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Gamma-ray Bursts: a Probe of Black Holes

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chinese Journal of Astronomy and Astrophysics 2001年第6期1卷 487-493页

作者： Wei Wang and Yong-Heng Zhao national astronomical observatories, chinese academy of sciences, beijing 100012 national astronomical observatories Chinese Academy of Sciences Beijing 100012

There is strong evidence for the existence of black holes (BHs) in some X-ray binaries and in most galactic nuclei based on different types of measurement, but black holes have not been definitely identified for the lack of very firm observational evidence up to now. Because direct evidence for BHs should come from determination of strong gravitational redshift, we expect an object can fall into the region near the BH horizon where radiation can be detected. Therefore the object must be a compact star such as a neutron star (NS), and intense astrophysical processes will release highly energetic radiation that is transient and fast-varying. These characteristics may point to the observed gamma-ray bursts (GRBs). Recent observations of iron lines suggest that afterglows of GRBs show properties similar to those observed in active galactic nuclei (AGNs), implying that the GRBs may originate from intense events related to black holes. A model for GRBs and after-glows is proposed here to obtain the range of gravitational redshifts (zg) of GRBs with known cosmological redshifts. Here, we provide a new method that, with a search for high-energy emission lines (X- or -γ-rays) in GRBs, one can determine the gravitational redshift. We expect zg to be 0.5 or even larger, so we can rule out the possibility of other compact objects such as NSs, and identify the central progenitors of GRBs as black holes.

关键词： black hole physics - accretion accretion disks - gamma rays: burst

“Small Equipment Strategy” in the Development of Astronomy

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chinese Journal of Astronomy and Astrophysics 2003年第1期3卷 1-11页

作者： Shou-Guan Wangnational astronomical observatories, chinese academy of sciences, beijing 100012 shouguanwang@*** national astronomical observatories CAS NAOC Beijing 100012 China

Astronomy is an observational science. This paper points out that in the development of astronomy, the means of observation at every stage has as its main body the large equipment of the time, but equally important is the simultaneous development of small equipment as strategic complement. A number of historical examples are cited. The recently suggested 'Special Radio Telescope Dedicated to Pulsar Research' originates in the small equipment strategy, and a brief introduction to this instrument is included here.

关键词： instrumentation telescopes

A Check on the Variations of Earth's Rotation with an Ancient Solar Eclipse

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chinese Journal of Astronomy and Astrophysics 2003年第6期3卷 569-575页

作者： Yan-Ben Han and Qi-Yuan Qiao national astronomical observatories, chinese academy of sciences, beijing 100012 national astronomical observatories Chinese Academy of Sciences Beijing 100012

We address the relation between an ancient total eclipse, which occurred on A.D.1542 August 11 and the variation of Earth's rotation. The total eclipse was recorded in some ancient chinese books, especially in local chronicles. Some of the documents include useful information for determining the location of the totality zone. The parameters of the eclipse are calculated by using the DE406 Ephemeris. A high-precision value of ΔT which expresses the variation of the Earth's rotation, of about 300 ~ 380 s, is obtained.

关键词： solar eclipse earth rotation

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

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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 astronomical observatories, chinese academy of sciences, beijing 100012 national astronomical observatories Chinese Academy of Sciences Beijing 100012

The Large Sky-Area Multi-Object Spectroscopic Telescope (LAMOST) under construction by the national astronomical observatories 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

Annual Modulation in Intraday Variability Timescales of Extragalactic Radio Sources

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chinese Journal of Astronomy and Astrophysics 2001年第2期1卷 133-143页

作者： Shan-Jie Qian and Xi-Zhen Zhang (beijing astronomical Observatory, national astronomical observatories, chinese academy of sciences, beijing 100012) beijing astronomical Observatory National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

Annual modulations in timescales of intraday variability (IDV hereafter) are discussed for six extragalactic sources: 0716+714, 0917+624, 0954+65, 1749+70, 1803+78 and 2007+77. The timescales calculated from scintillation theory are compared with the observational data . It is emphasized that systematic observations are required to identify the phenomenon and to determine the motion of the interstellar medium with respect to the Local Standard of Rest. In addition, significant deviations from the annual modulation could be due to intrinsic variations.

关键词： scattering - ISM: kinematics - BL Lacertae objects: individual: 0716+71 - quasars: individual: 0917+62 - radiation mechanisms: non-thermal

Discovery of an Optical Jet in the Rosette Nebula: Rosette HH2

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chinese Journal of Astronomy and Astrophysics 2003年第6期3卷 495-498页

作者： Jin-Zeng Linational astronomical observatories, chinese academy of sciences, beijing 100012 national astronomical observatories Chinese Academy of Sciences Beijing 100012

We report on the discovery of an optical jet - Rosette HH2 - in the RosetteNebula. The jet system bears unique features for residing at the center of a giant HII region, andits energy source is visible with apparently very low extinction along the line of sight. Unlikemost other Herbig-Haro jets, this jet indicates a high-excitation origin, and its extended portionshows a seemingly intact structure, instead of normally a shocked working surface, which isattributed to photoablation.

关键词： stars: formation stars: pre-main sequence herbig-haro objects ISM: jetsand outflows

Molecular Gas and Dust in the Massive Star Forming Region S 233 IR

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chinese Journal of Astronomy and Astrophysics 2004年第5期4卷 440-454页

作者： Rui-Qing Mao and Qin Zeng1 Purple Mountain Observatory, chinese academy of sciences, Nanjing 210008 2 national astronomical observatories, chinese academy of sciences, beijing 100012 Purple Mountain Observatory Chinese Academy of Sciences national astronomical observatories Chinese Academy of Sciences

The massive star forming region S 233 IR is observed in the molecular lines CO J = 2–1, 3–2, NH3 (1,1), (2,2) and the 870 um dust continuum. Four submillimeter continuum sources, labelled SMM 1–4, are revealed in the 870 um dust emission. The main core, SMM1, is found to be associated with a deeply embedded near infrared cluster in the northeast; while the weaker source SMM2 coincides with a more evolved cluster in the southwest. The best fit spectral energy distribution of SMM1 gives an emissivity of β = 1.6, and temperatures of 32 K and 92 K for the cold- and hot-dust components. An SMM1 core mass of 246 M☉, and a total mass of 445 M☉ are estimated from the 870 um dust continuum emission. SMM1 is found to have a temperature gradient decreasing from inside out, indicative of the presence of interior heating sources. The total outflow gas mass as traced by the CO J = 3–2 emission is estimated to be 35 M☉. Low velocity outflows are also found in the NH3 (1,1) emission. The non-thermal dominant NH3 line width as well as the substantial core mass suggest that the SMM1 core is a ``turbulent, massive dense core', in the process of forming a group or a cluster of stars. The much higher star formation efficiency found in the southwest cluster supports the suggestion that this cluster is more evolved than the northeast one. Large near infrared photometric variations found in the source PCS-IR93, a previously found highly polarized nebulosity, indicate an underlying star showing the FU Orionis type of behavior.

关键词： ISM: jets and outflows ISM: molecules ISM: dust, extinction stars:formation ISM: individual

Detectability of rotation-powered pulsars in future hard X-ray surveys

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Research in Astronomy and Astrophysics 2009年第11期9卷 1241-1258页

作者： Wei Wang national astronomical observatories Chinese Academy of Sciences Beijing 100012 China

Recent INTEGRAL/IBIS hard X-ray surveys have detected about 10 young pulsars. We show hard X-ray properties of these 10 young pulsars, which have a luminosity of 10^33 - 10^37 erg s^-1 and a photon index of 1.6-2.1 in the energy range of 20-100 keV. The correlation between X-ray luminosity and spin-down power of Lx ∝ Lsd^1.31 suggests that the hard X-ray emission in rotation-powered pulsars is dominated by the pulsar wind nebula （PWN） component. Assuming spectral properties are similar in 20-100keV and 2-10 keV for both the pulsar and PWN components, the hard X-ray luminosity and flux of 39 known young X-ray pulsars and 8 millisecond pulsars are obtained, and a correlation of Lx ∝ Lsd^1.5 is derived. About 20 known young X-ray pulsars and 1 millisecond pulsars could be detected with future INTEGRAL and HXMT surveys. We also carry out Monte Carlo simulations of hard X-ray pulsars in the Galaxy and the Gould Belt, assuming values for the pulsar birth rate, initial position, proper motion velocity, period, and magnetic field distribution and evolution based on observational statistics and the Lx - Lsd reltions：Lx ∝Lsd^1.31 and Lx∝Lsd^1.5 More than 40 young pulsars （mostly in the Galactic plane） could be detected after ten years of INTEGRAL surveys and the launch of HXMT. So, the young pulsars would be a significant part of the hard X-ray source population in the sky, and will contribute to unidentified hard X-ray sources in present and future hard X-ray surveys by INTEGRAL and HXMT.

关键词： pulsars general -- stars neutron -- X-rays stars -- radiation mechanisms nontherrnal

IRAS 01005+7910:a High Galactic Latitude Post-AGB Star

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chinese Journal of Astronomy and Astrophysics 2002年第3期2卷 193-196页

作者： Jing-Yao Hunational astronomical observatories, chinese academy of sciences, beijing 100012 national astronomical observatories Chinese Academy of Sciences Beijing 100012

IRAS 01005+7910 is a cold IRAS source. We present its optical identification, photometric and spectroscopic observation results. Its optical counterpart is classified as a B2Ie star with V magnitude 10.85. Its Hα line shows the P Cygni profile. According to its location in the Galaxy (b = 16.6), we consider it to be a post-AGB star or a proto-planetary nebula.

关键词： stars: post-AGB - infrared: stars - stars: evolution