Observationally derived magnetic field strength and 3D components in the HD 142527 disk

Abstract

In protoplanetary disks around young stars, magnetic fields play an important role for disk evolution and planet formation. Polarized thermal emission from magnetically aligned grains is one of the reliable methods to trace magnetic fields. However, it has been difficult to observe magnetic fields from dust polarization in protoplanetary disks because other polarization mechanisms involving grown dust grains become efficient. Here, we report multi-wavelength (0.87 mm, 1.3 mm, 2.1 mm, and 2.7 mm) observations of polarized thermal emission in the protoplanetary disk around HD 142527, showing the lopsided dust distribution. We revealed that the smaller dust still exhibits magnetic alignment in the southern part of the disk. Furthermore, angular offsets between the observed magnetic field and the disk azimuthal direction were discovered, which can be used as a method to measure the relative strengths of each component (radial ($B_r$), azimuthal ($B_{\varphi }$), and vertical ($B_z$)) of 3D magnetic field. Applying this method, we derived the magnetic field around a 200-au radius from the protostar as $|B_r|:|B_{\varphi }|:|B_z|\sim 0.26:1:0.23$ and a strength of $\sim 0.3$ milli-Gauss. Our observations provide some key parameters of magnetic activities including the plasma beta, which have only been assumed in theoretical studies. In addition, the radial and vertical angular momentum transfer are found to be comparable, which poses a challenge to theoretical studies of protoplanetary disks.

Published in Nature Astronomy (2025) as open access, includes supplementary material

References in corpus (18)

• Particle Stirring in Turbulent Gas Disks: Including Orbital Oscillations
• Radiative torques: Analytical Model and Basic Properties
• Magnetic fields in protoplanetary disks
• Placing Confidence Limits on Polarization Measurements
• Hall-effect Controlled Gas Dynamics in Protoplanetary Disks: II. Full 3D Simulations toward the Outer Disk
• Global Simulations of the Inner Regions of Protoplanetary Disks with Comprehensive Disk Microphysics
• Submillimeter polarization observation of the protoplanetary disk around HD 142527
• Grain Alignment and Polarized Emission from Magnetized T Tauri Disks
• Stringent limits on the magnetic field strength in the disc of TW Hya: ALMA observations of CN polarisation
• Global evolution of the magnetic field in a thin disc and its consequences for protoplanetary systems
• Analytical Formulas of Molecular Ion Abundances and N2H+ Ring in Protoplanetary Disks
• On the mass accretion rate and infrared excess in Herbig Ae/Be Stars
• Magnetic fields in protoplanetary disks: from MHD simulations to ALMA observations
• Stellar parameters and accretion rate of the transition disk star HD 142527 from X-Shooter
• Millimeter-wave polarization due to grain alignment by the gas flow in protoplanetary disks
• Polarized emission by aligned grains in the Mie regime : application to protoplanetary disks observed by ALMA
• Low Level Carbon Monoxide Line Polarization in two Protoplanetary Disks: HD 142527 and IM Lup
• Co-evolution of dust grains and protoplanetary disks II: structure and evolution of protoplanetary disks; an analytical approach