A Possible Stellar CME Event Associated with a Long-duration Optical Flare on the RS CVn-type Star UX Arietis

2026/08/04 by Cao Dongtao, Gu Shenghong
Physics and Astronomy · #astro-ph.SR

paper · pdf · doi:10.3847/1538-4357/ae78ca

published as 2026ApJ..1005..187C

arxiv created 2026/08/04 · arxiv updated 2026/08/05

Abstract

Coronal mass ejections (CMEs) are large-scale eruptions of magnetized plasma from stellar coronae, and they are always accompanied by flares. In this study, we present high-resolution spectroscopic observations of a long-duration optical flare on the RS CVn-type star UX Arietis (UX Ari). Around the flare peak, we have detected a far-blueshifted emission component in the Hα line profile---a signature of an erupting prominence---indicating a possible stellar CME. After correcting for projection effects, the eruption velocity reaches ∼ -432 km s^-1 when assuming radial propagation, significantly exceeding the escape velocity of the primary component (≈ 304 km s^-1). This strongly supports the detection of a stellar CME. The mass of this CME is at least 2.7 × 10²⁰ g, and its kinetic energy is 2.5 × 10³⁵ erg. The mass value is consistent with the solar flare--CME scaling relation, while its kinetic energy lies below the solar trend. The flare itself released an energy of 4.2 × 10³⁶ erg in the Hα, corresponding to a white-light bolometric energy of roughly 2.8 × 10³⁸ erg. Throughout the flaring event, evolving asymmetries in the Hα profile reveal complex plasma dynamics.

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