English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

One critical remaining issue to unclear the initial mass function of thefirst (Population III) stars is the final fate of secondary protostars formedin the accretion disk, specifically whether they merge or survive. We focus onthe magnetic effects on the first star formation under the cosmologicalmagnetic field. We perform a suite of ideal magnetohydrodynamic simulationsuntil 1000 years after the first protostar formation. Instead of the sinkparticle technique, we employ a stiff equation of state approach to representthe magnetic field structure connecting to protostars. Ten years after thefirst protostar formation in the cloud initialized with $B_0 = 10^{-20}$ G at$n_0 = 10^4\,{\rm cm^{-3}}$, the magnetic field strength around protostarsamplifies from pico- to kilo-gauss, which is the same strength as thepresent-day star. The magnetic field rapidly winds up since the gas in thevicinity of the protostar ($\leq\!10$ au) has undergone several tens orbitalrotations in the first decade after protostar formation. As the mass accretionprogresses, the vital magnetic field region extends outward, and the magneticbraking eliminates fragmentation of the disk that would form in theunmagnetized model. On the other hand, assuming a gas cloud with small angularmomentum, this amplification might not work because the rotation would beslower. However, disk fragmentation would not occur in that case. We concludethat the exponential amplification of the cosmological magnetic field strength,about $10^{-18}$ G, eliminates disk fragmentation around the Population IIIprotostars.

Exponentially amplified magnetic field eliminates disk fragmentation around the Population III protostar