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

Rui-Qing Mao  Qin Zeng Purple Mountain Observatory  Chinese Academy of Sciences  Nanjing  National Astronomical Observatories  Chinese Academy of Sciences  Beijing 《中国天文和天体物理学报》2004,4(5):440-454

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#m dust continuum. Four submillimeter continuum sources, labelled SMM 1-4, are revealed in the 870μm 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 870μm 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.  相似文献   

Intranight optical variability of blazars   总被引：1，自引：0，他引：1  

Ram Sagar  C. S. Stalin  Gopal-Krishna  Paul J. Wiita 《Monthly notices of the Royal Astronomical Society》2004,348(1):176-186

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Analysis of two scenarios for the early optical emission of the gamma-ray burst afterglows 990123 and 021211     

A. Panaitescu  P. Kumar 《Monthly notices of the Royal Astronomical Society》2004,353(2):511-522

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Outflowing material in the compact steep-spectrum source quasar 3C 48: evidence of jet–cloud interaction?     

Neeraj Gupta  R. Srianand  D. J. Saikia 《Monthly notices of the Royal Astronomical Society》2005,361(2):451-459

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Rapid variability of the arcsec-scale X-ray jets of SS 433     

S. Migliari  R. P. Fender  K. M. Blundell  M. Méndez  M. van der Klis 《Monthly notices of the Royal Astronomical Society》2005,358(3):860-868

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CHEMICAL CHARACTERISTICS OF WETLAND′S INFLOW DRY DIFFUSE DUST AND DIRT FROM IMPERVIOUS SURFACE     

Azam Khan  Saadat Ashraf 《湿地科学》2005,(4)

1INTRODUCTIONIn impervious area dry dustand dirtbuildup con-tains heavy metals,nutrients,pesticides and organ-ics.Many studies(APWA,1969;Sartor and Boyd,1972;Pitt and Amy,1973;Pitt,1979,1985;Yousef and Wanielista,1990;Wanielista andYousef,1993,Ball,et al.…  相似文献   

Emission lines and optical continuum in low-luminosity radio galaxies     

K. A. Wills  R. Morganti  C. N. Tadhunter  T. G. Robinson  M. Villar-Martin 《Monthly notices of the Royal Astronomical Society》2004,347(3):771-786

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Relativistic models of two low-luminosity radio jets: B2 0326+39and B2 1553+24   总被引：1，自引：0，他引：1  

J.R. Canvin  R. A. Laing 《Monthly notices of the Royal Astronomical Society》2004,350(4):1342-1365

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On the Nature of the Variable Gamma-Ray Sources at Low Galactic Latitudes     

Valentí Bosch-Ramon  Gustavo E. Romero  Josep M. Paredes 《Astrophysics and Space Science》2005,297(1-4):119-129

Population studies of EGRET gamma-ray sources indicate that there is a distinctive population of bright sources at low galactic latitudes. The sources have a distribution consistent with that of young galactic objects, with a concentration toward the inner spiral arms. There is a subgroup that displays strong variability with timescales from days to months. Following an earlier suggestion by Kaufman Bernadó et al. (2002), we explore the possibility that these sources could be high-mass microquasars. Detailed models for the gamma-ray emission that include inverse Compton interactions of electrons in the relativistic jets and photons from all local fields (stellar UV photons, synchrotron photons, soft X-ray photons from the accretion disk, and hard X-ray photons from a corona) are presented. We conclude that microquasars are excellent candidates for the parent population of the subgroup of variable low-latitude EGRET sources.  相似文献   

The Large-Scale, Decelerating X-ray Jets from the Microquasar Xte J1550−564: Evidence for External Shocks Caused by the Jet-Ism Interaction?     

X. Y. Wang  Z. G. Dai  T. Lu 《Astrophysics and Space Science》2005,297(1-4):155-166

Large-scale, decelerating, relativistic X-ray jets from microquasar XTE J1550−564 has been recently discovered with Chandra by Corbel et al. (2002). We find that the dynamical evolution of the approaching jet at the late time is consistent with the well-known Sedov evolutionary phase R∝ t ^2/5. A trans-relativistic external shock dynamic model by analogy with the evolution of gamma-ray burst remnants, is shown to be able to fit the proper-motion data of the approaching jet reasonably well. The inferred interstellar medium density around the source is well below the canonical value n _ISM∼1 cm⁻³. The rapidly fading X-ray emission can be interpreted as synchrotron radiation from the non-thermal electrons in the adiabatically expanding ejecta. These electrons were accelerated by the reverse shock (moving back into the ejecta) which becomes important when the inertia of the swept external matter leads to an appreciable slowing down of the original ejecta.  相似文献