First Magnetic Field Detection on a Class I Protostar

TL;DR

This paper reports the first detection of a strong magnetic field on a Class I protostar, providing new insights into magnetic properties during early stellar evolution and accretion processes.

Contribution

It presents the first measurement of magnetic field strength on a Class I protostar, expanding understanding of magnetic influence in early star formation stages.

Findings

Detected a magnetic field of approximately 2.9 kG on WL 17

Supports the presence of magnetic fields in early protostars

Aligns with magnetospheric accretion models for young stars

Abstract

Strong stellar magnetic fields are believed to truncate the inner accretion disks around young stars, redirecting the accreting material to the high latitude regions of the stellar surface. In the past few years, observations of strong stellar fields on T Tauri stars with field strengths in general agreement with the predictions of magnetospheric accretion theory have bolstered this picture. Currently, nothing is known about the magnetic field properties of younger, more embedded Class I young stellar objects (YSOs). It is believed that protostars accrete much of their final mass during the Class I phase, but the physics governing this process remains poorly understood. Here, we use high resolution near infrared spectra obtained with NIRSPEC on Keck and with Phoenix on Gemini South to measure the magnetic field properties of the Class I protostar WL 17. We find clear signatures of a strong stellar magnetic field. Analysis of this data suggests a surface average field strength of $2.9 \pm 0.43$ kG on WL 17. We present our field measurements and discuss how they fit with the general model of magnetospheric accretion in young stars.