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|Merged catalogue of reflection nebulae|
Several catalogues of reflection nebulae are merged to create a uniformcatalogue of 913 objects. It contains revised coordinates,cross-identifications of nebulae and stars, as well as identificationswith IRAS point sources.The catalogue is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/399/141
|Briefly noted: Irish astronomy (poem)|
|The surface brightness of reflection nebulae - NGC 1432 and the 17 Tauri nebulosity|
New photoelectric surface brightness measurements of the reflectionnebulae near 20 Tau and 17 Tau are reported for intermediate widthbandpasses centered near 3500, 4100, 4700, and 5500 A. The derivedsurface brightness distributions have been used to set limits on thedensity and the spatial extent of the dust clouds near these stars. NGC1432 (20 Tau) can be represented successfully by either an inclinedplane-parallel dust slab with the star in front or by an extended,optically thin spherical shell surrounding 20 Tau. The 17 Tau nebulosityis most easily modelled by an extended spherical cloud of low uniformdensity. A comparison of the absolute surface brightness of fourreflection nebulae, NGC 7023, NGC 1435, NGC 1432, and the 17 Taunebulosity, shows the latter two to be relatively inefficient producersof scattered light.
|IUE observations of reflection nebulae|
Low-resolution IUE spectra in the SWP and LWR ranges were obtained ofseveral reflection nebulae in the vicinity of their respectiveilluminating stars. Data for NGC 7023 (HD200775), NGC 1435 (Merope, 23Tau), NGC 1432 (Maia, 20 Tau) and the Electra (17 Tau) nebula were foundto display significant differences in the shape of their normalizednebular spectra. If the dust in these nebulae is similar from one objectto the next, these differences can be most readily explained bydifferences in the line-of-sight dust distribution, coupled with awavelength-dependent phase function, changing from a strongly forwardthrowing form (g = 0.6-0.7) in the visible to a more nearly isotropicshape (g approximately 0.25) at 1400A.
|Studies of bright diffuse galactic nebulae with special regard to their spatial distribution.|
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