Spectral Characteristics of a Rotating Solar Prominence in Multiple Wavelengths

TL;DR

This study uses synthetic spectra from a 2.5D MHD simulation to analyze the spectral signatures of a rotating solar prominence across multiple wavelengths, revealing detectable rotation in some lines but not others.

Contribution

It introduces a novel simulation and spectral synthesis approach to investigate prominence rotation signatures across various spectral lines.

Findings

Distinct rotational signatures in Mg II k, Ly α, and Ly β lines.

Weak or undetectable rotation signals in Ca II 8542 Å, Hα, and Ca II K lines.

Reignites debate on the persistence of rotation in solar prominences.

Abstract

We present synthetic spectra corresponding to a 2.5D magnetohydrodynamical simulation of a rotating prominence in the Ca II 8542 \r{A}, H$\alpha$, Ca II K, Mg II k, Ly $\alpha$, and Ly $\beta$ lines. The prominence rotation resulted from angular momentum conservation within a flux rope where asymmetric heating imposed a net rotation prior to the thermal-instability driven condensation phase. The spectra were created using a library built on the Lightweaver framework called Promweaver, which provides boundary conditions for incorporating the limb-darkened irradiation of the solar disk on isolated structures such as prominences. Our spectra show distinctive rotational signatures for the Mg II k, Ly $\alpha$, and Ly $\beta$ lines, even in the presence of complex, turbulent solar atmospheric conditions. However, these signals are hardly detectable for the Ca II 8542 \r{A}, H$\alpha$, Ca II K spectral lines. Most notably we find only a very faint rotational signal in the H$\alpha$ line, thus reigniting the discussion on the existence of sustained rotation in prominences.