Australasian Science: Australia's authority on science since 1938

Soccer Ball Nebula Undermines Theory

By Stephen Luntz

The confirmation of a planetary nebula, recently discovered by amateurs, may lead to the overthrow of an astronomical theory that is currently taught as confirmed knowledge.

In 1994 photographic plates of the entire northern sky taken with the giant Mt Palomar telescope in California were digitised, allowing their widespread access, and a group of amateurs known as the Deep Sky Hunters set about combing the plates for new objects such as nebulae. The Hunters have come up with around 100 planetary nebulae, but the object Kn61 could prove unusually significant as a result of its location in the sky.

Kn61 was found by Matthias Kronberger and lies in an area of Lyra that is part of the field monitored by the Kepler space telescope. Kepler is monitoring the brightness of 145,000 stars within this field, looking for the faint fluctuations in light that could be the result of a planet crossing in front of a star.

While Kepler’s main role is to search for Earth-sized planets around other stars, it also checks the stars at the centre of planetary nebulae within its field. Contrary to their names, planetary nebulae are huge balls of gas thrown off by giant stars.

“The question is whether planetary nebulae are the deaths of common stars – as we teach our undergrads,” says A/Prof Orsola De Marco of Macquarie University. A rival theory holds that the nebulae are caused by the interactions between binary companions.

“The problem is that the dominant theory suggests planetary nebulae should be spherical,” De Marco says, “but the majority are bipolar or elliptical”. As with planets, Kepler can detect small companion stars crossing the face of much brighter stars, and if this occurs in enough cases the textbooks may need rewriting.

By seeking companions for the nebulae within the Kepler field, De Marco hopes this question may be answered. “Three nebulae were known within the field, but three more have now been found – one unconfirmed,” De Marco says. “Hopefully there will be more before we finish. Every extra nebula in the field increases our chances of resolving this issue.”

When Kronberger alerted the world to the possibility that Kn61 might be a nebula, De Marco used the Kitt Peak National Observatory’s 2.1-metre telescope to confirm the finding. Subsequently an image taken with the Gemini North telescope revealed the object’s beauty.