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A new intrinsic-colour calibration is presented for the uvby-β photometric system, making use of re-calibrated Hipparcos parallaxes and published reddening maps. This new calibration for , our Eq. (1), has been based upon stars with in the photometric catalogues of Schuster and Nissen (1988), Schuster et al., 2004, Schuster et al., 2006, provides a small dispersion, , and has a positive “standard” coefficient, which is not too different from the coefficients of Crawford (1975a, +1.11) and of Olsen (1988, +1.34). For 61 stars with spectra from CASPEC, UVES/VLT, and FIES/NOT databases, without detectable Na I lines, the average reddening value shows that any zero-point correction to our intrinsic-colour equation must be minuscule. 相似文献
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Higher-order gyroresonant acceleration of electrons by superluminous (AKR) wave-modes 总被引：1，自引：0，他引：1
《Planetary and Space Science》2007,55(10):1257-1271
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《New Astronomy》2015
Detailed photoionization of ground and many excited states with autoionizing resonances of neutral Ti are presented. Ti I with 22 electrons forms a large number of bound states, the present work finds a total of 908 bound states with n 10 and . Photoionization cross sections () for all these bound states have been obtained. Calculations were carried out in the close-coupling R-matrix method using a wave function expansion that included 36 states of core ion Ti II. It is found that the resonances enhance the low energy region of photoionization of the ground and low lying excited states. The resonant features will increase the opacity, as expected of astrophysical observation, and hence play important role in determination of abundances in the elements in the astronomical objects. The excited states also show prominent structures of Seaton or photo-excitation-of-core resonances. 相似文献
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Version 2.0 of CRPropa [CRPropa is published under the 3rd version of the GNU General Public License (GPLv3). It is available, together with a detailed documentation of the code, at https://crpropa.desy.de.] is public software to model the extra-galactic propagation of ultra-high energy nuclei of atomic number through structured magnetic fields and ambient photon backgrounds taking into account all relevant particle interactions. CRPropa covers the energy range where A is the nuclear mass number. CRPropa can also be used to track secondary γ-rays and neutrinos which allows the study of their link with the charged primary nuclei – the so called multi-messenger connection. After a general introduction we present several sample applications of current interest concerning the physics of extragalactic ultra-high energy radiation. 相似文献
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《Planetary and Space Science》2007,55(11):1502-1508
We investigate the dynamics of magnetospheric ions during transient reconfigurations of Mercury's magnetotail. At Earth, numerous observations during similar events reveal a prominent energization (up to the hundreds of keV range) of heavy ions originating from the topside ionosphere. This energization likely results from a resonant nonadiabatic interaction with the electric field that is induced by dipolarization of the magnetic field lines, the time scale of this reconfiguration being comparable to the heavy ion cyclotron period. The question then arises whether such an energization may occur at Mercury. Using single-particle simulations in time-varying electric and magnetic fields, we show that prominent nonadiabatic heating is obtained for ions with small mass-to-charge ratios (e.g., ). As for heavy ions (e.g., ) that have cyclotron periods well above the time scale of the magnetotail reconfiguration (several seconds), a weaker energization is obtained. The resonant heating mechanism that we examine here may be of importance for solar wind protons that gain access to the inner hermean magnetotail as well as for light ions of planetary origin that directly feed the near-Mercury plasma sheet. 相似文献
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J.R. Kristiansen G. La Vacca L.P.L. Colombo R. Mainini S.A. Bonometto 《New Astronomy》2010,15(7):609-613
We consider cosmological models with dynamical dark energy (dDE) coupled to cold dark matter (CDM), while simultaneously allowing neutrinos to be massive. Using a MCMC approach, we compare these models with a wide range of cosmological data sets. We find a strong correlation between this coupling strength and the neutrino mass. This correlation persists when BAO data are included in the analysis. We add then priors on mass from particle experiments. The claimed detection of mass from the Heidelberg–Moscow neutrinoless double- decay experiment would imply a 7– detection of CDM–DE coupling. Similarly, the detection of mass from coming KATRIN tritium decay experiment will imply a safe detection of a coupling in the dark sector. Previous attempts to accommodate cosmic phenomenology with such possible mass data made recourse to a eoS. We compare such an option with the coupling option and find that the latter allows a drastic improvement. 相似文献