For the first time, researchers have photographed the birth of a distant planet.
Of the nearly 2,000 exoplanets we know about, only 10 or so have been imaged before, and all had long been finished becoming planets. Astronomers have also seen hints of planets forming, but scientists had never imaged a planet in the middle of its formation. The photograph, published in the journal Nature this week, provides a glimpse into how solar systems come into being.
A glimpse into how solar systems come into being
This exoplanet in the making orbits a young star called LkCa15, located 450 light years from Earth. Surrounding LkCa15 is a huge, protoplanetary disk — a rotating saucer of dense gas that typically encompasses young stars. Protoplanetary disks form out of the dust and debris left over when a star is born. It's within these disks that planets form; some of the materials coalesce into larger objects, and then create gaps in the dust cloud where the new planets reside.
A composite image shows the planet in motion around the star. (UA / Nature)
The protoplanetary disk around LkCa15 is unique because it contains an exceptionally large gap. "It’s like a big doughnut," said study author Kate Follette, a former University of Arizona graduate who studied the planet, said in a statement. "This system is special because it’s one of a handful of disks that has a solar-system size gap in it. And one of the ways to create that gap is to have planets forming in there."
Follette and Sallum observed the LkCa15 system using Arizona's Large Binocular Telescope, the world’s largest telescope, and the University of Arizona's Magellan Telescope, found in Chile. The Magellan Telescope has a special adaptive optics system that was able to pick up the planet's "hydrogen alpha" light — a specific wavelength of light that stars and planets emit as they grow. These cosmic objects get really hot when they form, causing their hydrogen components to glow a deep red that can be observed from Earth.
The researchers were able to separate the hydrogen alpha light coming from the star, to get the image of the emerging exoplanet. But the scientists couldn’t see everything — and they think there may be more planets in the gap of the protoplanetary disk.