Nonlinear adaptive observer-based sliding mode control for LAMOST mount driving     

Wang-Ping Zhou  Yi Zheng  Wei Guo  Li Yu  Chang-Song Yang School of Information & Control Engineering  Nanjing University of Information Science & Technology  Nanjing  China  Nanjing Institute of Astronomical Optics & Technology  National Astronomical Observatories  Chinese Academy of Sciences  Nanjing 《中国天文和天体物理学报》2010,10(1)

Heavy disturbances caused mainly by wind and friction in the mount drive system greatly impair the pointing accuracy of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST).To overcome this negative effect,a third order Higher Order Sliding Mode (HOSM) controller is proposed.The key part of this approach is to design an appropriate observer which obtains the acceleration state.A nonlinear adaptive observer is proposed in which a novel polynomial model is applied to estimate the internal di...  相似文献   

A search for massive young stellar objects with 98 CH_3OH maser sources     

Tie Liu  Yue-Fang Wu  Ke Wang 《中国天文和天体物理学报》2010,10(1)

Using the 13.7m telescope of the Purple Mountain Observatory (PMO),a survey of the J = 1 - 0 lines of CO and its isotopes was carried out on 98 methanol maser sources in January 2008.Eighty-five sources have infrared counterparts within one arcmin.In the survey,except for 43 sources showing complex or multiple-peak profiles,almost all the 13CO line profiles of the other 55 sources have large line widths of 4.5km s-1 on average and are usually asymmetric.Fifty corresponding Infrared Astronomical Satellite (I...  相似文献   

Multifrequency emission analysis of TeV blazars H 2356–309 and 1ES 1218+304     

Yun-Yong Tang  Zu-Cheng Dai  Li Zhang 《中国天文和天体物理学报》2010,(5)

The multiband nonthermal emissions in radio, X-ray, and very high-energy(VHE) γ-ray bands from two distant blazars, H 2356–309 and 1ES 1218+304, havebeen detected, and, especially from recent observations with the Suzaku, MAGICand VERITAS telescopes, clearly reveal nonthermal power-law spectra. We study thebroadband nonthermal spectra of the two sources by using a combination of a one-zone homogeneous synchrotron self-Compton (SSC) model and an inhomogeneousconical jet model, where the new external backgrou...  相似文献   

New background quasars in the vicinity of the Andromeda Galaxy discovered with the Guoshoujing Telescope (LAMOST)     

Ruben García-Benito 《中国天文和天体物理学报》2010,10(7)

Planetary nebulae (PNe) are good tracers of the stellar populations, chem-ical composition and dynamics of their host galaxies. This paper reports the dis-covery of new PNe in the outskirts of the Andromeda Galaxy (M 31) with the Guoshoujing Telescope (GSJT, formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope-LAMOST) during its early commissioning phase. In total, 36 candidates selected from SDSS photometry are confirmed in terms of their PN nature, including 17 new discoveries and another 19 previously known emission line objects. Their positions, spectra, radial velocities and m5007 magnitudes are presented.We discuss the potential for detecting more PNe in M 31 with GSJT's multi-object spectroscopy and the related applications in studies of the dynamics and chemistry of M31 and its assemblage history.  相似文献   

Stellar mass estimation based on IRAC photometry for Spitzer SWIRE-field galaxies     

Yi-Nan Zhu      Hong Wu  Hai-Ning Li  Chen Cao National Astronomical Observatories  Chinese Academy of Sciences  Beijing  China  of Sciences  China Graduate University of Chinese Academy of Sciences  Beijing  China Institute of Space Science  Physics  Sh  ong University at Weihai  Sh  ong 《中国天文和天体物理学报》2010,10(4)

We analyze the feasibility of estimating the stellar mass of galaxies by mid-infrared luminosities based on a large sample of galaxies cross-identified from Spitzer SWIRE fields and the SDSS spectrographic survey.We derived the formulae to calculate the stellar mass by using IRAC 3.6 μm and 4.5 μm luminosities.The massto-luminosity ratios of IRAC 3.6 μm and 4.5 μm luminosities are more sensitive to the star formation history of galaxies than to other factors,such as the intrinsic extinction,metallicity and star formation rate.To remove the effect of star formation history,we used g-r color to recalibrate the formulae and obtain a better result.Researchers must be more careful when estimating the stellar mass of low metallicity galaxies using our formulae.Due to the emission from dust heated by the hottest young stars,luminous infrared galaxies present higher IRAC 4.5 μm luminosities compared to IRAC 3.6 μm luminosities.For most of type-Ⅱ AGNs,the nuclear activity cannot enhance 3.6 μm and 4.5 μm luminosities compared with normal galaxies.Star formation in our AGNhosting galaxies is also very weak,almost all of which are early-type galaxies.  相似文献   

Chandra archival study of (U)LIRGs with a double nucleus:binary AGNs?     

Jing-Bo Wang  Yu Gao Purple Mountain Observatory  Chinese Academy of Sciences  Nanjing  China  Graduate University of Chinese Academy of Sciences  Beijing 《中国天文和天体物理学报》2010,10(4)

We present our initial results from a study of 14(U)LIRGs with a doublenucleus(z <0.15)and an AGN signature in the Chandra archive.The goals of our study are to search for more possible cases of binary AGNs and to investigate the X-ray properties and energy sources of these energetic objects,a major effort devoted specifically to searching for binary AGNs from(U)LIRGs.Our studies suggest that Mrk 266 might be a new candidate in hosting binary AGNs supported by X-ray observations.Our analysis shows that most(U)LIRGs are essentially weak X-ray sources and are not dominated by AGNs,due to both the lack of Fe K line detections and weak emission in the hard X-ray band.We find evidence for thermal emission with temperature kT～0.7 keV in seven nuclear regions,and this component is possibly associated with the nuclear or circumnuclear starburst.The soft and hard X-ray to far-infrared ratios also suggest that most(U)LIRGs are not energetically dominated by AGNs.Therefore,this study only provides one additional candidate of binary AGNs.We cannot rule out the existence of low luminosity AGNs and thus binary AGNs in all of them,particulaxly,those highly obscured and spatially unresolved systems.Nine of 14(U)LIRGs,including three previously known binary AGNs and a new candidate Mrk 266,clearly have obvious X-ray counterparts to their double optical/near-IR nuclei,whereas only two out of 14 have one obvious X-ray counterpart detected.Additionally,Arp 220 and Mrk 273 are not spatially resolved owing to their small nuclear separations(～1"),and no significant X-ray detection in the most distant source.  相似文献   

Testing and data reduction of the Chinese Small Telescope Array(CSTAR)for Dome A,Antarctica     

Xu Zhou    Zhen-Yu Wu  Zhao-Ji Jiang  Xiang-Qun Cui  Long-Long Feng  Xue-Fei Gong  Jing-Yao Hu  Qi-Sheng Li  Gen-Rong Liu  Jun Ma  Jia-Li Wang  Li-Fan Wang  Jiang-Hua Wu  Li-Rong Xia  Jun Yan  Xiang-Yan Yuan  Feng-Xiang Zhai  Ru Zhang  Zhen-Xi Zhu  National Astronomical Observatories  Chinese Academy of Sciences  Beijing  China  Nanjing Institute of Astronomical Optics & Technology  National Astronomical Observatories  Nanjing  China Purple Mo... 《中国天文和天体物理学报》2010,10(3)

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Debris disks: seeing dust, thinking of planetesimals and planets     

Alexander V. Krivov 《中国天文和天体物理学报》2010,10(5)

Debris disks are optically thin, almost gas-free dusty disks observed arounda significant fraction of main-sequence stars older than about 10 Myr. Since the circumstellar dust is short-lived, the very existence of these disks is considered as evi-dence that dust-producing planetesimals are still present in mature systems, in whichplanets have formed – or failed to form – a long time ago. It is inferred that theseplanetesimals orbit their host stars at asteroid to Kuiper-belt distances and continuallysupply ...  相似文献   

Aggregate dust model to study the polarization properties of comet C/1996 B2 Hyakutake     

Himadri Sekhar Das  Abinash Suklabaidya  Saonli Datta Majumder  Asoke Kumar Sen 《中国天文和天体物理学报》2010,10(4)

The observed linear polarization data of comet Hyakutake are studied at wavelengths λ=0.365 μm,λ=0.485 μm and 0.684 μm through simulations using Ballistic Particle-Cluster Aggregate and Ballistic Cluster-Cluster Aggregate aggregates of 128 spherical monomers.We first found that the size parameter of the monomer,x～1.56-1.70,turned out to be the most suitable which provides the best fits to the observed dust scattering properties at three wavelengths:λ=0.365 μm,0.485 μm and 0.684 μm.Thus,the effective radius of the aggregate(r)lies in the range 0.45 μm ≤ r≤ 0.49 μm at λ=0.365 μm;0.60μm < r < 0.66 μm at λ=0.485 μmand 0.88 μm < r < 0.94 μm at λ=0.684 μm.Now using superposition T-MATRIX code and the power-law size distribution,n(r)～r-3,the best-fitting values of complex refractive indices are calculated for the observed polarization data at the above three wavelengths.The best-fitting complex refractive indices(n,k)are found to be (1.745,0.095)at λ=0.365 μm,(1.743,0.100)at λ=0.485 μm and(1.695,0.100)at λ=0.684 μm.The refractive indices derived from the present analysis correspond to a mixture of both silicates and organics,which are in good agreement with the in situ measurement of comets by different spacecraft.  相似文献   

Several fourth-order force gradient symplectic algorithms     

Jia Xu  Xin Wu 《中国天文和天体物理学报》2010,10(2)

By adding force gradient operators to symmetric compositions, we build a set of explicit fourth-order force gradient symplectic algorithms, including those of Chin and coworkers, for a separable Hamiltonian system with quadratic kinetic energy T and potential energy V . They are extended to solve a gravitational n-body Hamiltonian system that can be split into a Keplerian part H 0 and a perturbation part H 1 in Jacobi coordinates. It is found that the accuracy of each gradient scheme is greatly superior to ...  相似文献