1,720,976 research outputs found
Orion Nebula - High resolution Pa-12 mapping
No full textA detailed map of the Paschen-12 (8750 A) line intensity across the central regions of the Orion Nebula is presented which was derived from observations with a tilting-filter Fabry-Perot interferometer mounted at the Cassegrain focus of a 182-cm telescope. The Pa-12 fluxes are compared with an H-alpha photograph and detailed H-alpha intensity tracings of the same regions in order to determine the variation of absorption in the different areas. Using recombination-line theory, it is found that the H-alpha absorption exceeds that in Pa-12 by 0.60 (plus or minus 0.20) magnitude over most of the visible nebula. The mottled appearance of the nebula is attributed to density variations of the gas inside the H II region and to nonuniformities in the dust distribution. Normalized column densities of the absorbing dust toward the Trapezium are plotted as a contour map, and interesting features in other areas are noted. It is concluded that the reddening law for starlight and nebular emission is the same
Orion Nebula - Fabry-Perot high resolution O I /8446 A/ mapping
No full textThe Fabry-Perot near-infrared spectrophotometer of the 182-cm Asiago telescope was used for absolute flux measurements of the neutral oxygen line at 8446 A in 22 positions across the surface of the Orion Nebula (M42). From the derived O I/H-beta ratios, starlight excitation appears to be the most efficient mechanism for explaining the unexpected strength of this line
Esperimenti con fasci molecolari nel Laboratorio di Fisica Cosmica dell'Università di Lecce
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Comet Ikeya-Zhang (C/2002 C1): Determination of the Rotation Period From Obervations of Morphological Structures
No full textHigh quality CCD images allowed the identification of several morphological structures near the nuclear zone of comet Ikeya-Zhang. The interpretation of these structures led to an estimate of its rotation period
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