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Power-law spectra f(E)∝E?2.7 of < 40 keV suprathermal ions within ~107 km of propagating interplanetary shocks are explained by diffusive scattering near a plane shock. The theory fits the 25 November 1977 event with a mean free path perpendicular to the shock with is 0.01 AU in front of the shock and less than .0003 AU behind it, for 1 keV ions. The theory predicts a steepening spectrum at higher energies, of the form f(v)∝v?4exp(??λdv/ur) where u = (ΔV)2/2VW depends on the plasma velocity jump ΔV and the plasma speed VW and mean free path λ in front of the shock  相似文献   

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We note that far-from-equilibrium chemical systems can respond very sensitively to gravity. The response could be in selection of possible structures or in the formation of propagating bands. In these cases the sensitivity is characterized by the factor (Eg/kT)1n, where n=2 or 3, Eg the interaction energy, k the Boltzmann constant and T, the temperature. Also, taking the thermodynamic fluctuations into account, we obtain the theoretical limit for the minimum field strength measurable by such systems.  相似文献   

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Using the bulge data from AGN image decomposition with ground-based observations, we calculate the ratios of the central supermassive black hole mass(SMBH) to the Bulge mass (Mbh/MbulgeMbh/Mbulge) in a sample of X-ray selected AGNs, including 15 Narrow-line Seyfert 1 galaxies (NLS1s) and 18 broad-line Seyfert 1 galaxies (BLS1s). We found that the mean value of log(Mbh/Mbulge)log(Mbh/Mbulge) is -3.81±0.11-3.81±0.11 for 15 NLS1s, and -2.91±0.13-2.91±0.13 for 18 BLS1s, showing the lower Mbh/MbulgeMbh/Mbulge in NLS1s relative to BLS1s. The calculation shows that the Bulge mass from the host image decomposition in NLS1s is statistically smaller than that from Hubble-type correction method, and a linear mass relation is suggested for NLS1s and a nonlinear mass relation for BLS1s. The studying of host galaxies with ground-based observations strongly limited by the atmospheric seeing. We need to do the decomposition of host images for NLS1s with Hubble Space Telescope observation in the future.  相似文献   

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Very Large Array (V.L.A.) measurements at 20 cm wavelength map emission from coronal loops with second-of-arc angular resolution at time intervals as short as 3.3 seconds. The total intensity of the 20 cm emission describes the evolution and structure of the hot plasma that is detected by satellite X-ray observations of coronal loops. The circular polarization of the 20 cm emission describes the evolution, strength and structure of the coronal magnetic field. Preburst heating and magnetic changes that precede burst emission on time scales of between 1 and 30 minutes are discussed. Simultaneous 20 cm and soft X-ray observations indicate an electron temperature Te 2.5 × 107 K and electron density Ne 1010 cm?3 during preburst heating in a coronal loop that was also associated with twisting of the entire loop in space. We also discuss the successive triggering of bursts from adjacent coronal loops; highly polarized emission from the legs of loops with large intensity changes over a 32 MHz change in observing frequency; and apparent motions of hot plasma within coronal loops at velocities V > 2,000 kilometerspersecond.  相似文献   

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Doppler and ranging measurements using the radio signal of the GIOTTO spacecraft were taken before, during, and after the encounter with Comet Halley on 1314 March 1986. The spacecraft velocity was found to decrease by a total of 23.3 cm s?1 due to impacting gas and (primarily) dust in the cometary atmosphere. A preliminary dust production rate Qd ? 10 × 103kg s?1 is found to be consistent with this deceleration. Power spectra of the carrier phase fluctuations reveal an increase in level and a flattening of the spectrum just prior to encounter, presumably associated with the enhanced dust impact rate. Finally, simulated Doppler time profiles are computed using the radial dependence of plasma density observed by the GIOTTO in situ investigations. It is shown that the cometary electron content profile would have been clearly seen if a dual-frequency downlink radio configuration had been available at encounter.  相似文献   

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The Vega-1 and Vega-2 wave and plasma measurements performed on 6 and 9 March 1986 in the environment of comet Halley present similar characteristics. Field spectral intensity of up to 5 mVm?1Hz?12 at 300 Hz is measured at closest approach; enhanced signals are detected in the whistler mode and in the vicinity of the lower hybrid resonance frequency within respective average distances of 130,000 km and 60,000 km from the nucleus. The plasma density rises from 100 cm?3 at 200,000 km up to 3000 cm?3 at 25,000 km. The spacecraft potential is of the order of +3 V beyond a distance of 200,000 km and decreases to about +0.5 V at 8,000 km.  相似文献   

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We present medium resolution near-infrared host galaxy spectra of low redshift quasars, PG 0844+3490844+349 (z = 0.064), PG 1226+0231226+023 (z = 0.158), and PG 1426+0151426+015 (z = 0.086). The observations were done by using the Infrared Camera and Spectrograph (IRCS) at the Subaru 8.2 m telescope. The full width at half maximum of the point spread function was about 0.3 arcsec by operations of an adaptive optics system, which can effectively resolve the quasar spectra from the host galaxy spectra. We spent up to several hours per target and developed data reduction methods to reduce the systematic noises of the telluric emissions and absorptions. From the obtained spectra, we identified absorption features of Mg I (1.503 μm), Si I (1.589 μm) and CO (6-3) (1.619 μm), and measured the velocity dispersions of PG 0844+3490844+349 to be 132 ± 110 km s−1 and PG 1426+0151426+015 to be 264 ± 215 km s−1. By using an MBH–σMBHσ relation of elliptical galaxies, we derived the black hole (BH) mass of PG 0844+3490844+349, log(MBH/M)=7.7±5.5log(MBH/M)=7.7±5.5 and PG 1426+015,log(MBH/M)=9.0±7.51426+015,log(MBH/M)=9.0±7.5. These values are consistent with the BH mass values from broad emission lines with an assumption of a virial factor of 5.5.  相似文献   

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