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61.
Marcella Contini 《Astrophysics and Space Science》1995,233(1-2):261-266
AGN spectra are investigated by comparing model calculations with observations. Line intensity ratios show that the emitting gas is heated by shocks. Therefore, composite models which consistently account for both shocks, accompanying the radial motion of the gaseous clouds, and a photoionizing radiation flux are used. Liners are ambiguous objects between AGN and Starburst galaxies, therefore, power-law or black body radiations are considered in the models, depending on the characteristics of the line spectra. The SUMA code is used.The results show that shocks definitively play an important role, even if a photoionizing flux is generally present. Particularly, the heterogeneous nature of the objects, which are classified as Liners, is confirmed. 相似文献
62.
Paul Jacob Hancock Paul Roberts Michael J. Kesteven Ronald D. Ekers Elaine M. Sadler Tara Murphy Marcella Massardi Roberto Ricci Mark Calabretta Gianfranco de Zotti Philip G. Edwards Jennifer A. Ekers Carole A. Jackson Mark Leach Chris Phillips Robert J. Sault Lister Staveley-Smith Ravi Subrahmanyan Mark A. Walker Warwick E. Wilson 《Experimental Astronomy》2011,32(2):147-177
The Australia Telescope 20 GHz (AT20G) survey is a large area (2?? sr), sensitive (40 mJy), high frequency (20 GHz) survey of the southern sky. The survey was conducted in two parts: an initial fast scanning survey, and a series of more accurate follow-up observations. The follow-up survey catalog has been presented by Murphy et al. (MNRAS 402:2403, 2010). In this paper we discuss the hardware setup and scanning survey strategy as well as the production of the scanning survey catalog. 相似文献
63.
The modeling of UV and optical spectra emitted from the symbiotic system AG Dra, adopting collision of the winds, predicts soft X-ray bremsstrahlung from nebulae downstream of the reverse shock with velocities > 150 km s?1 and intensities comparable to those of the WD black body flux. At outbursts, the envelop of debris, which corresponds to the nebula downstream of the high velocity shocks (700–1000 km s?1) accompanying the blast wave, absorbs the black body soft X-ray flux from the WD, explains the broad component of the H and He lines, and leads to low optical-UV–X-ray continuum fluxes. The high optical-UV flux observed at the outbursts is explained by bremsstrahlung downstream of the reverse shock between the stars. The depletion of C, N, O, and Mg relative to H indicates that they are trapped into dust grains and/or into diatomic molecules, suggesting that the collision of the wind from the WD with the dusty shells, ejected from the RG with a ~1 year periodicity, leads to the U-band fluctuations during the major bursts. 相似文献
64.