They catch the formation of a massive star with magnetic fields

Jan. 13 () –

observations of a rare event in astronomy have revealed the magnetic processes that allow a massive star to form.

The stellar nursery where the action takes place, called BYF 73, is not your typical star-forming cloud. It is relatively small, but at its central core is a young star that holds the record for the highest known rate of accumulation of protostellar mass, the process by which a growing star accumulates mass from the material around it.

Using the now retired SOFIA airborne telescope and another observatory, the Atacama Large Millimeter/submillimeter Array (ALMA) In Chile, Peter Barnes, a research scientist at the Institute for Space Sciences in Boulder, Colorado, and his team examined the magnetic fields within this cloud amid ongoing star formation.

Studying the orientation of magnetic fields may shed light on their role in the formation of massive stars, a long-standing issue. Massive stars form through a different process than their more average counterparts, relying on a continuous exchange of material with their surroundings, instead of accumulating mass from a disk of surrounding matter.

A ‘MASKED MONSTER’

Previous ALMA research had shown that within the core of BYF 73 lies a “masked monster”: a single protostar, MIR 2, which is about 1,300 times the mass of the Sun and is responsible for about half of the energy output of the region. These ALMA values ​​place MIR 2 in the early stages of massive star formation, with an age of about 40,000 years; on human time scales, it began to form sometime after the arrival of humans in Australia.

“It’s exciting because MIR 2 appears to be very young, and massive stars evolve very quickly by astronomical standards and are very rare, making their early stages easy to miss,” Barnes said. it’s a statement.

The SOFIA and ALMA data offer high resolution and sensitivity in their respective wavelength ranges, allowing Barnes and his team to map the polarization of dust grains in BYF 73. This helped the researchers determine the relationship between the magnetic field of the cloud and the density of the gas, and what that could mean for the formation of MIR 2.

The researchers found that both the magnetic field strength and the gas density are at the upper end of the typical range for star-forming clouds, but the relationship between the two scales is as expected. This means that what is happening in BYF 73 is not necessarily something unique, it is simply massive, and its density is monstrous in comparison to its small size. it may help astronomers discover a threshold needed for gravity to take over and allow stars to form.

Gravity is the only force responsible for star formation, but the unusually strong magnetic field in BYF 73 could be acting in opposition, preventing lower-mass stars from forming. until gravity is strong enough to form a monster.

“The original discovery of the mass input of material [en MIR 2] This was very exciting, as very few examples of higher-mass protostars were known. From that point on, BYF has been the gift that keeps on giving,” Barnes said.

MIR 2 is still in the early stages of massive star formation, and synergies between SOFIA’s and ALMA’s magnetic field studies have helped to clarify the factors involved in the process. “Without their discoveries, BYF 73 and the MIR 2 inside it would still be a real challenge,” Barnes said.

SOFIA was a joint project of NASA and the German Space Agency (DLR).