The Dumbbell Nebula M 27 is an extraordinarily large planetary nebula, not only because it is not even 1,000 light years close to us, but also because it has a considerable real extension of about 2.5 light years. However, exact details of such objects with regard to their distance are always associated with a degree of uncertainty. According to spectroscopic measurements, M 27 expands at a speed of 27.3 km/s, which indicates its unusually high age of around 48,000 years.
With a surface temperature of 85,000 K, the central star in M 27 is a typical white dwarf with about half the luminosity of our sun. One suspects, however, that it could be a binary system. Its companion, a yellow dwarf of 17th magnitude, is about 6,5″ in southwestern direction and can be seen on the picture.
The Dumbbell Nebula is immediately noticeable even in smaller instruments from 60 mm upwards. The eyepiece of a 14″ SCT shows a magnificent and unusually bright planetary nebula at low magnification (100x), from which it is difficult to tear oneself away.
Picture & Text: Rald Schmidt, member of the STScI
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