Stirred-up planet factory revealed

All planets, including the ones in our Solar System, are born in disks of gas and dust around stars, so-called protoplanetary disks

Image Credits: ALMA (ESO/NAOJ/NRAO), J. Huang; NRAO/AUI/NSF, S. Dagnello.

Planet-forming environments can be much more complex and chaotic than previously expected.

This is evidenced by a new image of the star RU Lup, made with the Atacama Large Millimeter/submillimeter Array (ALMA).

All , including the ones in our Solar System, are born in disks of gas and dust around stars, so-called . Thanks to ALMA we have stunning  of many of these planet factories, showing  with multiple rings and gaps that hint at the presence of emerging planets. The most famous examples of these are HL Tau and TW Hydrae.

But disks are not necessarily as neatly arranged as these initial dust observations suggest. A new ALMA image of RU Lup, a young variable star in the Lupus constellation, revealed a giant set of spiral arms made of gas, extending far beyond its more well-known dust disk. This spiral structure—resembling a ‘mini-galaxy’ – extends to nearly 1000 astronomical units (au) from the star, much farther away than the compact dust disk that extends to about 60 au.

Previous observations of RU Lup with ALMA, which were part of the Disk Substructures at High Angular Resolution Project (DSHARP), already revealed signs of ongoing planet formation, hinted by the dust gaps in its protoplanetary disk. “But we also noticed some faint carbon monoxide (CO) gas structures that extended beyond the disk. That’s why we decided to observe the disk around the star again, this time focusing on the gas instead of the dust,” said Jane Huang of the Center for Astrophysics, Harvard & Smithsonian (CfA) and lead author on a paper published today in the Astrophysical Journal.



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