One of 42 new protoplanetary discs discovered in the Orion Nebula. The tadpole-shaped tail is actually a jet of matter flowing away from the centre of the disc.
Credit: NASA/ESA and L. Ricci (ESO)
SYDNEY: Researchers have released the first complete atlas of embryonic planetary systems in the Orion Nebula – and discovered 42 new ones in the process.
Protoplanetary discs, also known as proplyds, are made of gas and dust particles that gravitate around a newborn star. It is thought that new planets form in these discs when the tiny dust particles combine.
The researchers at the European Southern Observatory in Germany compiled the high-resolution atlas of all the proplyds in the Orion Nebula using images from Hubble's Advanced Camera for Surveys.
In doing so, they not only identified 42 previously unknown discs, they were also able to differentiate two different types of disc - those close to the brightest star in the cluster, and those furthest away.
Life-friendly regions
The more distant proplyds, which included many of the newly discovered discs, were identified in silhouette against backlighting provided by the nebula itself. These proplyds are considered more "life-friendly" since they're not reached by the violent UV photons emitted by the cluster's central massive star, called Theta 1 Orionis C.
Following the release of the images, the researchers plan to use the Hubble Space Telescope to observe the discs at longer wavelengths, such as the infrared.
"At these wavelengths several interesting properties of the dust grains can be studied," said lead researcher Luca Ricci, of the European Southern Observatory. "For example we will be able to probe the sizes of these dust grains, and see if they have grown to pebbles or stones.
"In this way we investigate which stage the dust grain growth process has reached and better understand the likelihood of the formation of a planetary system similar to our own."
Tadpole planets
Stuart Ryder, an astronomer from the Anglo-Australian Observatory in New South Wales said that the Orion Nebula was an ideal "hunting ground" for proplyds, given its "prodigious rate of new star formation.
"It's remarkable that so many of these proplyds show a tadpole shape, as this does indeed seem to mark the juvenile stage of planet formation," he added.
"However, just as a pond can be both a nurturing and a dangerous environment for tadpoles, the Orion Nebula is clearly not the most benign place for a proplyd," he said, pointing to those forming in close proximity to the central massive star.
"This serves as a timely reminder that, although extra-solar planets are now being found in ever-increasing numbers, it seems not every protoplanetary system survives this stage and that the establishment of life on any such planet would be precarious indeed."
