My thanks to Terry Moseley of the Irish Astronomical Association for letting me know about this.
All astronomers know that Planetary Nebulae have absolutely nothing to do with planets: the name is an unfortunate legacy from the 19th century when poorer quality telescope optics failed to resolve these objects properly, making them look like planets. The best known example is probably the Ring Nebula, M57, in Lyra.
With the authority of Sir William Herschel behind the original appellation, no-one dared to change it, even when it became obvious that these objects are in fact shells of gas given off by certain stars at a late stage in their evolution. But it has been recognised that the time has come to drop that inappropriate and misleading name, and come up with something more accurate.
Part of the impetus for this change came from the International Astronomical Union’s (IAU) decision to officially rename Pluto and Ceres as ‘Dwarf Planets’. Now a new name for these objects has also to be found.
Spokesperson Olaf Pirol said “Now is an appropriate time to get rid of this anomaly and give these fascinating and often beautiful objects a more appropriate name.”
An obvious one would be ‘Shell Stars”, but this name is already applied to the Gamma Cassiopeia variables (GCAS).
Favourites so far include “Circumstellar Shells” as this is the simplest and most accurate description, because the name in fact applies to the surrounding gas, rather than the star itself.
Another one being considered is “Shell nebulae” which has the advantage of retaining the term ‘nebula’. Or they could be combined into Circumstellar Shell Nebulae: this is longer*, but could be abbreviated to “CSN”.
If agreement cannot be reached, the final decision will probably be taken via a vote among the professional astronomical community.
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Filed under: Deep Space
