Out of this world... a planet is born
Scientists witness and photograph for the first time a planet’s formation, 370 light years from Earth
EVEN by astronomical standards it is a discovery that is out of this world. Scientists have for the first time witnessed the birth of a planet, a huge gas giant many times the size of Jupiter, swirling into existence 370 light years from Earth.
The theory of how gas planets form from a vortex of hydrogen and helium molecules captured by their own gravity is now widely accepted by scientists. But it has never been seen before, until now. Today scientists at the Max Planck Institute for Astronomy (MPIA) in Heidelberg and the Sphere instrument consortium at the Very Large Telescope of the European Southern Observatory (ESO) in Chile, released a spectacular image of the birth.
The planet, known as PDS 70b, is shown orbiting within a huge spinning “protoplanetary disc” of gas and dust, which proves it is continuing to accumulate matter, and so is not yet fully formed.
The newborn sits within a 5.4million-year-old solar system, orbiting a star called PDS 70. The planet stands out clearly in the image, visible as a bright point to the right of the blackened centre.
The dark region at the centre of the image is due to a coronagraph, a mask which blocks the blinding light of the central star and allows astronomers to detect the faint light from the planet.
“For our study, we selected PDS 70, a star that was already suspected of having a young planet circling around it,” says Miriam Keppler, doctoral student at MPIA.
“These discs around young stars are the birthplaces of planets, but so far only a handful of observations have detected hints of baby planets in them.
“The problem is that until now, most of these planet candidates could just have been features in the disc.”
This glimpse of the dust-shrouded birth of a planet was only possible because of ESO’S Sphere instrument, which studies exoplanets and discs around nearby stars using a technique known as high-contrast imaging. Using the instrument, astronomers were able measure the brightness of the planet at different wavelengths, and find out its composition. It is located roughly 1.8billion miles from the central star, roughly
‘The results give us a new window on to the complex and poorly understood early stages of planetary evolution’
equivalent to the distance between Uranus and the Sun. The planet takes about 120 years to orbit its host star.
Spectral analysis shows PDS 70b is a giant gas planet, with a mass a few times that of Jupiter and a surface temperature of around 1,830F (1,000C), making it much hotter than any planet in our own solar system. Thomas Henning, director at the Max Planck Institute and leader of the teams, summarised the scientific adventure: “After more than a decade of enormous efforts to build this hi-tech machine, now Sphere enables us to reap the harvest with the discovery of baby planets.”
To date, astronomers have discovered around 3,800 exoplanets outside of the solar system, but have never seen one being born.
“The results give us a new window onto the complex and poorly-understood early stages of planetary evolution,” said Dr André Müller, leader of the second team to investigate the young planet. “We needed to observe a planet in a young star’s disc to really understand the processes behind planet formation.”