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361.
The data of Paper I (Doddet al., 1986), representing a catalogue of parameters measured for bright galaxies in field 444 of the Southern Sky Survey, are examined in a search for non-random effects. A global trend of bimodal alignment of galaxies in this field is found. This effect is present even for galaxies of large apparent ellipticity (e0.5) and is interpreted as revealing a real physical phenomenon on the large scale in this field. Analysis of nearest neighbouring pairs of galaxies reveals evidence also for small-scale interactions. The difference in apparent ellipticities between close pairs is larger than would be expected if the galaxies were randomly distributed. Nearest neighbouring galaxies also show a strong preference to be aligned with their major axes parallel. The results are discussed with regard to theories for galaxy formation. 相似文献
362.
Hart JF 《The Journal of geography》1986,85(5):201-211
"This paper explores four selected facets of the geography of population in the [U.S.] Midwest that are related to the movement of people: (1) the spread of occupance across the land; (2) the growth of the population of counties once they had been occupied; (3) the distribution of the foreign-born population; and (4) the distribution of retired people who have migrated after they have retired." 相似文献
363.
F. D'Antona 《Astrophysics and Space Science》1985,112(2):361-365
Recent computations (D'Antona and Mazzitelli, 1982), together with the general scheme of evolution of cataclysmic binaries (CBs), lead to conclude that the secondaries in those CBs having periods shorter than 4.5 hr have a large3He content in the envelope, ranging from 10–4 (P=4.5 hr) to >2×10–3 (P=3 hr) in mass fraction, if the nova systems have an age of some billion years. The consequence on the frequency of novae outbursts is shortly examined. If lithium is produced by galactic novae, the7Li content of old disk stars should be very close to the Population II content.Presented at the 5th European Workshop on White Dwarfs, Kiel, 1984. 相似文献
364.
Absolute masses for W Ursae Majoris and Algol-type close binaries can be determined from their parallax, if observed, and the relative sizes of the stars and their mass ratio, obtained from a light curve solution. An error propagation study compares the typical order of magnitude of the various terms involved, and shows how accurate parallaxes have to be in order to make the procedure work, i.e., making the parallax term not larger than the combined non-parallax terms, and producing reasonably low mass errors. Some comments are made on the possibilities with respect to the HIPPARCOS program.Communication presented at the International Conference on Astrometric Binaries, held on 13–15 June, 1984, at the Remeis-Sternwarte Bamberg, Germany, to commemorate the 200th anniversary of the birth of Friedrich Wilhelm Bessel (1784–1846). 相似文献
365.
C. Baixeras M. Casas F. Fernandez A. Vidal-Quadras M. Ortega 《Astrophysics and Space Science》1983,96(2):321-331
Elemental abundances of the VH group of cosmic radiation have been measured in the energy interval 250–550 MeV nucl–1 in a balloon exposure at Sioux Falls (South Dakota) of a plastic detector LeXAN stack. The so obtained abundances have been extrapolated to the sources in the frame of the homogeneous model correcting for energy loss. After taking into account solar modulation, the best fit to model values has led to a escape mean free path e = 5E
–0.4 g cm–2, whereE is the energy in GeV nucl–1, forE>1 GeV nucl–1, and a constant e = 5 g cm–2 forE1 GeV nucl–1. When turning to the diffusion model, also including an energy loss term, a diffusion coefficientD=3×1028 cm2 s–1 has been estimated. 相似文献
366.
We examine the possibility that the observed cosmic-ray protons are of primary extragalactic origin. The present \(\bar p\) data are consistent with a primary extragalactic component having \(\bar p\) /p?3.2±0.7 x 10-4 independent of energy. Following the suggestion that most extragalactic cosmic rays are from active galaxies, we propose that most of the observed \(\bar p\) 's are alos from the same sites. This would imply the possibility of destroying the corresponding \(\bar \alpha \) 'sat the source, thus leading to a flux ratio \(\bar \alpha \) /α< \(\bar p\) /p. We further predict an estimate for \(\bar \alpha \) α~10-5, within the range of future cosmic-ray detectors. the cosmological implications of this proposal are discussed. 相似文献
367.
Radio and X-ray observations are presented for three flares which show significant activity for several minutes prior to the main impulsive increase in the hard X-ray flux. The activity in this ‘pre-flash’ phase is investigated using 3.5 to 461 keV X-ray data from the Solar Maximum Mission, 100 to 1000 MHz radio data from Zürich, and 169 MHz radio-heliograph data from Nançay. The major results of this study are as follows:
- Decimetric pulsations, interpreted as plasma emission at densities of 109–1010 cm?3, and soft X-rays are observed before any Hα or hard X-ray increase.
- Some of the metric type III radio bursts appear close in time to hard X-ray peaks but delayed between 0.5 and 1.5 s, with the shorter delays for the bursts with the higher starting frequencies.
- The starting frequencies of these type III bursts appear to correlate with the electron temperatures derived from isothermal fits to the hard X-ray spectra. Such a correlation is expected if the particles are released at a constant altitude with an evolving electron distribution. In addition to this effect we find evidence for a downward motion of the acceleration site at the onset of the flash phase.
- In some cases the earlier type III bursts occurred at a different location, far from the main position during the flash phase.
- The flash phase is characterized by higher hard X-ray temperatures, more rapid increase in X-ray flux, and higher starting frequency of the coincident type III bursts.
368.
Energy is stored when the force-free magnetic field in an active region departs from a potential field, the departure showing up as a shear in the field. As soon as the field untwists, energy will be released to produce flares. Based on this idea, we derived an analytical solution of the equation of force-free field under the assumption of a constant force-free factor, and found expressions for seven important quantities for quadrupolar sunspots: the magnetic energy of the twisted field, that of potential field, the extractable free energy ΔM, the magnetic flux, the total current, the force-free factor and the field decay factor, in terms of three observables: the field intensity, the twist angle and the distance between two spots of the same polarity. The expression for ΔM can be useful in solar prediction work. For the active region of August, 1972, we found ΔM up to 6 × 1032 erg, sufficient to supply the energy of the observed flare activity. Observations of this active region are in good general agreement with our theoretical expectations: in the entire twisting of the quadrupolar sunspot group, each spot assumes the form of a complete spiral in the clockwise direction for each of the four spots. 相似文献
369.
We have investigated numerically how a temperature difference between electrons and protons is produced in a flaring loop by adopting a one-fluid, two-temperature model instead of a single-temperature model. We have treated a case in which flare energy is released in the form of heating of electrons located in the top part of the loop.In this case, a large temperature difference (T
e/T
p 10) appears in the corona in the energy-input phase of the flare. When the material evaporated from the chromosphere fills the corona, the temperature difference in the loop begins to shrink rapidly from below. Eventually, in the loop apex, the proton temperature exceeds the electron temperature mainly due to cooling of the electrons by conduction down the loop and heating of the protons by compression of the ascending material. In the late phase of the flare (t 15 min from the flare onset), the temperature difference becomes less than 2% of the mean temperature of electrons and protons at every point in the loop. 相似文献
370.
The Culgoora radioheliograph has been modified for observing at 327.4 MHz, which is in addition to the three frequencies (43.25, 80, and 160 MHz) previously available. At the new frequency the array beamwidth is 56, which represents the highest resolution yet available for metre-wavelength solar mapping.At 327.4 MHz the sources of radio emission are mainly in the lowest layers of the corona. Some preliminary four-frequency observations have been made of type I storms. It is found that the source size generally decreases with increasing observing frequency. This result confirms earlier suggestions that the sources of both type I and type III emission are contained in structures whose boundaries diverge outwards in the corona. 相似文献