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《天文和天体物理学研究(英文版)》2014,(8)
We present large scale observations of C18O(1–0) towards four massive star forming regions: MON R2,S156,DR17/L906 and M17/M18. The transitions of H2CO(110–111),C18O(1–0) and the 6 cm continuum are compared in these four regions. Our analysis of the observations and the results of the Non–LTE model shows that the brightness temperature of the formaldehyde absorption line is strongest in a background continuum temperature range of about 3 – 8 K. The excitation of the H2 CO absorption line is affected by strong background continuum emission. From a comparison of H2 CO and C18 O maps,we found that the extent of H2 CO absorption is broader than that of C18 O emission in the four regions. Except for the DR17 region,the maximum in H2 CO absorption is located at the same position as the C18 O peak. A good correlation between intensities and widths of H2 CO absorption and C18 O emission lines indicates that the H2 CO absorption line can trace the dense,warm regions of a molecular cloud. We find that N(H2CO) is well correlated with N(C18O) in the four regions and that the average ratio of column densities is N(H2CO)/N(C18O) ～ 0.03. 相似文献
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May I first express my warmest thanks to the organizers of the Conference for having invited me to present a brief bibliographic report on the great astronomer F. W. Bessel. You have given me a welcome opportunity to express an appreciation of Bessel's work which has marked the beginning of research on the motion of stars and which was pioneer work on astrometric binaries and on the determination of stellar distances. Bessel has established the first celestial coordinate system which approximates an inertial system, and my colleagues and I at Heidelberg in establishing an improved fundamental reference system, the FK5, have had to review again some of Bessel's pioneer contributions to this field, and such contributions shall be mentioned later. My talk shall be divided into the following parts: (1) Bessel's course of life and family; (2) Education in astronomy in Bremen; (3) Fundamenta Astronomiae; (4) Fundamental observations at the Königsberg Observatory (or according to S. Newcomb (1906): the German School of Astrometry); (5) 61 Cygni; (6) Bibliography of Bessel's original works.Communication presented at the International Conference on Astrometric Binaries, held on 13–15 June, 1984, at the Remeis-Sternwarte Bamberg, Germany, to commemorate the 200th anniversary of the birth of Friedrich Wilhelm Bessel (1784–1846). 相似文献
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This paper deals with molecular clouds discovered in the absorption spectra (z=2–3) of distant quasars. It is argued that these clouds belong to the gaseous subsystems of young galaxies. We estimate the gas concentration to ben<104 cm–3 in the cloud observed in the direction of the quasar PHL957. It is shown that this cloud is exposed to ultraviolet radiation. The UV-energy flux does not exceed the value typical for our Galaxy by an order of magnitude (F2×10–6 ergs cm–2 s–1 Å–1 at =2000 Å). The mechanisms maintaining the thermal balance in this cloud are discussed. 相似文献
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We present a photometric calibration of the SOHO/LASCO-C2 coronagraph based on the analysis of all stars down to magnitude V=8 that transited its field of view during the past 14 years of operation (1996?–?2009), extending the previous work of Llebaria, Lamy, and Danjard (Icarus 182, 281, 2006). The pre-processing of the images incorporates the most recent determination of the evolution of the LASCO-C2 performances. The automatic procedure then analyzes some 260?000 images to detect, locate, and measure those stars. Aperture photometry is performed using four different aperture sizes, and the zero points (ZPs) of the photometric transformations between the LASCO-C2 magnitudes for its orange filter and the standard V magnitudes are determined after introducing a correction for the color of the stars. A new statistical method (“bootstrap”) is introduced to assess the confidence intervals of the mean yearly value of the ZPs. The correction for finite aperture required to derive the calibration coefficient for the surface photometry of extended sources is based on the reconstructed image of bright saturated stars and a robust model for the growth curve. The global temporal evolution of the sensitivity of LASCO-C2 is compatible with a continuous decrease at a rate of ≈?0.56 % per year. However, it is better described by two separate linear variations with a discontinuity at the time of the loss of SOHO. After the resumption of normal operations in 1999, the linear decrease of the sensitivity amounts to ≈?0.35 % per year. 相似文献
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Obituary
OBITUARY: Mukul Kundu (1930 – 2010) 相似文献11.
Alain Hui-Bon-Hoa 《Astrophysics and Space Science》2008,316(1-4):55-60
In the framework of the CoRoT-ESTA, we present the Toulouse–Geneva Evolution Code (TGEC) at its present stage. 相似文献
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《New Astronomy Reviews》1999,43(8-10):599-602
The position of PSR0329+54 on the International Celestial Reference Frame was measured at epochs March 1995, May 1996, and May 1998. Our observations detected the proper motion of PSR0329+54. The position and proper motion agreed well with the position determined by Bartel et al. (1985). From combined analysis with our data and that of Bartel, the proper motion of PSR0329+54 was determined: μα=+17.4±0.3 mas yr−1, μδ=−11.0±0.3 mas yr−1. These results are consistent with the value by Harrison et al. (1993)measured with the MERLIN interferometer. We also determined the coordinates of PSR0329+54 very accurately within the ICRF: α=03h32m59s.3761±0s.0002, δ=54°34′43′′.5119±0′′.0015 at 1995. 相似文献
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二 中学时代(1915-1919) 家世(二) 母亲去世,我们兄弟姐妹五人由舅母抚养。父亲又娶,继母生三男。三弟早亡,六弟和继母在抗战时被炸身亡。生存到解放后的,只有我、三个弟弟和姐妹二人。 姐姐陈璧如长我两岁,北京女子师范大学中文系毕业,早年(1926年)即参加革命。曾在南京、北京等大城市做地下工作;去延安、随军南下;后调入中共中央农村工作部,1977年初逝世于北京。 相似文献
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V. M. S. Carrasco J. M. Vaquero A. J. P. Aparicio M. C. Gallego 《Solar physics》2014,289(11):4351-4364
A sunspot catalogue was maintained by the Astronomical Observatory of Valencia University (Spain) from 1920 to 1928. Here we present a machine-readable version of this catalogue (OV catalogue or OVc), including a quality-control analysis. Sunspot number (total and hemispheric) and sunspot area series are constructed using this catalogue. The OV catalogue data are compared with other available solar data, demonstrating that the present contribution provides the scientific community with a reliable catalogue of sunspot data. 相似文献
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《时间频率公报》1997,(1)
UTC(CSAO)一GPS TIME1997年l月 日MJDPRN 22拌5 UTPRN 24拼5 UTPRN 25料5 UTPRN 26娜UTPRN 27拌5 UTPRN 29娜UT044904500451045204530.431(0546)0.395(0506)0.366(0502)0.414(0458)0.429(2107)0.446(2059)0.314(0902)0,376(0126)一一 一一0.341(2222)一0.412(0818)0.423(0052)0.406(2218)0.361(0730)0.348(0814)0.407(0046)0.384(2214)0.346(0726)0.422(0810)0.503(0042)0.360(2210)0.412(0722)045404550456045704580.472(0454)一0.409(0806)0.493(0038)0.462(2206)0.425(0718)0.421(0450)一0.433(0802)0.405(0034)0.442… 相似文献