China uses advanced solar telescopes to measure magnetic fields with unprecedented accuracy
The Accurate Infrared Magnetic Field Measurements of the Sun (AIMS) are now operational in Lenghu Municipality, Qinghai Province, at an altitude of about 4,000 meters. This solar magnetic field telescope is the first in the world to operate in the mid-infrared wavelength range, marking a significant advance in the direct measurement of the Sun’s magnetic field.
For decades, measurements relied on indirect methods, which limited accuracy. AIMS was developed to address these challenges, moving from traditional 100 gauss accuracy to measurements better than 10 gauss accuracy. Deng Yuanyong of the National Astronomical Observatories of the Chinese Academy of Sciences, who led the project, confirmed: ‘The Sun, the only star we can observe with high precision, has a magnetic field that acts as the energy switch that drives intense solar activities such as solar flares and coronal mass ejections. Yet more than half of the Sun’s total magnetic field manifestations are relatively weak, with strengths of only a few tens of gauss.’
All core components of the telescope are domestically produced, adding to China’s capabilities in astronomical instrument innovation. The telescope uses an off-axis optical system to reduce interference from the high ambient background of the mid-infrared range and integrates cooling and filter technologies to increase the accuracy of magnetic field measurements.
AIMS features an infrared-resolving spectrograph for high-resolution spectral imaging of the solar atmosphere. The team also created a new polarization modulation technique and a polarization aberration-free optical system using five reflective mirrors to minimize instrumental errors. Deng Yuanyong stated, “It is the world’s first solar magnetic field telescope operating in the mid-infrared wavelength range and China’s first astronomical instrument operating in this band.”
The new facility anticipates approximately 250 observation days annually, weather permitting, with data expected to support solar physics research and improve space weather forecasting. International cooperation is a future goal for the project team.
