Terahertz photometer to observe solar flares in continuum

TL;DR

This paper introduces a new terahertz photometer system designed for solar flare observations, capable of detecting small temperature variations at THz frequencies, aiding the understanding of flare mechanisms.

Contribution

Development of a novel THz photometer system with high sensitivity for solar flare detection, suitable for balloon or satellite deployment.

Findings

Prototype demonstrates detection of temperature variations smaller than 1 K.

System can detect small solar burst intensities at THz frequencies.

Design enables observations of the entire solar disk with localized flare detection.

Abstract

Solar observations at sub-THz frequencies detected a new flare spectral component peaking in the THz range, simultaneously with the well known microwaves component, bringing challenging constraints for interpretation. Higher THz frequencies observations are needed to understand the nature of the mechanisms occurring in flares. A THz photometer system was developed to observe outside the terrestrial atmosphere on stratospheric balloons or satellites, or at exceptionally transparent ground stations. The telescope was designed to observe the whole solar disk detecting small relative changes in input temperature caused by flares at localized positions. A Golay cell detector is preceded by low-pass filters to suppress visible and near IR radiation, a band-pass filter, and a chopper. A prototype was assembled to demonstrate the new concept and the system performance. It can detect temperature variations smaller than 1 K for data sampled at a rate of 10/second, smoothed for intervals larger than 4 seconds. For a 76 mm aperture, this corresponds to small solar burst intensities at THz frequencies. A system with 3 and 7 THz photometers is being built for solar flare observations on board of stratospheric balloon missions.