Kyushu University researchers have shed new light on an important question about how child stars develop. Using the ALMA radio telescope in Chile, the team discovered that the protostellar disk surrounding the baby star was emitting clouds of dust, gas and electromagnetic energy in its embryonic state.

These “sneezes,” as the researchers describe them, release magnetic flux inside the protostellar disk and may be an important part of star formation. Their findings were published at: Astrophysical Journal.

All stars, including our Sun, consist of large concentrations of gas and dust, called stellar nurseries, which then condense to form the stellar core, the baby star. During this process, gas and dust form a ring around the child star, called the protostellar disk.

“These structures are constantly penetrated by a magnetic field, which brings with it magnetic flux. However, if all this magnetic flux had continued during the evolution of the star, it would have produced magnetic fields much stronger than those observed in any known protostar.” explains Kazuki Tokuda of Kyushu University’s Faculty of Science and first author of the study.

Therefore, researchers hypothesized that a mechanism existed to eliminate this magnetic flux during the star’s evolution. The prevailing view was that the magnetic field gradually weakened over time as the cloud was drawn into the star’s core.

To understand the essence of this mysterious phenomenon, the team targeted MC 27, a stellar nursery located approximately 450 light-years from Earth. The observations were collected using the ALMA array, which consists of 66 high-sensitivity radio telescopes built 5,000 meters above sea level in northern Chile.

“After analyzing our data, we discovered something quite unexpected. There were these ‘spike’ structures extending several astronomical units from the protostellar disk. As we dug deeper, we discovered that these were bursts of ejected magnetic flux, i.e. dust and gas,” Tokuda continues.

“This phenomenon is called ‘exchange instability,’ when the instability of the magnetic field responds to the different density of gases in the protostellar disk, resulting in the magnetic flux being thrown outward. We called it the ‘sneeze’ of the child star because of its similarity when we clear dust and air at high speeds.”

Additionally, other spikes were observed several thousand AU away from the protostellar disk. The team suggested that this pointed to other “sneezes” in the past.

The team expects their discovery to improve our understanding of the complex processes that shape the universe, which continues to interest both the astronomy community and the public.

“Similar pointed structures have been observed in other young stars, and this is becoming an increasingly common astronomical discovery,” Tokuda concludes. “By studying the conditions that lead to these ‘sneezes,’ we hope to expand our understanding of how stars and planets form.”

Kyushu University researchers have shed new light on an important question about how child stars develop. Using the ALMA radio telescope in Chile, the team discovered that the protostellar disk surrounding the baby star was emitting clouds of dust, gas and electromagnetic energy in its embryonic state.