First High Resolution Interferometric Observation of a Solar Prominence With ALMA

TL;DR

This paper reports the first high-resolution interferometric observation of a solar prominence at 84-116 GHz using ALMA, revealing detailed prominence morphology and thermal properties consistent with Hα observations.

Contribution

It provides the first high-resolution ALMA interferometric imaging of a solar prominence at millimeter wavelengths, demonstrating the overlap of emission mechanisms with Hα and estimating optical thickness and temperature.

Findings

Brightness temperature of 6000-7000 K in the prominence spine.

Maximum millimeter-continuum optical thickness estimated at ~2.

Prominence morphology consistent with Hα observations.

Abstract

We present the first observation of a solar prominence at $84-116$ GHz using the high resolution interferometric imaging of ALMA. Simultaneous observations in H$\alpha$ from Bia{\l}kaw Observatory and with SDO/AIA reveal similar prominence morphology to the ALMA observation. The contribution functions of 3 mm and H$\alpha$ emission are shown to have significant overlap across a range of gas pressures. We estimate the maximum millimetre-continuum optical thickness to be $\tau_\mathrm{3mm}\approx 2$, and the brightness temperature from the observed H$\alpha$ intensity. The brightness temperature measured by ALMA is $\sim 6000-7000$ K in the prominence spine, which correlates well with the estimated brightness temperature for a gas temperature of 8000 K.