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991.
Yu Zhang Fenghui Zhang Zhanwen Han Jinzhong Liu 《Astrophysics and Space Science》2010,329(1-2):255-260
Spectra synthesis is entering a new era with the availability of large and high-quality spectroscopic data and full spectrum fitting methods. Establishing the reliability whether the STARLIGHT code (a full spectrum fitting code, Cid Fernandes et al. (Mon. Not. R. Astron. Soc. 358:363, 2005)) is suitable to study the properties of various types of galaxies is vital to galaxy study. In testing this possibility, Galactic globular clusters (GCs) provide an excellent medium. Taking the 40 Galactic GCs as an example in our work, we analyze their integrated spectra from Schiavon et al. (Astrophys. J. Suppl. 160:163, 2005) and obtain their mixtures of stellar populations that best represents their composite nature. Through analyzing the distributions of stellar ages and metallicities respectively, we find that the stellar metallicity distribution is centered at a low value and the stellar age distribution is very scattered. To compare with the literature, we also calculate the light-weighted ages and metallicities of GCs, and we find that the light-weighted metallicities agree with the literature, while the light-weighted ages are lower than those of the literature. This demonstrates that STARLIGHT can be used to obtain the metallicities of GCs. 相似文献
992.
P. Pappa Kalaivani S. Umapathy A. Shanmugaraju O. Prakash 《Astrophysics and Space Science》2010,330(2):237-242
We have studied the characteristics of coronal mass ejections (CMEs) associated with Deca-Hectometric (DH) type II radio bursts (1–14 MHz) in the interplanetary medium during the year 1997–2005. The DH CMEs are divided into two parts: (i) DH CMEs (All) and (ii) DH CMEs (Limb). We found that 65% (177/273) of all events have the speed >900 km?s?1 and the remaining 35% (96/273) events have the speed below 900 km?s?1. The average speed of all and limb DH CMEs are 1230 and 1288 km?s?1, respectively, which is nearly three times the average speed of general population of CMEs (473 km?s?1). The average widths of all and limb DH CMEs are 105° and 106°, respectively, which is twice the average width (52°) of the general population of CMEs. We found a better correlation between the speed and width of limb DH CMEs (R=?0.61) than all DH CMEs (R=?0.53). Only 28% (177/637) of fast >900 km?s?1 general population of CMEs are reported with DH type II bursts counterpart. The above results gives that the relation between the CME properties is better for limb events. 相似文献
993.
994.
995.
Reba M. Bandyopadhyay K.S. Wood P. Hertz M.N. Lovellette P.S. Ray M.T. Wolff B. Giebels E.D. Bloom 《Astrophysics and Space Science》2001,276(1):23-24
We present first results from a monitoring campaign of GRS 1915+105 undertaken with the USA X-ray timing experiment on the ARGOS satellite. A variety of behaviour has been observed, ranging from low, steady X-ray emission to rapid quasi-periodic flaring on timescales of approximately 10–120 seconds. 相似文献
996.
Ken Ebisawa Aya Kubota Tsunefumi Mizuno Piotr Życki 《Astrophysics and Space Science》2001,276(1):11-14
The Ultra-luminous Compact X-ray Sources (ULXs)in nearby spiral galaxies and the Galactic super-luminaljet sources sharethe common spectral characteristic that they haveextremely high disk temperatures which cannot be explainedin the framework of the standard accretion disk modelin the Schwarzschild metric. We have calculated an extreme Kerr disk model to examine if the Kerr disk model can instead explain the observed `too hot' accretion disk spectra.We found that the Kerr disk spectrum becomes significantly hardercompared to the Schwarzschild disk only when the disk is highlyinclined.For super-luminal jet sources, which are known to beinclined systems, the Kerr disk model may thuswork if we choose proper values for the black hole angular momentum. For the ULXs, however, the Kerr disk interpretation will be problematic,as is is highly unlikely that their accretion disks are preferentiallyinclined. 相似文献
997.
T. Wiegelmann S. K. Solanki J. M. Borrero H. Peter P. Barthol A. Gandorfer V. Martínez Pillet W. Schmidt M. Knölker 《Solar physics》2013,283(2):253-272
Observations with the balloon-borne Sunrise/Imaging Magnetograph eXperiment (IMaX) provide high spatial resolution (roughly 100 km at disk center) measurements of the magnetic field in the photosphere of the quiet Sun. To investigate the magnetic structure of the chromosphere and corona, we extrapolate these photospheric measurements into the upper solar atmosphere and analyze a 22-minute long time series with a cadence of 33 seconds. Using the extrapolated magnetic-field lines as tracer, we investigate temporal evolution of the magnetic connectivity in the quiet Sun’s atmosphere. The majority of magnetic loops are asymmetric in the sense that the photospheric field strength at the loop foot points is very different. We find that the magnetic connectivity of the loops changes rapidly with a typical connection recycling time of about 3±1 minutes in the upper solar atmosphere and 12±4 minutes in the photosphere. This is considerably shorter than previously found. Nonetheless, our estimate of the energy released by the associated magnetic-reconnection processes is not likely to be the sole source for heating the chromosphere and corona in the quiet Sun. 相似文献
998.
Under the assumption that the photospheric quiet Sun magnetic field is turbulent, the cancellation function has previously been used to estimate the true, resolution-independent mean, unsigned vertical flux 〈|B z |〉true. We show that the presence of network elements, noise, and seeing complicate the measurement of accurate cancellation functions and their power law exponents κ. Failure to exclude network elements previously led to estimates that were too low for both the cancellation exponent κ and 〈|B z |〉true. However, both κ and 〈|B z |〉true are overestimated due to noise in magnetograms. While no conclusive value can be derived with data from current instruments, our Hinode/SP results of κ?0.38 and 〈|B z |〉true?270 gauss can be taken as upper bounds. 相似文献
999.
1000.
HAN Liang LI Bo SONG Tao TONG Lian-jun 《中国地理科学(英文版)》2006,16(2):148-153
1INTRODUCTION The circular-economyisan efficient resources metabolic process, based on principles of ecology and system engi- neering.Withcoupledstructure andthe complex ecolo- gical and economic evolution, it has the characteristics of overall integrity, coordination, and circulation (WANG, 2005). Compared with the traditionalecono- mic model, the circular-economy requires the technical model of production process to be changed from the opening flow pattern that is "resourcesconsumption… 相似文献