Identifying a High-confidence Candidate of Stellar Coronal Mass Ejection on an M~dwarf

Abstract

Although coronal mass ejections (CMEs) potentially play an important role in shaping the habitability of exoplanets, the firm detection of flaring-associated CMEs on remote stars remains a challenge task at current stage. We here report time-resolved spectroscopic follow-up observations of a superflare (GWAC~251130A) on an M-dwarf, triggered by the SVOM/GWAC high-cadence transient survey. With an amplitude of ≈2.5~mag in R−band, the bolometric flaring energy is estimated to be 1.2^+1.0_−0.5×10³⁵~erg. The spectroscopy reveals complex flare-associated plasma motions. A stellar CME candidate on the M-dwarf can be identified on the M~dwarf at high confidence, based on its maximum projected velocity (V_max∼1500 km s⁻¹) measured from the blueshifted broad Hα emission line-the second highest among all reported stellar CME candidates. This velocity makes GWAC~251130A one of the only two events with a Vmax exceeding twice the surface escape velocity. Both chromospheric evaporation and condensation can be additionally identified in the flare after the broad-line emission fades away. The CME mass and corresponding kinetic energy along the line-of-sight are estimated to be ∼3.2×10¹⁹~g and ∼2.1×10³²~erg, respectively, which reinforces the slightly larger expelled mass with depressed kinetic energy in stellar CME than in the solar flare-CME events.

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BibTeX RIS

BibTeX

@misc{wang2026identifying,
  title = {{Identifying a High-confidence Candidate of Stellar Coronal Mass Ejection on an M~dwarf}},
  author = {J. Wang and J. R. Xu and Y. N. Ma and S. Jin and L. J. Wang and Y. Xu and L. P. Xin and G. W. Li and Y. N. Zhu and H. Yang and X. H. Han and H. L. Li and Z. G. Dai and E. W. Liang and X. Y. Wang and C. Wu and J. Y. Wei},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.41452},
  eprint = {2610.41452},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.41452},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Identifying a High-confidence Candidate of Stellar Coronal Mass Ejection on an M~dwarf
AU  - J. Wang
AU  - J. R. Xu
AU  - Y. N. Ma
AU  - S. Jin
AU  - L. J. Wang
AU  - Y. Xu
AU  - L. P. Xin
AU  - G. W. Li
AU  - Y. N. Zhu
AU  - H. Yang
AU  - X. H. Han
AU  - H. L. Li
AU  - Z. G. Dai
AU  - E. W. Liang
AU  - X. Y. Wang
AU  - C. Wu
AU  - J. Y. Wei
PY  - 2026
DA  - 2026/10/30
PB  - arXiv
DO  - 10.48550/arxiv.2610.41452
UR  - https://arxiv.org/abs/2610.41452
AB  - Although coronal mass ejections (CMEs) potentially play an important role in shaping the habitability of exoplanets, the firm detection of flaring-associated CMEs on remote stars remains a challenge task at current stage. We here report time-resolved spectroscopic follow-up observations of a superflare (GWAC~251130A) on an M-dwarf, triggered by the SVOM/GWAC high-cadence transient survey. With an amplitude of ≈2.5~mag in R−band, the bolometric flaring energy is estimated to be 1.2^+1.0_−0.5×10^35~erg. The spectroscopy reveals complex flare-associated plasma motions. A stellar CME candidate on the M-dwarf can be identified on the M~dwarf at high confidence, based on its maximum projected velocity (V_max∼1500 km s^−1) measured from the blueshifted broad Hα emission line-the second highest among all reported stellar CME candidates. This velocity makes GWAC~251130A one of the only two events with a V_max exceeding twice the surface escape velocity. Both chromospheric evaporation and condensation can be additionally identified in the flare after the broad-line emission fades away. The CME mass and corresponding kinetic energy along the line-of-sight are estimated to be ∼3.2×10^19~g and ∼2.1×10^32~erg, respectively, which reinforces the slightly larger expelled mass with depressed kinetic energy in stellar CME than in the solar flare-CME events.
ER  -

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