O estudo dos campos magnéticos revelou que estes são mais fracos do que o esperado. Uma nova proposta sugere que o mecanismo de descarga ‘espirra’ algum do fluxo magnético para o Espaço. Usando o ALMA, a equipa espera compreender as descargas e a forma como estas influenciam a formação estelar.
Numa parte bastante discreta da galáxia, uma estrela formou-se lentamente a partir de uma nuvem de gás e poeira. Este acontecimento teve lugar há cerca de 4,6 mil milhões de anos e, pouco depois, a jovem estrela quente começou a limpar a área circundante de gás e poeira.
O que restou foi um disco que rodeava a estrela, conhecido como disco protoestelar. Eventualmente, formaram-se os planetas do nosso Sistema Solar. No entanto, este fenómeno não é exclusivo do nosso sistema, pois existem discos como este à volta de muitas estrelas. Um exemplo muito conhecido são as estrelas do aglomerado do Trapézio, no interior da Nebulosa de Orion.
A Japanese team from Kyushu University has been examining data from the ALMA radio telescope to find out more about stars in the early stages of development. To their surprise, they discovered that the disks around new stars seem to emit jets or plumes of dust and gas and even electromagnetic energy. The team called them "sneezes" and it is this process that seems to slowly erode the magnetic flux of a young star system.
One of the phenomena of the disks is a powerful magnetic field that permeates the entire region. It therefore carries a magnetic flux and this is where the problem lies. The magnetic fields would be much stronger than those observed if the magnetic flux had been maintained from day one. History shows us that they apparently didn't, so the flux was slowly eroded in new star and planetary systems.
One such proposal was that the field slowly diminished as the surrounding dust cloud collapsed into the star's core. To explore the phenomenon, the team studied MC 27, a system 450 light-years away, using ALMA, the Atacama Large Millimetre Array. In total, 66 radio telescopes pointed at the object at an altitude of 5000 meters. They discovered that there were spike-like structures that appeared to extend for a few astronomical units (the average distance between the Sun and the Earth).
The team discovered that the structures contained gas and dust, but had a magnetic flux. Known as "exchange instability", the field shows instabilities when it reacts with different densities of gas. They referred to these instabilities, not as exchange instability, but as a sneeze from a baby star. Just like a human sneeze that expels dust and gas, or rather air, from our bodies, a young, hot star also 'sneezes' and releases gas and dust from the disk.
Further exploration revealed signs of other plumes several thousand astronomical units away from the protostellar disk. They suggest that this is evidence of other sneezes in the past. However, it's not just MC 27, the spikes have been observed in other star systems, but more time is needed to fully understand the implications of the discovery.
