Stunning array of 400 rings in a 'reflection' nebula solves a 30-year-old star-formation mystery — Space photo of the week

Go outside after dark this winter and look to the southeast, and you'll see some of the brightest stars in the night sky — Orion's Belt, Betelgeuse, Sirius, Aldabaran and Capella. Just above this melee is the quieter constellation Perseus, which lacks bright stars but hosts something extraordinary that the naked eye can't see — the explosive birth of new stars.

Lurking within the Perseus Molecular Cloud is NGC 1333, nicknamed the Embryo Nebula because it contains many young, hot stars that are teaching astronomers just what goes on when a star is born. NGC 1333 is a reflection nebula, meaning a cloud of gas and dust illuminated by the intense light coming from newly forged stars, some of which appear to be regularly spewing jets of matter. It's one of the closest star-forming regions to our solar system. On Dec. 16. astronomers published the most detailed images ever of a jet launched by a newborn star, called SVS 13, which revealed a sequence of nested, ring-like structures. The finding is evidence that the star has been undergoing an outburst — releasing an immense amount of energy — for decades.

The discovery, which the researchers described in the journal Nature Astronomy, marks the first direct observational confirmation of a long-standing theoretical model of how young stars feed on, and then explosively expel, surrounding material.

The researchers captured the high-resolution, 3D view of a fast-moving jet emitted from one of SVS 13's young stars using the Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope array in Chile. Within the image, they identified more than 400 ultra-thin, bow-shaped molecular rings. Like tree rings that mark the passage of time, each ring marks the aftermath of an energetic outburst from the young star's early history. Remarkably, the youngest ring matches a bright outburst seen in the SVS 13 system in the early 1990s, allowing researchers to directly connect a specific burst of activity in a forming star with a change in the speed of its jet. It's thought that sudden bursts in jet activity are caused by large amounts of gas falling onto a young star.

"These images give us a completely new way of reading a young star's history," said study co-author Gary Fuller, a professor at the University of Manchester. "Each group of rings is effectively a time-stamp of a past eruption. It gives us an important new insight into how young stars grow and how their developing planetary systems are shaped."

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