polarimetric and photometric observations of split comet C/2001 A2 (LINEAR)     

Rosenbush  Vera  Kiselev  Nikolai  Velichko  Sergey 《Earth, Moon, and Planets》2002,90(1-4):423-433

We present the results of polarimetric and photometricobservations of split Comet C/2001 A2 (LINEAR), which wereobtained at the 70-cm telescope of the Astronomical Observatoryof Kharkiv National University between 30 June and 31 July 2001.The brightest fragment of the comet, nucleus B, was observed.Eight narrowband cometary filters in the continuum and in emissionbands and a wideband red filter have been used. The comet wasobserved through apertures of 88, 33, and 19 arcsec. Polarizationphase curves were obtained for the continuum and for the firsttime, for NH₂(0, 7, 0) emission. The degree of polarization ofthe light scattered by the dust decreases with the increase ofaperture size. An important temporal variation of the polarizationwith a rotation of the polarization plane was observed at twophase angles (26.5° and 36.2°). Molecular column densities and production rates of CN, C₂,C₃, and NH₂ species are calculated in the framework of theHaser model. A comparative analysis of the temporal variations ofthe visual magnitudes, gas and dust production rates, dust colorand polarization are presented.  相似文献   

Deep inside the core of Abell 1795: the Chandra view   总被引：1，自引：0，他引：1  

S.Ettori  A. C.Fabian  S. W.Allen  R. M.Johnstone 《Monthly notices of the Royal Astronomical Society》2002,331(3):635-648

We present X-ray spatial and spectral analysis of the Chandra data from the central     of the cluster of galaxies Abell 1795. The plasma temperature rises outwards by a factor of 3, whereas the iron abundance decreases by a factor of 4. The spatial distribution of oxygen, neon, sulphur, silicon and iron shows that supernovae Type Ia dominate the metal enrichment process of the cluster plasma within the inner 150 kpc. Resolving both the gas density and temperature in nine radial bins, we recover the gravitational mass density profile and show that it flattens within 100 kpc as   ρ _DM∝ r ^-0.6  with a power-law index flatter than −1 at >3 σ level. The observed motion of the central galaxy and the presence of excesses and deficits along the north–south direction in the brightness distribution indicate that the central cluster region is not relaxed. In the absence of any non-gravitational heating source, the data from the inner ∼200 kpc indicate the presence of a cooling flow with an integrated mass deposition rate of about 100 M_⊙ yr⁻¹. Over the same cluster region, the observed rate of 74 M_⊙ yr⁻¹ is consistent with the recent XMM-Newton Reflection Grating Spectrometer limit of 150 M_⊙ yr⁻¹.  相似文献   

Excitation of solar-like oscillations: From PMS to MS stellar models     

R. Samadi  M. -J. Goupil  E. Alecian  F. Baudin  D. Georgobiani  R. Trampedach  R. Stein  å. Nordlund 《Journal of Astrophysics and Astronomy》2005,26(2-3):171-184

The amplitude of solar-like oscillations results from a balance between excitation and damping. As in the sun, the excitation is attributed to turbulent motions that stochastically excite thep modes in the uppermost part of the convective zone. We present here a model for the excitation mechanism. Comparisons between modeled amplitudes and helio and stellar seismic constraints are presented and the discrepancies discussed. Finally the possibility and the interest of detecting such stochastically excited modes in pre-main sequence stars are also discussed.  相似文献   

十六位模数转换器AD7705及其应用   总被引：12，自引：0，他引：12  

敖振浪  李源鸿  谭鉴荣 《成都信息工程学院学报》2003,18(3):281-286

AD7705是AD公司最近推出的十六位模数转换器。我们主要介绍了它的功能和特点，给出了基于AD7705实际应用的硬件、软件设计方法，以及部分程序源代码，总结了实际应用中必须注意的几个技术问题。  相似文献   

Ram pressure stripping and the formation of cold fronts     

S. Heinz  E. Churazov  W. Forman  C. Jones  U. G. Briel 《Monthly notices of the Royal Astronomical Society》2003,346(1):13-17

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Optical spectroscopy of flares from the black hole X-ray transient A0620–00 in quiescence     

T. Shahbaz  R. I. Hynes  P. A. Charles  C. Zurita  J. Casares  C. A. Haswell  S. Araujo-Betancor  C. Powell 《Monthly notices of the Royal Astronomical Society》2004,354(1):31-42

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BeppoSAX temperature maps of galaxy clusters in the Corona Borealis supercluster: A2061, A2067 and A2124     

F. Marini  S. Bardelli  E. Zucca  S. De Grandi  A. Cappi  S. Ettori  L. Moscardini  G. Tormen  A. Diaferio 《Monthly notices of the Royal Astronomical Society》2004,353(4):1219-1230

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A new white dwarf constraint on the rate of change of the gravitational constant     

Marek Biesiada  Beata Malec 《Monthly notices of the Royal Astronomical Society》2004,350(2):644-648

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Globular clusters as probes of galaxy evolution: NGC 5128     

S. K. Yi  E. Peng  H. Ford  S. Kaviraj  S.-J. Yoon 《Monthly notices of the Royal Astronomical Society》2004,349(4):1493-1499

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湖南武陵山片区农民收入多样性特征及其对贫困的影响   总被引：4，自引：3，他引：1  

丁建军  宁燕 《地理科学》2016,36(7):1027-1035

应用探索性和验证性定量分析方法,测度并探讨了2000~2012年间湖南武陵山片区农民收入多样性的时空演变特征及其对贫困的影响。研究发现,湖南武陵山片区农民收入的多样性程度不高且呈现“先降后升”的趋势,不同县市区间农民收入多样性程度差距不断缩小;多样性程度相似县市区在少数年份呈现出空间集聚而在大多数年份为随机分布;片区内娄邵片区、张家界片区农民收入多样性程度相对较高,怀化片区最低,湘西州片区则提升幅度最大,整体上高多样化县市区向娄邵片区和湘西州片区集中;局部空间格局中高-高（HH）、低-高（LH）类型有较大的空间迁移,而高-低（HL）、低-低（LL）类型在空间上分布相对稳定且大多数年份驻留在怀化片区,湘西州片区内县市区跨空间格局类型变迁最为剧烈;农民收入多样性对增加农民收入、降低贫困有着十分显著的影响。  相似文献