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Avoided crossings between non-radial modes in low mass RGB stars

Research in Astronomy and Astrophysics 2012年第12期12卷 1655-1665页

作者： Jun-Jun Guo1,2,3,Yan Li1,2 and Xiang-Jun Lai1,2 1 National Astronomical Observatories/Yunnan Observatory,Chinese Academy of Sciences, Kunming 650011,China 2 Key laboratory for the structure and evolution of celestial objects,Chinese Academy of Sciences,Kunming 650011,China 3 Graduate University of Chinese Academy of Sciences,Beijing 100049,China 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 Chinese Academy of Sciences Beijing 100049 China

Non-radial p modes and g modes appear simultaneously in red giant stars. Their frequencies have different variation rates,causing their frequencies to become close during stellar evolution so that avoided crossings *** separation between regions where acoustic waves and gravity waves propagate for l=1,2 and 3 is different,which results in the coupling efficiency also being *** present the results of numerical computations of the models we *** find that the two kinds of modes for l=2 and 3 need to be closer in frequency in order for a complete exchange to occur,compared to the case for modes with l=*** scaled oscillation frequencies also present better regularity with evolution than modes with l=1. In order to study the effect of the avoided crossings in detail,we set the mode which has the smallest mode inertia to be the p *** plot the two kinds of modes for l =1,2 and 3 in frequency and periodéchelle diagrams and find modes of l=2 and 3 fit the two relations better;they are more equally spaced in frequency and period than modes with l=*** careful observation of the two kinds oféchelle diagrams for l=2 and 3,we still find that some p modes shift a little from being equally spaced in frequency and some g modes,which are close to those p modes in period,shift a little from being equally spaced in ***,we study the relation between the deviation from period being equally spaced and the mode inertia of g modes for different *** g modes of l=1 with a period closer to the p mode have less inertia and the deviation is bigger in the periodéchelle *** deviation is also obvious. However g modes of l=2 and 3 shift a little or have almost no deviation from being equally spaced in period,even though some of them may have strong coupling and close mode inertia like in the p ***,we suggest a possible method for measuring period spacing of g modes precisely using mixed g modes with l=2 and 3 that have fewer observed mixed g m

关键词： stars：oscillations-stars：red giants

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Contact binaries:*** inspection of the HSB contact binary model by comparison of relationships obtained from theoretical light curves with that from astronomical observations

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Science China(Physics,Mechanics & Astronomy) 2012年第3期55卷 553-560页

作者： LUO ChangQing HUANG RunQian National Astronomical Observatories/Yunnan Observatory Chinese Academy of SciencesKunming 650011China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China Graduate University of Chinese Academy of Sciences Beijing 100049China

The light curve is one of the most important photometric characteristics of variable stars,which can supply physical information about many ***,light curves are the best candidate to inspect a theoretical model of *** important feature of the light curve is the difference of two light minima of the light curve,namely the difference between the primary eclipse depth and the secondary eclipse depth(DED).In this paper,the secondary eclipse depths of theoretical and observational light curves are ***,a method to calculate the theoretical light curves of an eclipsing binary with non-spherical components is proposed,which can be put into the HSB contact binary model [Huang R Q,et *** J Astron Astrophys,2007,7:235-244;Song H F,et *** J Astron Astrophys,2007,7:539-550].Theoretical light curves and the DED of the binary can be obtained at every evolutionary *** relationships of DED with mass and luminosity are presented and show special features for the contact ***,a large amount of observational data is collected,from which 11 massive,intermediate-mass contact binaries and 9 low-mass contact binaries are chosen and the two relationships are obtained using theoretical light ***,in order to check whether the HSB contact binary model can be used in contact binary systems with massive,intermediate-mass and low-mass components,a comparison is performed for the above mentioned relationships obtained from theoretical light curves with those from the astronomical *** results show a good agreement for contact binary systems with all different masses.

关键词： stars: binaries stars: evolution binaries: eclipsing

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Contact binaries:Ⅱ.The importance of deformation caused by rotation and tides to the light curve of a contact binary

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Science China(Physics,Mechanics & Astronomy) 2012年第5期55卷 899-906页

The theoretical light curves of contact binaries are calculated with and without putting in the contact binary evolution ***,we do not use the contact binary evolution model.A comparison of the light curve is performed with and without the deformation caused by rotation and *** shows that the light curve presents many differences,especially on the bottom and ***,we adopt the contact binary model [Huang R Q,et *** J Astron Astrophys,2007,7:235-244;Song H F,et *** J Astron Astrophys,2007,7:539-550] and compute the theoretical light curve with and without rotational and tidal effects by studying three binary systems(with low-,intermediate-and high-mass components).The bottom and top of the theoretical light curves are discussed and compared to *** results show that taking into account the rotational effect has a better agreement with observations than without ***,the deformation of the light curve of contact binaries caused by rotation and tides is very ***,the rotational and tidal effect can advance the start of the semi-detached,contact phase and the time of mass-reversal.

关键词： stars：inaries stars： evolution binaries： eclipsing

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Test of a low-mass contact binary model by comparing the relations obtained from theory with those from observations

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Science China(Physics,Mechanics & Astronomy) 2012年第4期55卷 706-716页

作者： SONG Fen HUANG RunQian Department of Astronomy Beijing Normal UniversityBeijing 100875China National Astronomical Observatories/Yunnan Observatory Chinese Academy of SciencesKunming 650011China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China

The W UMa-type contact binaries have been observed for several *** construct the evolutionary model for W UMa-type contact binaries,many difficulties were encountered due to the existence of complicated physical processes in such *** model introduced by Huang,Song and Bi includes some special and unique understandings of the physical processes of contact *** is necessary to test whether this model can be used for W UMa-type contact *** best way to test a theoretical model is to know whether this model can explain the observational phenomena of such *** this aim,a comparison is performed for the relations of mass-luminosity,mass-radius,and the distribution in the HR diagram obtained from the model introduced by Huang et *** those from the astronomical *** result of the comparison indicates that this model can be applied to W UMa-type contact binaries and can explain the observational phenomena of such binaries.

关键词： binaries： close stars： evolution stars： fundamental parameters stars： rotation

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Effects of binary interactions on the color evolution of M33

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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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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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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 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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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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