [2-4] and in solar flares [5,6]. The high n Rydberg series of medium Z helium-like ions have been observed from Z-pinches [7,8], laser-produced plasmas [9], exploding wires [8], the solar corona [10], tokamaks [11-13] and ion traps [14]. Always associated with X-ray emission from these two electron systems are satellite lines from lithium-like ions. Comparison of observed X-ray spectra with calculated transitions can provide tests of atomic kinetics models and structure calculations for helium- and lithium-like ions. From wavelength measurements, a systematic study of the n and Z dependence of atomic potentials may be undertaken. From the satellite line intensities, the dynamics of level population by dielectronic recombination and inner-shell excitation may be addressed. 

X-ray spectroscopy has also been applied to the interpretation of solar spectra, which are emitted by solar flares. Now stellar objects are under investigation by X-ray satellites such as Chandra and XMM. Whereas the present X-ray telescopes are medium resolution devices, the next generation (Constellation-X, XEUS) will provide sufficient spectral resolution for detailed analysis. The spectra from distant object usually suffer from low statistics solar flares have low emission time and the observation time of stellar objects is limited. In addition, the electron distribution is not Maxwellian, in general, and some of the spectral lines may be polarized. Therefore, verified theoretical data are of great importance to interpret solar and stellar spectra, where they provide the only source of information on the plasma state. 

Within the last 25 years of X-ray spectroscopy on fusion devices, the theory of He-like ions has been developed to an impressive precision. The spectra can be modeled with deviations not more than 10% on all lines. For the modeling, only parameters with physical meaning and no additional approximation factors are required. Even the small effects due to recombination of H-like atoms, which contribute only a few percent to the line intensity, can be used to explain consistently the recombination processes and hence the charge state distribution in a hot plasma. The measurements on fusion devices such as tokamaks or stellarators allow the comparison to the standard diagnostics for the same parameters. As these diagnostics are based on different physical processes, they provide sensitive tests for the atomic physics used for the synthetic spectra. They also allow distinguishing between different theoretical approaches to predict the spectra of other elements within the iso-electronic series. The modeling of the X-ray spectra of astronomical objects or solar flares, which are now frequently explored by X-ray satellite missions, is now more reliable. In these experiments, the statistical quality of the spectra is limited due to the finite observation time or the lifetime of... 

Analysis of X rays emitted by Eros during a solar flare and observed by NEAR-Shoemaker showed that the asteroid s composition closely resembled that of the chondritic meteorites, which are considered remnants of the early solar system. This has bolstered the theory that the asteroids, too, are primordial leftovers that have never been part of any planet. 

An 8-year-old girl with asthma underwent tonsillectomy and adenoidectomy hemostasis was performed with bismuth-adrenaline paste. A small amount of bismuth was noted in the endotracheal tube before extu-bation, and in the recovery room she developed respiratory difficulty associated with nasal flaring and sternal retraction. A chest X-ray showed aspirated radio-opaque material outlining the tracheobronchial tree and early pulmonary infiltrates. 

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