Electron Cyclotron Maser Emission from Ejected Stellar Prominences on V374 Peg

TL;DR

This paper investigates whether bursty radio emissions from the active M dwarf V374 Peg can arise from electron cyclotron maser (ECM) emission powered by ejected stellar prominences. Using a data-driven PFSS-based magnetic field model anchored to a ZDI map, the authors synthesize ECM signatures by simulating prominence ejections along coronal field lines and constructing dynamic spectra across rotation and frequency. They find that the energy from prominence ejections can drive ECM emission at the observed frequencies, with phase-dependent visibility and fluxes that align with four Hallinan bursts, especially when higher harmonics contribute. The work demonstrates prominence-ejection–driven ECM as a viable mechanism for V374 Peg’s radio bursts and provides predictions for dissipation timescales, harmonic contributions, and the need for complementary emission components to explain the quiescent baseline, guiding future observational campaigns.

Abstract

We investigate a possible origin for bursty radio emission observed on the active M dwarf V374 Peg, combining data-driven magnetic field modelling with archival radio light curves. We examine whether stellar prominence ejection can plausibly account for the observed radio bursts that have been attributed to electron cyclotron maser (ECM) emission. Our analysis shows that ejected prominences can produce the required energy range to drive the emission, and that modelled ECM visibility exhibits a rotational phase dependence consistent with the limited observational data (four observed bursts). The results support prominence ejection as a viable mechanism for ECM generation on V374 Peg and motivate further observational campaigns to constrain this process.

Figures (15)

• Figure 1: Diagram illustrating how the ejection of a prominence at or beyond the co-rotation radius can power ECM emission. Left: Mass flows up the field lines into the prominence. Middle: The prominence becomes too massive for the magnetic field to support and begins to pull away, deforming the magnetic field lines as it does so. Right: The prominence is ejected, causing a sudden reorganization of the magnetic field. This forces a beam of electrons down the magnetic flux tube, and induces ECM emission.
• Figure 2: Diagram illustrating ECM emission directionality. The parts of the flux tube where conditions allow ECM emission are those closest to the star. The photons are emitted perpendicular to the flux tube in a hollow cone with an opening angle of $90\degree$ and width $\sigma$ (see inset on right).
• Figure 3: The radial component of the ZDI-determined surface magnetic field map for V374 Peg from August 2005 Donati_2006Sci...311..633D.
• Figure 4: Prominence lifetime ($\tau$) and plasma $\beta$ contours in coronal temperature ($T_{cor}$) vs pressure scaling factor ($\kappa_p$) space. $\tau$ is measured in days. The shaded region satisfies the criteria $\beta \le 1$ and $\tau \le 0.38$ days. The dotted lines mark $T_{cor} = 6\times10^6$ K and $\kappa_p = 10^{-6.5}$.
• Figure 5: Free-free flux vs. source surface radius ($R_{ss}$) for V374 Peg. Frequencies that correspond to the centres of the VLA S-, C-, and X-bands, as well as the observing frequency used by Hallinan_2009AIPC.1094..146H are calculated using the methods outlined in Brasseur_2024MNRAS.530.2442B. The flux we fit the model to (0.75 mJy) is marked.