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An orbital period investigation of the Algol-type eclipsing binary VW Hydrae

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chinese Journal of Astronomy and Astrophysics 2009年第3期9卷 307-314页

作者： Jia Zhang Sheng-Bang Qian Boonrucksar Soonthomthum national astronomical {2./yunnan observatory Chinese Academy of Sciences Kunming 650011 China Graduate School of the chinese Academy of sciences Beijing 100039 China national astronomical Research Institute of Thailand/Ministry of Science and Technology Bangkok Thailand

Orbital period variations of the Algol-type eclipsing binary, VW Hydrae, are analyzed based on one newly determined eclipse time and the other times of light minima collected from the literature. It is discovered that the orbital period shows a continuous increase at a rate ofdP/dt = ＋6.34 × 10^-7 d yr^-1 while it undergoes a cyclic change with an amplitude of 0.0639 d and a period of 51.5 yr. After the long-term period increase and the large-amplitude period oscillation were subtracted from the O-C curve, the residuals of the photoelectric and CCD data indicate a small-amplitude cyclic variation with a period of 8.75 yr and a small amplitude of 0.0048 d. The continuous period increase indicates a conservative mass transfer at a rate of dM2.dt = 7.89 × 10^-8 M⊙ yr^-1 from the secondary to the primary. The period increase may be caused by a combination of the mass transfer from the secondary to the primary and the angular momentum transfer from the binary system to the circumbinary disk. The two cyclic period oscillations can be explained by light-travel time effects via the presence of additional bodies. The small-amplitude periodic change indicates the existence of a less massive component with mass M3 〉 0.53 M⊙, while the large-amplitude one is caused by the presence of a more massive component with mass M4 〉 2.84M⊙. The ultraviolet source in the system reported by Kviz ＆ Rufener （1987） may be one of the additional components, and it is possible that the more massive one may be an unseen neutron star or black hole. The rapid period increase and the possibility of the presence of two additional components in the binary make it a very interesting system to study. New photometric and high-resolution spectroscopic observations and a detailed investigation of those data are required in the future.

关键词： stars binaries close - stars binaries eclipsing - multiple stars - stars individual (VW Hya)

The X-ray emission from the knots in 3C 12.

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 212-215页

作者： ZHANG Jin1,2.3 & li ShaoKun1,3 1 national {2. observatories/yunnan observatory,chinese Academy of sciences,kunming 650011,china 2.College of Physics and Electronic Engineering,Guangxi Teachers Education University,Nanning 53002.,china 3 Graduate University of the chinese Academy of sciences,Beijing 100049,china 1. national astronomical {2./yunnan observatory Chinese Academy of Sciences Kunming 650011 China 2. College of Physics and Electronic Engineering Guangxi Teachers Education University Nanning 530023 China 3. Graduate University of the chinese Academy of sciences Beijing 100049 China

3C 12. is a Seyfert galaxy with a well detected X-ray *** investigate the X-ray emission of its five jet knots and fit their spectral energy distributions(SEDs) from the radio to the X-ray bands with a single-zone lepton *** find that the SEDs of knots k7,s2.and s3 can be explained by synchrotron radiation,and the X-rays are the simple extension of the radio-optical emission component,but that of the inner knot k4 requires the IC/CMB model,in which the X-rays are due to the inverse Compton scattering of the cosmic microwave background photons by relativistic electrons in the jet with a beaming factor δ-*** outer knot k2. is resolved into a three-part *** is shown that the fitting of the X-rays from this knot with the IC/CMB model needs an extraordinary beaming factor δ-15-2. for a jet at the kpc *** the X-rays of knot k2. are produced by synchrotron radiation similar to k7,s2.and s3,they may be contributed by a relativistic electron population whose radiations in other wavelengths are not detected.

关键词： 3C 12. knots X-rays non-thermal emission

Spectroscopic study of globular clusters in the halo of M31 with the Xinglong 2.16 m telescope

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Research in Astronomy and Astrophysics 2011年第11期11卷 1298-1310页

作者： Zhou Fan1,2.Ya-Fang Huang1,2.Jin-Zeng li1,2.Xu Zhou1,2.jun Ma1,2.Hong Wu1,2.Tian-Meng Zhang1,2.and Yong-Heng Zhao1,{2. national astronomical observatories,chinese Academy of sciences,Beijing 100012.china 2.key Laboratory of Optical Astronomy,national astronomical observatories,chinese Academy of sciences,Beijing 100012.china national astronomical {2. Chinese Academy of Sciences Beijing 100012 China key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

We present spectroscopic observations for 11 confirmed globular clusters(GCs) of M31 with the OMR spectrograph on the 2.16 m telescope at the Xinglong site of national {2. observatories,chinese Academy of *** of our sample clusters are located in the halo of M31 and the most remote one is out to a projected radius of 78.75 kpc from the galactic *** all our sample clusters,we measured the lick absorption-line indices and radial *** is noted that most GCs in our sample are distinct from the HI rotation curve of galaxy M31,especially for B514,MCGC5,H12.and B517,suggesting that most of our sample clusters do not have a kinematic association with the star-forming young disk of the *** separately fitted the absorption line indices from the updated stellar population model of Thomas et *** two different tracks of Cassisi and Padova,by applying the χ2.minimization *** fitting results show that all our sample clusters are older than 10 Gyr,and metal-poor(2.38 ≤ [Fe/H] ≤ 0.91 dex).After merging the spectroscopic metallicity of our work with the previously published ones,we extended the cluster sample out to a projected radius of 117 kpc from the galaxy's *** found the metallicity gradient exists for all the confirmed clusters with a slope of 0.02. ± 0.001 dex kpc ***,the slope turns out to be 0.018 ± 0.001 dex kpc 1 for all the halo clusters,which is much *** we only consider the outer halo clusters with rp > 2. kpc,the slope becomes 0.010 ± 0.002.dex kpc 1 and if one cluster G001 is excluded from the outer halo sample,the slope is 0.004 ± 0.002.dex kpc ***,we conclude that the metallicity gradient for M31's outer halo clusters is not significant,which agrees well with previous findings.

关键词： galaxies individual(M31) — galaxies star clusters — globular clusters general — star clusters general

Steps Towards a Fully Automated Classification and Redshiftmeasurement Pipeline for LAMOST Spectra. I. Continuum level and wavelength estimation for galaxies

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同方期刊数据库

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chinese Journal of Astronomy and Astrophysics 2001年第6期1卷 563-572页

作者： A-li Luo and Yong-Heng Zhao national {2. observatories, chinese Academy of sciences, Beijing 100012 national astronomical {2. Chinese Academy of Sciences Beijing 100012

The Large Sky-Area Multi-Object Spectroscopic Telescope (LAMOST) under construction by the national astronomical {2. will yield up to four thousand multi-fiber spectra of stars and galaxies per field. The present series of papers describes the automated data-reduction pipeline currently being designed in order to cope with the anticipated flood of spectrographic data. In this preliminary paper, we present an automated method for estimating the continuum level, the positions of strong lines and the 4000 A break in galaxy spectra. In order to obtain detailed information on the continuum, we use a wavelet filter bank. After continuum fitting, our software searches for a 4000 A break and distinguishes between emission-line galaxies (ELGs) and non-ELGs according to whether the break is small or large. It then searches for strong lines and measures the intensities of emission lines and the equivalent widths of absorption lines. For non-ELGs, the absorption lines are identified automatically yielding redshift measurements.

关键词： methods: data analysis - techniques: spectroscopic - galaxies: emission lines - galaxies: absorption lines

The Coudé Echelle Spectrograph for the Xinglong 2.16m Telescope

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chinese Journal of Astronomy and Astrophysics 2001年第6期1卷 555-562页

作者： Gang Zhao and Hong-Bin li national {2. observatories, chinese Academy of sciences, Beijing 100012 national astronomical {2. Chinese Academy of Sciences Beijing 100012

A brief description of the NAO coude echelle spectrograph mounted on the 2.16 m telescope at Xinglong station is given. This echelle spectrograph is located at the coudé focus with a prism cross disperser. The echelle image covers the spectral region from 330 to 1100 nm displayed in 80 spectral orders in one exposure through two light beams. With a slit height of 2.m, spectral orders are separated by 15 to 2. pixels in blue region and by 7 to 19 pixels in red region. Alternatively, two additional resolution modes corresponding to different focal length cameras with resolving power R 16000, 170 000 in the blue beam and R = 13000, 170 000 in the red beam could be provided by this spectrograph. The bias, dark, wavelength calibration, flat field and science exposure are described in details. The limiting magnitude for 1 hour exposure with an S/N ratio of 100 scales to V = 9.5 in the red path and to V = 7.2.in the blue path.

关键词： instrumentation: spectrographs methods: observational - techniques: spectroscopic

Observational Accuracy of Sunrise and Sunset Times in the Sixth Century china

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chinese Journal of Astronomy and Astrophysics 2006年第5期6卷 629-634页

作者： Yong li national astronomical {2. Chinese Academy of Sciences Beijing 100012

The Daye Calendar was compiled in AD 597 in the Sui Dynasty. We investigate the records of sunrise and sunset times on the 2. solar-term days in the calendar. By converting the ancient chinese time units, Chen, ke and Fen to hour, minute and second, and carrying out a comparison between the ancient records and values computed with modem {2. theory, we find that the accuracy of solar measurements in the Sui period is remarkably high： for sunrise times, the average absolute deviation is 3.63 min （this value can be further reduced to 3.03 min when erroneous data are excluded）, and for sunset times it is 3.48 min. We also find that the observed sunrise and sunset times are strictly symmetrically distributed with respect to both the Winter Solstice and the Summer Solstice, with their deviations showing a similar symmetrical distribution as well. We give a discussion on the date of observation, the feature of the data, and possible reasons of the deviation.

关键词： history of astronomy -- astrometry -- solar-terrestrial relations -- methods statistical

Pulsars in FIRST Observations

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chinese Journal of Astronomy and Astrophysics 2002年第2期2卷 146-150页

作者： Xiang-Hua li and Jin-lin Han {2. astronomical observatories, chinese Academy of sciences, Beijing 100012 national astronomical {2. Chinese Academy of Sciences Beijing 100012

We identify 16 pulsars from the Survey of Faint Images of the Radio Sky at Twenty-cm (FIRST) at 1.4 GHz. Their positions and total flux densities are extracted from the FIRST catalog. By comparing the source positions with those in the PSR catalog, we obtain better determined positions of PSR J102.0}001, J1518+4904, J1652.2.51, and proper motion upper limits of PSR J0751+1807, J1012.5307, and J1640+2.2.. The proper motions of the other ten pulsars are consistent with the catalog values.

关键词： pulsar: general -stars: neutron

Model of Spectral Fluxes for Solar Spectrograph

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天文研究与技术 1999年第S1期 401-405页

作者： Cao Wenda, Song Qian (yunnan observatory, The {2. Academy of sciences, kunming 650011, china) (national astronomical observatories, The {2. Academy of sciences, Beijing 100012. china)

Taking use of the solar spectrograph in yunnan observatory, we built a model to estimate the spectral fluxes of solar spectrograph with computer and confirmed the result by observations. The spectral fluxes in visible... 详细信息

关键词： Model of Spectral Fluxes for Solar Spectrograph

Some Characteristic Parameters of the Basic Components of the Solar Radio Emission

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天文研究与技术 1999年第S1期 457-460页

作者： Ji Shuchen (Beijing astronomical observatory, The {2. Academy of sciences, Beijing 100080, china) (yunnan observatory, The {2. Academy of sciences, kunming 650011, china) (national astronomical observatories, The {2. Academy of sciences) $$

Four basic components of the solar radio emission: the quiet sun, the slowly varying component (SVC), the radio burst and the ultra-fast varying component (UFVC) are studied. As their six characteristic parameters: radiation source, brightness temperature, radiation lifetime, polarized radiation, radiation mechanism, and character of superposition are affirmed.

关键词： Radio Some Characteristic Parameters of the Basic Components Basic of the Solar Radio Emission