... new infrared spectra of the evolved planetary nebula NGC 6445 obtained with ISO ... We also argue that dust-gas separation in the nebula is not plausible. ... of the silicon-bearing grains in this nebula were able to survive exposure to hard ...
... small-scale and short-lived dark features in Ca II H chromospheric filtergrams and ... release in the low chromospheric line is detected while the dark features are fading ...