178-187 (10 pages) ABSTRACT Recent analyses of nebular spectra have resulted in discrepant abundances from CNO forbidden and recombination lines. We consider independent methods of determining ion ...

The spectra of both the star and the nebula show no signs of hydrogen or helium, which is unusual ... infrared wavelengths ...

Where reflection nebulae are cooler clouds illuminated by stars, emission nebulae are their own light source: radiation from ...

Not-so-obscure catalog This week’s second large-telescope target is the 301st emission nebula cataloged by American astronomer Stewart Sharpless in his second catalog of such objects.