Statistics of Magnetic Fields for OB Stars

TL;DR

This study analyzes the statistical properties of magnetic fields in OB stars, revealing a power-law distribution and no correlation with rotational velocity, supporting the fossil origin hypothesis.

Contribution

It introduces a statistical analysis of magnetic field distributions in OB stars, highlighting a power-law behavior and the dissipation of weak magnetic fields, which was not previously characterized.

Findings

Magnetic field distribution follows a power-law with an exponent of approximately -1.82.

No correlation between magnetic field strength and rotational velocity.

Weak magnetic fields tend to dissipate rapidly.

Abstract

Based on an analysis of the catalog of magnetic fields, we have investigated the statistical properties of the mean magnetic fields for OB stars. We show that the mean effective magnetic field ${\cal B}$ of a star can be used as a statistically significant characteristic of its magnetic field. No correlation has been found between the mean magnetic field strength ${\cal B}$ and projected rotational velocity of OB stars, which is consistent with the hypothesis about a fossil origin of the magnetic field. We have constructed the magnetic field distribution function for B stars, $F({\cal B})$, that has a power-law dependence on ${\cal B}$ with an exponent of $\approx -1.82$. We have found a sharp decrease in the function $F({\cal B})$F for ${\cal B}\lem 400 G$ that may be related to rapid dissipation of weak stellar surface magnetic fields.