Detection of Flare-associated CME Candidates on Two M-dwarfs by GWAC and Fast, Time-resolved Spectroscopic Follow-ups

Abstract

The flare-associated stellar coronal mass ejection (CME) in solar-like and late type stars is quite essential for the habitability of an exoplanet. In this paper, we report detection of flare-associated CMEs in two M-dwarfs, thanks to the high cadence survey carried out by the Ground Wide-angle Camera system and the fast photometric and spectroscopic follow-ups. The flare energy in $R-$band is determined to be $1.6\times 10^{35}\mathrm{erg}$ and $8.1\times 10^{33}\mathrm{erg}$ based on the modeling of their light curves. The time-resolved spectroscopyic observations start at about 20 and 40 minutes after the trigger in both cases. The large projected maximum velocity of $\sim 500-700\mathrm{km}{\mathrm{s}}^{-1}$ suggests that the high velocity wing of their H$\alpha$ emission lines are most likely resulted from a CME event in both stars, after excluding the possibility of chromospheric evaporation and coronal rain. The masses of the CMEs are estimated to be $1.5-4.5\times 10^{19}\mathrm{g}$ and $7.1\times 10^{18}\mathrm{g}$.

15 pages, 10 figures and 5 tables, accepted by ApJ

References in corpus (18)

• Painting a portrait of the Galactic disc with its stellar clusters
• Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243
• The Stellar CME-flare relation: What do historic observations reveal?
• Strong dipole magnetic fields in fast rotating fully convective stars
• A stellar flare-coronal mass ejection event revealed by X-ray plasma motions
• The quest for stellar coronal mass ejections in late-type stars: I. Investigating Balmer-line asymmetries of single stars in Virtual Observatory data
• MOST Observations of our Nearest Neighbor: Flares on Proxima Centauri
• Stellar flares observed in long cadence data from the Kepler mission
• A search for flares and mass ejections on young late-type stars in the open cluster Blanco-1
• Spatial Relationship between Solar Flares and Coronal Mass Ejections
• Flares in Open Clusters with K2. I. M45 (Pleiades), M44 (Praesepe) and M67
• The Influence of Coronal Mass Ejections on the Mass-loss Rates of Hot-Jupiters
• A Monster CME Obscuring A Demon Star Flare
• Search for flares and associated CMEs on late-type main-sequence stars in optical SDSS spectra
• Different Signatures of Chromospheric Evaporation in Two Solar Flares Observed with IRIS
• Stellar coronal mass ejections II. Constraints from spectroscopic observations
• An explanation of remarkable emission line profiles in post-flare coronal rain
• A $\Delta R\sim 9.5$ mag Super Flare of An Ultracool Star Detected by $\text{SVOM/GWAC}$ System