科学家首次观测到行星形成过程

An international team of scientists in Australia and the United States has captured the first-ever images of a planet in the making. The accumulation of dust and gas particles onto a new planet - the process by which the planet continues to form and grow - has been directly observed for the first time. None of the nearly 1,900 planets previously discovered and confirmed outside our Solar System (called exoplanets) are in the process of formation.

The findings of the scientists, led by University of Arizona graduates Steph Sallum and Kate Follette and including the University of Sydney's Professor Peter Tuthill, are published today in Nature. 

The YouTube video can be shared after the embargo lifts at https://www.youtube.com/watch?v=vp37oQgTmX4.

A star known as LkCa 15, located 450 light years from Earth, has been observed exhibiting all the trappings of an expectant parent: it is surrounded by a vast disc of dust and gas, making an ideal environment for planets to grow from; the dust shows distinct signs of disturbance - something within has eaten away part of the disc. 

Co-author of the paper, Professor Tuthill, said the images provided unambiguous evidence. "This is the first time we've imaged a planet that is definitely still in the process of forming."

The photo provided the proof: "The difficulty had been that when you have indirect evidence, there are always alternate explanations that might fit the data," Professor Tuthill said.

Researchers are just now being able to image objects that were close to and much fainter than a nearby star, thanks to specialised instruments. These include the Large Binocular Telescope - the world's largest telescope, located on Arizona's Mount Graham - and the University of Arizona's Magellan Telescope and its Adaptive Optics System, MagAO, located in Chile.