This Yellow Swirl Could Be the Birth of a New Planet

This image shows the disc around the young AB Aurigae star, where ESO’s Very Large Telescope (VLT) has spotted signs of planet birth. Close to the centre of the image, in the inner region of the disc, we see the ‘twist’ (in very bright yellow) that scientists believe marks the spot where a planet is forming. This twist lies at about the same distance from the AB Aurigae star as Neptune from the Sun. The image was obtained with the VLT’s SPHERE instrument in polarised light.

Scientists have identified thousands of exoplanets thanks to instruments like the Kepler Space Telescope. With each new world we examine, we learn more about how planets develop across the universe. Studying planets as they form would be the holy grail, and astronomers may have spotted a place where we can do just that. The European Southern Observatory (ESO) has released images of a primordial solar system with swirls of gas that could be the beginning of planetary formation

Astronomers have good evidence that planetary formation takes place in the disc of dust and gas around young stars, but they’ve never been able to take sufficiently sharp images to identify the small eddies that signify a planet is coming into existence. Several years ago, the Large Millimeter/submillimeter Array (ALMA) scanned a star called AB Aurigae, located 520 light-years away from Earth. The data suggested this young star might have small disturbances in the primordial disc suggesting planetary formation. The ESO sought to confirm that with the Very Large Telescope (VLT). 

The VLT has a relatively new adaptive optics instrument called SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch). This allows the telescope to capture higher quality images with better contrast, but only in a very narrow field of view. That’s perfect for taking a close look at a single star, though. The ESO conducted an observational campaign of AB Aurigae in late 2019 and early 2020, resulting in the newly released images. 

The images of the AB Aurigae system showing the probable location of a forming exoplanet.

The orange swirl is the dust and gas orbiting AB Aurigaem. The dark region near the center is about the size of Neptune’s orbit around the sun — even with SPHERE, we can’t zoom in beyond this level without losing detail. However, it’s sufficient to make out a probably baby planet. The brighter “twist” highlighted above is precisely what astronomers expected a planet might look like at this stage of development. Over eons, material will gather together, exerting gravitational influence on nearby space. Eventually, it bulks up and becomes spherical by absorbing everything else in its orbit, and then it’s what we’d call a planet. 

The ESO is currently building the 39-meter Extremely Large Telescope (they’re clearly great at naming things) to build on the work of LAMA and SPHERE. When it comes online in 2025, the Extremely Large Telescope should be able to take a closer look at this probably infant exoplanet. The upcoming James Webb Space Telescope could also take a closer look. It will have a smaller mirror, but its vantage point in orbit will be much better.

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