Mineral fragments preserved in a meteorite suggest that a powerful magnetic field was present from the very first moments of the solar system’s formation. According to a study published in the Proceedings of the National Academy of Sciences , this field, along with gravity, could have helped transport gas toward the young Sun. However, the researchers emphasize that other meteorites will need to be studied to confirm this interpretation.
A magnetic trace in a meteorite
To trace the history back to this period, the team of Cauê Borlina, a planetary scientist at Purdue University, examined a meteorite that fell to Earth in 2008. The researchers focused on five iron-rich mineral inclusions. Electrons in this element can rearrange themselves under the influence of a magnetic field and retain a record of this rearrangement.
Using sensitive magnetometers, the team mead a field of a few gauss within these inclusions, an intensity several times greater than that of Earth’s current magnetic field. These minerals are believed to have solidified more than 4.5 billion years ago, before the formation of the Sun and planets. They thus offer a clue to the conditions that prevailed in the cloud of gas and dust that gave rise to the solar system.
Gravity might not have acted alone
Scientists have long debated the respective roles of gravity and magnetism in the collapse of this cloud and the formation of the Sun. Previous work had suggested that a magnetic field extended across the solar system after the star’s birth. It was more difficult to determine whether this field already existed during the very earliest stages of its formation.
Simulations of planetary system formation indicate that a stronger magnetic field can transport more gas to a nascent star. In the earliest phase, known as « Class 0, » some models estimate that the young Sun could have accumulated more than 300 Earth masses of gas per year. The energy found in inclusions is consistent with a significant contribution of magnetism to this process, according to Borlina. However, it does not, on its own, demonstrate what proportion of the gas was transported in this way.
Results to be confirmed
Indrani Das, a theoretical astrophysicist at the Institute of Astronomy and Astrophysics of the Academia Sinica, believes these results shed valuable light on the early solar system. However, she urges caution: the study is based on five inclusions from a single meteorite. Meaments taken on other meteorites will be necessary to verify whether this magnetic signature is found in other samples.
These observations therefore reinforce the idea that magnetism may have played a role in the birth of the Sun, without ruling out the role of gravity. They provide a direct mea of the intensity of an ancient field, but the implications of this result will need to be clarified by further analyses.
Source: Science News (www.sciencenews.org)
Original article: See the original source
Author: Katherine Kornei
