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Effects of binary interactions on the color evolution of M33

Science China(Physics,Mechanics & Astronomy) 2012年第8期55卷 1505-1509页

作者： KANG XiaoYu ZHANG FengHui ZHANG Yu National Astronomical Observatories Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China

In this work, predictions of the spectral energy distribution from populations of single and binary stars are incorporated into a galactic chemical and color evolution model to explore the significance of the effects of the binary interactions on the color evolution of M33. We first constructed a model without binary interactions, and the model is able to reproduce most of the available observational constraints on the distribution of stellar parameters. We then run simulations with the same set of model parameters but with binary interactions considered. By comparing the results for the populations with and without binary interactions, we find that the inclusion of binary interactions makes the surface brightness greater (~0.1 mag arcsec 2) in FUV-band but smaller (~0.7 mag arcsec 2) in K-band, while it results in the FUV K color bluer (~0.8 mag). To reproduce the observations, a model that considers the binary interactions should make more gas fall onto the disk in the early time of the galaxy evolution, or increase the total stellar mass, or both.

关键词： M33 evolution binary stars

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Reanalysis of the Isotopic Mixture of Neutron-Capture Elements in the Metal-Poor Star HD 175305

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Chinese Physics Letters 2012年第1期29卷 299-302页

作者： ZHANG Jiang WANG Bo ZHANG Bo HAN Zhan-Wen National Astronomical Observatories/Yunnan Observatory Chinese Academy of SciencesKunming 650011 Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011 School of Mathematics and Science Shijiazhuang University of EconomicsShijiazhuang 050016 Department of Physics Hebei Normal UniversityShijiazhuang 050016

The neutron-capture process is traditionally postulated to be responsible for the nucleosynthesis of heavy elements beyond *** on theleast squares method and solar isotopic abundances from the classical model,we estimate the relative contributions of the s- and r-processes to the abundance of neutron-capture elements in the metalpoor star HD 175305 from the component *** the calculated component coefficients C_(r) and C_(s),the model predicts the isotopic fractions of elements Nd,Sm and Eu to be f_(142+144) =0.482,f_(152+154) =0.525 and f_(l51) =0.450,*** well as the observed abundances,the isotropic fractions are also consistent with the ***,for the first time,we estimated the contribution percentage of the two neutron processes (the r- and s-processes) from the observed isotopic fractions of different elements in HD 175305,*** r-process contribution of 67%^(+21%)_(-32%) from the 4604 (A) line of Sm.

关键词： elements Mixture analysis

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The surge-like eruption of a miniature filament

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Research in Astronomy and Astrophysics 2012年第3期12卷 300-312页

作者： Jia-Yan Yang Yun-Chun Jiang Dan Yang Yi Bi Bo Yang Rui-Sheng Zheng Jun-Chao Hong National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China Key Lab-oratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

We report on the rare eruption of a miniature Hα filament that took the form of a surge. The filament first underwent a full development within 46 min and then began to erupt 9 min later, followed by a compact, impulsive X-ray class M2.2 flare with a two-ribbon nature only at the early eruption phase. During the eruption, its top rose, whereas the two legs remained rooted in the chromosphere and showed little swelling perpendicular to the rising direction. This led to a surge-like eruption with a narrow angular extent. Similar to the recent observations for standard and blowout X- ray jets by Moore et al., we thus define it as a ＂blowout Hα surge.＂ Furthermore, our observations showed that the eruption was associated with （1） a coronal mass ejection guided by a pre-existing streamer, （2） abrupt, significant, and persistent changes in the photospheric magnetic field around the filament, and （3） a sudden disappearance of a small pore. These observations thus provide evidence that a blowout surge is a small- scale version of a large-scale filament eruption in many aspects. Our observations further suggest that at least part of the Hα surges belong to blowout-type cases, and the exact distinction between the standard and blowout Hα surges is important in understanding their different origins and associated eruptive phenomena.

关键词： Sun： activity—Sun： filaments—Sun： flares—Sun： magnetic field—Sun： coronal mass ejections （CMEs）

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Binary interactions and SFR calibrations

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Proceedings of the International Astronomical Union 2013年第S292期8卷 340-340页

作者： Fenghui Zhang Lifang Li Zhanwen Han National Astronomical Observatories/Yunnan Observatory CAS Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming China email: zhangfh@***

We discuss the effect of binary interactions on the tracers of star formation rate (including L1500, L2800, LHα, L[OII] and LFIR) at different metallicities (0.0001–0.03).

关键词： binaries: general — galaxies: fundamental parameters — galaxies: general

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The connection between radio and γ-ray emission in Fermi/LAT blazars

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Research in Astronomy and Astrophysics 2012年第11期12卷 1475-1485页

作者： Xu-Liang Fan Jin-Ming Bai Hong-Tao Liu Liang Chen Neng-Hui Liao National Astronomical Observatories / Yunnan Observatory Chinese Academy of SciencesKunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy ofSciences Kunming 650011 China Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical ObservatoriesChinese Academy of Sciences Shanghai 200030 China Graduate University of Chinese Acaciemy of Sciences Beijing 100049 China

We collect the second Large Area Telescope AGN catalog （2LAC） and Monitor of Jets in AGN with VLBA Equipment （MOJAVE） quasi-simultaneous data to investigate the radio-γ connection of blazars. The cross sample contains 166 sources. The statistical analysis based on this sample confirms positive correlations between these two bands, but the correlations become weaker as the γ-ray energy increases. The statistical results between various parameters show negative correla- tions of γ-ray photon spectral index with γ-ray loudness for both Flat Spectrum Radio Quasars （FSRQs） and BL Lacertae objects, positive correlations of γ-ray variability index with the γ-ray loudness for FSRQs, a negative correlation of the γ-ray variabil- ity index with the γ-ray photon spectral index for FSRQs, and negative correlations of γ-ray photon spectral index with γ-ray luminosity for FSRQs. These results suggest that the γ-ray variability may be due to changes inside the γ-ray emission region like the injected power, rather than changes in the photon density of the external radiation fields, and the variability amplitude tends to be larger as the γ-rays are closer to the high energy peak of the spectral energy distribution （SED）. No correlation of variabil- ity index found for BL Lacertae objects implies that variability behavior may differ below and above the peak energy.

关键词： BL Lacertae objects general -- galaxies： jets -- quasars general -- radio continuum galaxies -- gamma rays observations

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A POSSIBLE EXPLANATION OF ENERGY DEPENDENCE OF GRB PULSE WIDTH

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International Journal of Modern Physics: Conference Series 2013年第23期ijmpcs卷 301-303页

作者： XIAO-HONG ZHAO ZHAO-YANG PENG National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences P. O. Box 110 Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Bodies Chinese Academy of Sciences P.O. Box 110 650011 Kunming China Department of Physics Yunnan Normal University Kunming 650092 China

Previous studies have found that the width of gamma-ray burst (GRB) pulse is energy dependent 1-2 and its origin keeps unknown. Here we find combining the curvature effect and the intrinsic Band spectrum could naturally result in the energy dependence of GRB pulse width. Our result suggests that the GRB decay phase is indeed related to the so-called curvature effect. A natural expectation of our study is for bursts with single power law, not Band spectrum, pulse width will not be energy dependent in our consideration.

关键词： Gamma rays bursts

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Note on the normalization of predicted gamma-ray burst neutrino flux

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Physical Review D 2012年第2期85卷 027301-027301页

作者： Zhuo Li Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China

We note that the theoretical prediction of neutrinos from gamma-ray bursts (GRBs) by IceCube overestimates the GRB neutrino flux, because they ignore both the energy dependence of the fraction of proton energy transferred to charged pions and the radiative energy loss of secondary pions and muons when calculating the normalization of the neutrino flux. After correction, GRB neutrino flux is reduced by a factor ∼5 for typical GRB spectral parameters and may be consistent with the present zero event detected by IceCube. More observations are important to push the sensitivity below the prediction and test whether GRBs are the sources of ultrahigh energy cosmic rays.

关键词： GAMMA ray bursts PROTONS NUCLEAR energy ASTRONOMICAL observations NEUTRINOS COSMIC rays NUCLEAR physics

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The principle of measuring unusual change of underground mass by optical astrometric instrument

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Geodesy and Geodynamics 2012年第4期3卷 32-38页

作者： Wang Jiancheng Chen Linfei Yang Lei Cheng Xiangming Su Jie Li Binghua Mao Wei Tie Qiongxian Yunnan Observatory/National Astronomical Observatories Key Laboratory for the Structure and Evolution of Celestial ObjectsChinese Academy of Sciences Kunming University of Science and Technology

Optical observations from a ground-based astrometric instrument provide a unique set of data sensi- tive to variations of local plumb line, which represent the change of local gravitational field on the ground. The local gravitational change could be caused by density variation or movement of underground mass in addition to tidal action. Earthquake was found to be related with gravitational change. A seismic zone could have abnor- mal underground material density, causing the variation of plume line on the ground. In this frame, the astro- metric telescope can measure the variation of local plumb line by observing the local astronomical longitudes and latitudes from stars in the Hipparcos catalog. In this study, we estimate the deflection angle of the plumb line on a ground site, and give a relation be- tween the angle, abnormal mass and site distance （depth and horizontal distance）. Then we derive the abnor- mality of underground material density using the plumb lines measured at different sites, and study the earth- quake gestation, development and occurrence. Using the deflection angles of plumb lines observed at two sites, we give a method to calculate the mass and the center of gravity of underground materials. We also esti- mate the abnormal masses of latent seismic zones with different energy, using thermodynamic relations, and in- troduce a new optical astrometric instrument we had developed.

关键词： astrometry earthquake forecast gravity instrument plumb line

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Bayesian analysis of galaxy spectral energy distributions with BayeSED

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Proceedings of the International Astronomical Union 2013年第S295期8卷 312-312页

作者： Yunkun Han Zhanwen Han National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences 100012 Beijing China email: hanyk@*** Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 650011 Kunming China email: zhanwenhan@***

In Han & Han (2012), we have preliminarily built BayeSED and applied it to a sample of hyperluminous infrared galaxies. The physically reasonable results obtained from Bayesian model comparison and parameter estimation show that BayeSED could be a useful tool for understanding the nature of complex systems, such as dust obscured starburst-AGN composite galaxies, from decoding their complex SEDs. In this contribution, we present a more rigorous test of BayeSED by making a mock catalog from model SEDs with the value of all parameters to be known in advance.

关键词： galaxies: active galaxies: ISM methods: data analysis methods: statistical

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Photometric analysis of a blue straggler eclipsing binary in the old open cluster NGC 2141

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Science China(Physics,Mechanics & Astronomy) 2012年第8期55卷 1500-1504页

作者： LUO YangPing WANG Bo CHEN HaiLiang ZHANG XiaoBin HAN ZhanWen National Astronomical Observatories/Yunnan ObservatolT Chinese Academy of Sciences Kunming 650011 China Key blboratory.for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China Graduate University of Chinese Academy of Sciences Beijing 100049 China National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

To understand the formation mechanism of blue stragglers in open clusters, we conducted a photometric analysis for a blue straggler eclipsing binary in the old open cluster NGC 2141. By using the least square fitting of times of minima, we derived the ephemeris and redetermined the orbital period of this system to be 0.6227 d. We have also done a photometric analysis for light curve with the Wilson-Devinney Code （2003）. The photometric solutions reveal a semi-detached binary with the second- ary component filling its Roche lobe. The photometric mass ratio MJMI （secondary/primary） was determined to be 0.190_＋0.002 and the ratio of V-band luminosity L2/LI（V） is about 0.033_＋0.001, which indicates the secondary component is overluminous. Thus, this blue straggler likely results from a substantial mass exchange between these two components.

关键词： open cluster eclipsing binary blue straggler photometry

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