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Discrepancy between infrared and optical emission in some Be stars

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Chinese Science Bulletin 2002年第18期47卷 1511-1513页

作者： LIU Qingzhong & WEI JianyanPurple Mountain Observatory, Chinese academy of sciences, Nanjing2.0008, {2. national astronomical observatories, Chinese academy of sciences, Beijing 100012, {2. Purple Mountain Observatory Chinese Academy of Sciences Nanjing China national astronomical {2. Chinese Academy of Sciences Beijing China

An expanding ring model is put forward to investigate the original regions of Ha line emission and infrared excess emission in Be stars, by taking optical depth into account. We find that the two regions depend strongly on the physical properties of the envelope of Be stars such as the initial density and density structure. This model can be used to qualitatively interpret the disagreement between the near infrared excess and the equivalent width (EW) of Ha emission line, as observed in some Be stars.

关键词： Be star emission line near infrared excess.

The periodicity of 3. 2.3.s radio light curve at 15 GHz found by the wavelet method

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 252-255页

作者： ZHANG HaoJing1,2.ZHAO Gang1,ZHANG Xiong3.& BAI JinMing4 1 national astronomical {2.,Chinese academy of sciences,Beijing 100012.china 2.Graduate University of Chinese academy of sciences,Beijing 100049,china 3.Department of Physics,Yunnan Normal Univeristy,Kunming 650092.china 4 national astronomical {2./Yunnan Observatory,Chinese academy of sciences,Kunming 650011,china 1. national astronomical {2. Chinese Academy of Sciences Beijing 100012 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Department of Physics Yunnan Normal Univeristy Kunming 650092 China4. National Astronomical Observatories/ Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China

We analyze the radio light curve of 3. 2.3.at 15 GHz from 1963.to 2.06 taken from the database of the literature,and find evidence of quasi-periodic *** the wavelet analysis method to analyze these data,our results indicate that:(1) There is one main outburst period of P1=8.1±0.1 year in 3. *** period is in a good agreement with Ozernoi's analysis in optical bands.(2. Based on the possible periods,we expect the next burst in 2.14 October.

关键词： quasar object individual(3. 2.3. radio band’s periodicity analysis wavelet method

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

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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 {3. astronomical {2./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 {2./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

A Possible Origin of 6.7 GHz Linear Methanol Maser Sources

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Chinese Journal of Astronomy and Astrophysics 2001年第5期1卷 389-394页

作者： Ye Xu (Shanghai astronomical Observatory, Chinese academy of {2., Shanghai 2.003.) (Urumqi astronomical Observatory, Chinese academy of {2., Urumqi 83.011) (national astronomical observatories, Chinese academy of {2., Beijing 100012) E-mail Shanghai astronomical Observatory Chinese Academy of Sciences Shanghai 200030 []Urumqi Astronomical Observatory Chinese Academy of Sciences Urumqi 830011 []National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

We present a model which explains the observed multi-linear spatial structures with different velocity gradients of the 50-61A+ methanol line at 6.7 GHz. We consider this and other hypotheses and conclude that the met... 详细信息

关键词： masers - stars: circumstellar matter - stars: formation

Learning Vector Quantization for Classifying astronomical Objects

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Chinese Journal of Astronomy and Astrophysics 2003年第2期3卷 183-190页

作者： Yan-Xia Zhang and Yong-Heng Zhaonational astronomical {2., Chinese {3. of sciences, Beijing 100012 national astronomical {2. CAS NAOC Beijing 100012 China

The sizes of astronomical surveys in different wavebands are increasing rapidly. Therefore, automatic classification of objects is becoming ever more important. We explore the performance of learning vector quantization (LVQ) in classifying multi-wavelength data. Our analysis concentrates on separating active sources from non-active ones. Different classes of X-ray emitters populate distinct regions of a multidimensional parameter space. In order to explore the distribution of various objects in a multidimensional parameter space, we positionally cross-correlate the data of quasars, BL Lacs, active galaxies, stars and normal galaxies in the optical, X-ray and infrared bands. We then apply LVQ to classify them with the obtained data. Our results show that LVQ is an effective method for separating AGNs from stars and normal galaxies with multi-wavelength data.

关键词： method: data analysis - method: statistical - catalogs

Searching for Variable Stars in and around Open Clusters

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Chinese Journal of Astronomy and Astrophysics 2002年第6期2卷 481-486页

作者： Yu Xin, Xiao-Bin Zhang and Li-Cai Dengnational astronomical {2., Chinese {3. of sciences, Beijing 100012 national astronomical {2. Chinese Academy of Sciences Beijing 100012 China

We present a snapshot-of our recent results of a variable star survey in 1 degree fields around three open clusters: NGC 188, NGC 7789 and M67. A total number of 3. variable stars are newly discovered, including 2. W ... 详细信息

关键词： open clusters : individual : NGC 188, NGC 7789 and M67 stars : variables

The Hβ Chromospheric Magnetic Field in a Quiescent Filament

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Chinese Journal of Astronomy and Astrophysics 2003年第1期3卷 87-94,i002-i004页

作者： Xing-Ming Bao and Hong-Qi Zhangnational astronomical {2., Chinese {3. of sciences, Beijing 100012 baoxm@*** national astronomical {2. CAS NAOC Beijing 100012 China

We observed the line-of-sight magnetic field in the chromosphereand photosphere of a large quiescent filament on the solar disk on September 6, 2.01 using the Solar Magnetic Field Telescope in Huairou Solar Observing Station. The chromospheric and photospheric magnetograms together with Hβ filtergrams of the filament were examined. The filament was located on the neutral line of the large scale longitudinal magnetic field in the photosphere and the chromosphere. The lateral feet of the filament were found to be related to magnetic structures with opposite polarities. Two small lateral feet are linked to weak parasitic polarity. There is a negative magnetic structure in the photosphere under a break of the filament. At the location corresponding to the filament in the chromospheric magnetograms, the magnetic strength is found to be about 40-70 Gauss (measuring error about 3. Gauss). The magnetic signal indicates the amplitude and orientation of the internal magnetic field in the filament. We discuss several possible causes which may produce such a measured signal. A twisted magnetic configuration inside the filament is suggested .

关键词： Sun: chromosphere - Sun: filaments - Sun: magnetic fields

A comparative analysis on two solar proton events

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Chinese Science Bulletin 2007年第1期52卷 47-51页

作者： LE GuiMing1,2.3.4, HAN YanBen2.& ZHANG YiJun3.1 Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites, china Meteorological Administration, Beijing 100081, china 2.{2. astronomical observatories, Chinese academy of sciences, Beijing 100012, china 3.Chinese academy of Meteorological sciences, china Meteorological Administration, Beijing 100081, china 4 {2. Center for Space Weather, china Meteorological Administration, Beijing 100081, china Key Laboratory of Radiometric Calibration and Validation for EnvironmentalSatellites China Meteorological Administration Beijing 100081 China

This paper presents a comparative analysis on the two Solar Proton Events (SPE), which occurred on 14 July 2.00 (Bastille Day) and 2. October 2.03.(2.OCT03. respectively. It is found that although the peak flux of the latter seemed to be greater than that of the former based on geostationary observations, the maximum intensities of the energetic protons (>10 MeV and 3. MeV) during the Bastille Day event were all higher than those of the 2.OCT03.event according to the interplanetary observations. Further analysis indicated that the quantity of the seed particles, which could be accelerated to the energies exceeding 10 and 3. MeV by the Coronal Mass Ejection (CME)-driven shock on 14 July 2.00, was far larger than that of the 2.OCT03.event. In the Bastille Day case, when the CME approached to the height around 14 R⊙, the CME-driven shock would reach its maximum capacity in accelerating the solar en- ergetic protons (>100 MeV). In contrast, on 2. October 2.03. when CME approached to the height about 58R⊙, the CME-driven shock reached its highest potential in accelerating the solar energetic protons of the same category. At this moment, the peak flux (>100 MeV) was about 155 pfu, which was much lower than 3.5 pfu measured on 14 July 2.00. This demonstrated that in the Bastille Day event, the quantity of the seed particles, which could be accelerated to the energy beyond 100 MeV, was significantly larger than its counterpart in the 2.OCT03.case. Therefore, the peak flux of an SPE event depends not only on the interplanetary intensity of the solar energetic particles, but also on the velocity of the associated CME-driven shock, and the quantity of the seed particles as well as on the interplanetary magnetic en- vironment. This paper also reveals that the magnetic sheath associated with ICME on 2. October 2.03.captured a large number of solar energetic protons, including those having energy greater than 100 MeV.

关键词：太阳质子 CME 太阳耀斑太阳系

Verification of Short-Term Predictions of Solar Soft X-ray Bursts for the Maximum Phase (2.00-2.01) of Solar Cycle 2.

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Chinese Journal of Astronomy and Astrophysics 2003年第6期3卷 563-568页

作者： Cui-Lian Zhu and Jia-Long Wangnational astronomical {2., Chinese {3. of sciences, Beijing 100012 national astronomical {2. Chinese Academy of Sciences Beijing 100012

We present a verification of the short-term predictions of solar X-ray bursts for the maximum phase (2.00–2.01) of Solar Cycle 2., issued by two prediction centers. The results are that the rate of correct predictions is about equal for RWC-{3. and WWA; the rate of too high predictions is greater for RWC-{3. than for WWA, while the rate of too low predictions is smaller for RWC-{3. than for WWA.

关键词： sun: X-ray bursts sun: short-term prediction