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991.
Hans Zinnecker 《Astrophysics and Space Science》2002,281(1-2):147-157
In this brief report we summarise the most important points raised in the course of a two-hour evening discussion session
on the above topic, organised by the author. Major questions that were debated included the universality of the IMF, the history
of the star formation rate in the solar neighorhood, the star formation efficiency in molecular clouds, and the role of triggered
star formation. The issue of a threshold gas surface density for star formation to occur was also critically discussed.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
992.
D. I. Podolsky 《Astronomy Letters》2002,28(7):434-437
The recently detected accelerated expansion of the Universe is related to the existence of a new type of matter called the Λ field or quintessence. Constraints were obtained on its equation of state from the absence of clustering of this matter on scales much smaller than the cosmological horizon. The question of how these constraints affect the possibility of fitting the accelerated expansion by such cosmological models as the Chaplygin gas model is discussed. 相似文献
993.
994.
Mock 2dF and SDSS galaxy redshift surveys 总被引:1,自引:0,他引:1
995.
996.
It is shown that the lists of Shakhbazian Compact Galaxy Groups (SCGGs) are not complete. The number of the detected groups in the strip between b = ±30° and b = ±20° is by four to five times smaller than expected. The most probable reason is that during the search for SCGGs it was hard to distinguish images of compact galaxies from that of stars on the POSS prints in dense areas of the sky at lower galactic latitudes. There is some deficit of the detected groups between 60° and 40° of the north galactic latitudes. The surface density of SCGGs in the southern galactic hemisphere between b = −50° and b = −30° is by about three times less than it is expected. Obviously, the southern sky has not been searched properly. The list of Hickson's groups is complete down to galactic latitude ±30°. However, some excess of HCGs is found in the southern hemisphere, where the surface density of the found groups is by about two times higher than that of in the northern hemisphere. 相似文献
997.
从中国目视资料分析1998年狮子座流星雨 总被引:3,自引:0,他引:3
本文分析了1998 年狮子座流星雨的一部分中国目视资料。资料启示:1998 年狮子座流星雨来自两股不同组成的流星体颗粒的不均匀混合流。按照这种观点进行了以这些目视资料为基础的计算,从而解释了目视观测与雷达观测所得结果之间的矛盾。 相似文献
998.
999.
V.Kolokotronis M.Plionis P.Coles S.Borgani 《Monthly notices of the Royal Astronomical Society》1998,295(1):19-32
We investigate the sampling and dipole convergence properties of flux-limited samples of mock X-ray clusters in relation to their underlying 'parent' cluster distribution. To this purpose, we resort to numerical simulations of the cluster distribution and extract samples resembling the main observational features of X-ray selected cluster samples. The flux-limited samples, being quite sparse, underestimate the amplitude of the 'parent' cluster dipole by ≈ 15 per cent on average for Local Group-like observers. However, the general shapes of their dipole amplitude profiles are in relatively good agreement. We also calculate the expected contribution of clusters, selected according to the relevant criteria, to the soft (i.e. 0.1–2.4 keV) extragalactic X-ray background (XRB), using the ESO Key Project X-ray luminosity function, assuming a flat universe with vanishing cosmological constant. We obtain a value of about 10 per cent of the observed XRB flux. 相似文献
1000.
A new model for gamma-ray pulsars presented by Higgins & Henriksen is applied to the cases of the seven known gamma-ray pulsars. Those pulsars that are not presently observed in gamma-rays, but are candidates for observation by the next generation of gamma-ray telescopes, are discussed. The case of millisecond pulsars is discussed, and it is shown that these objects should radiate at detectable levels, in opposition to the predictions of other gamma-ray pulsar models. 相似文献