New photos of the Pencil Nebula

By Paul Harper

A new image of the Pencil Nebula - a.k.a NGC 2736 - has been captured by an observatory in Chile. Photo / La Scilla Observatory

An observatory in Chile has captured a new image of the Pencil Nebula - a cloud of glowing gas which resembles a witch's broom.

The European Southern Observatory's La Silla Observatory captured the image of the nebula, also known as NGC 2736, which is part of a huge ring of wreckage left over after a supernova explosion that took place about 11, 000 years ago.

The image was produced by the Wide Field Imager on the MPG/ESO 2.2-metre telescope, ESO said.

"The brightest part resembles a pencil; hence the name, but the whole structure looks rather more like a traditional witch's broom," ESO said in a statement.

"The Vela supernova remnant is an expanding shell of gas that originated from the supernova explosion. Initially the shock wave was moving at millions of kilometres per hour, but as it expanded through space it ploughed through the gas between the stars, which has slowed it considerably and created strangely shaped folds of nebulosity.

"The Pencil Nebula is the brightest part of this huge shell."

The Pencil Nebula was discovered in 1835 by British astronomer John Herschel, who described it as "an extraordinary long narrow ray of excessively feeble light".

"This new image shows large, wispy filamentary structures, smaller bright knots of gas and patches of diffuse gas," ESO said.

"The nebula's luminous appearance comes from dense gas regions that have been struck by the supernova shock wave. As the shock wave travels through space, it rams into the interstellar material. At first, the gas was heated to millions of degrees, but it then subsequently cooled down and is still giving off the faint glow that was captured in the new image."

ESO said astronomers have been able to map the temperature of the gas by looking at the different colours of the nebula in the image. The glowing blue streak is gas still so hot that the emission is dominated by ionised oxygen atoms, while the cooler areas appear red, due to the emission of hydrogen.

The Pencil Nebula measures about 0.75 light-years across and is moving through the interstellar medium at about 650 000 kilometres per hour.

Even though the formation is about 800 light-years from Earth, its position in the night sky changes relative to the background stars over the course of a human lifetime.

A supernova is a violent stellar explosion following the death a high-mass star or a white dwarf in a close double star system.

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