# New evidence for weak magnetic fields in Herbig Ae/Be stars

## TL;DR

This study provides new spectropolarimetric evidence that Herbig Ae/Be stars have weak magnetic fields, with measurements showing fields as low as 17 G, which are weaker than those in T Tauri stars, impacting theories of star and planet formation.

## Contribution

The paper presents the first high-resolution spectropolarimetric measurements of magnetic fields in a sample of Herbig Ae/Be stars, revealing their magnetic fields are significantly weaker than in T Tauri stars.

## Key findings

- Detected magnetic fields as weak as 17 G in Herbig Ae/Be stars.
- Observed polarity changes in some stars indicating complex magnetic structures.
- Confirmed that Herbig Ae/Be stars have weaker magnetic fields than T Tauri stars.

## Abstract

In recent years Herbig Ae/Be stars receive considerable attention as their disks are believed to be the sites of on-going planet formation. Confirming the presence of magnetic fields in these stars is critical for understanding the transport of angular momentum during the protostellar phase. Furthermore, magnetic fields set the conditions for strongly anisotropic accretion. In this study we present the results of our recent observing campaigns of a sample of Herbig Ae/Be stars aimed at measurements of their magnetic fields applying the Singular Value Decomposition method to high resolution spectropolarimetric observations. The strongest longitudinal magnetic field of 209 G is detected in the Herbig Be star HD 58647, whereas the weakest field of 17 G is measured in the Herbig Ae star HD 190073. A change of polarity is detected for HD 58647 and in the Herbig Be star HD 98922. The obtained results provide further evidence that Herbig Ae/Be stars possess much weaker magnetic fields than their lower mass counterpart T Tauri stars with magnetic fields of kG order.