A: Low exposure time snapshots of four planetary nebula. B: Spectra of the four planetary nebula. Underneath the spectra an axis is plotted relating the colourimage to the wavelength. Prominent emission lines corresponding to the lines of [WC] stars and planetary nebula are annotated on top of the axis.

After visiting the Wolf-Rayet star WR136 in C27, the [WC] star that is known as Campbell's Hydrogen Star and the planetary nebula C22, aka Blue Snowball, I decided to find out whether [WC] like stars are rare or a common phenomena. Instead of typing "google" in the address bar of my browser I started Stellarium and looked out for some bright yet compact planetary nebula. I also hoped to find targets for astrophotography and further spectroscopy projects. Maybe it is possible to detect oxygen, nitrogen, carbon or hydrogen differently distributed in the nebula with the StarAnalyser100?

I was surprised that C6 and C15 definitely look Wolf-Rayet like and C55 is also characterized by a faint continuous spectrum with emission lines. The lines most likely corresponding to N III, C III or He II between 454 and 465nm and C IV or He I around 580nm indicate a [WC] like star in the center of C55.
I also was pleased to observe many details in the small yet structured objects. Definitely worth visiting with a barlow and more exposure time. When zooming in, jets, protrusions and bubbles can be observed as well as the faint red glow of hydrogen in the edges in two cases. However, the nature of the central star remains a mystery in the snapshots only to be revealed in the spectrum.

After taking the snapshots, the spectra and uploading the image I did a little research and found 11 more PN with [WC] type central stars. I'm curious how many more are out there?


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Photos: approximately 25 to 50 x 4 to 10s light, 10 dark, 25 flats each
Spectra: approximately 25 x 20s light, 10 dark each