A Superflare on YZ Canis Minoris Observed by Seimei Telescope and TESS: Red Asymmetry of H$\alpha$ Emission Associated with White-Light Emission

Abstract

Active M-type stars are known to often produce superflares on the surface. Radiation from stellar (super-)flares is important for the exoplanet habitability, but the mechanisms are not well understood. In this paper, we report simultaneous optical spectroscopic and photometric observations of a stellar superflare on an active M dwarf YZ CMi with the 3.8-m Seimei telescope and the $TransitingExoplanetSurveySatellite$. The flare bolometric energy was $1.3_{-0.6}^{+1.6}\times 10^{34}\mathrm{erg}$ and H$\alpha$ energy was $3.0_{-0.1}^{+0.1}\times 10^{32}\mathrm{erg}$. The H$\alpha$ emission line profile showed red asymmetry throughout the flare with a duration of $4.6-5.1\mathrm{hrs}$. The velocity of the red asymmetry was $\sim 200-500\mathrm{km}{\mathrm{s}}^{-1}$ and line width of H$\alpha$ was broadened up to $34\pm 14$ $\mathring{A}$. The redshifted velocity and line width of H$\alpha$ line decayed more rapidly than the equivalent width, and their time evolutions are correlated with that of the white-light emission. This indicates a possibility that the white light, H$\alpha$ red asymmetry, and H$\alpha$ line broadening originate from nearly the same site, i.e., the dense chromospheric condensation region heated by non-thermal electrons. On the other hand, the flux ratio of the redshifted excess components to the central components is enhanced one hour after the flare onset. This may be due to the change of the main source of the red asymmetry to the post-flare loops in the later phase of the flare.

13 pages, 5 figures. Accepted for publication in The Astrophysical Journal

References in corpus (29)

• The Transiting Exoplanet Survey Satellite
• Kepler Flares I. Active and Inactive M dwarfs
• The Kepler Catalog of Stellar Flares
• Do Kepler superflare stars really include slowly-rotating Sun-like stars ? - Results using APO 3.5m telescope spectroscopic observations and Gaia-DR2 data -
• A White Light Megaflare on the dM4.5e Star YZ CMi
• Probable detection of an eruptive filament from a superflare on a solar-type star
• M Dwarfs in SDSS Stripe 82: Photometric Light Curves and Flare Rate Analysis
• Radiative Hydrodynamic Models of Optical and Ultraviolet Emission from M Dwarf Flares
• M Dwarf Metallicities and Giant Planet Occurrence: Ironing Out Uncertainties and Systematics
• The quest for stellar coronal mass ejections in late-type stars: I. Investigating Balmer-line asymmetries of single stars in Virtual Observatory data
• Statistical Properties of Superflares on Solar-type Stars: Results Using All of the Kepler Primary Mission Data
• Superflare occurrence and energies on G-, K- and M-type dwarfs
• The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares I: Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29
• New Insights into White-Light Flare Emission from Radiative-Hydrodynamic Modeling of a Chromospheric Condensation
• An empirical calibration to estimate cool dwarf fundamental parameters from H-band spectra
• Time-resolved spectroscopy and photometry of an M dwarf flare star YZ Canis Minoris with OISTER and TESS: Blue asymmetry in H$\alpha$ line during the non-white light flare
• EvryFlare III: Temperature Evolution and Habitability Impacts of Dozens of Superflares Observed Simultaneously by Evryscope and TESS
• Hydrogen Balmer Line Broadening in Solar and Stellar Flares
• Optical and X-ray observations of stellar flares on an active M dwarf AD Leonis with Seimei Telescope, SCAT, NICER and OISTER
• Sun-as-a-star Analyses of Various Solar Active Events Using H$\alpha$ Spectral Images Taken by SMART/SDDI
• A simple model of chromospheric evaporation and condensation driven conductively in a solar flare
• Search for flares and associated CMEs on late-type main-sequence stars in optical SDSS spectra
• Thermal instabilities: Fragmentation and field misalignment of filament fine structure
• Discovery of a Long-Duration Superflare on a Young Solar-Type Star EK Draconis with Nearly Similar Time Evolution for H$\alpha$ and White-Light Emissions
• The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. II. Hydrogen Broadening Predictions for Solar Flare Observations with the Daniel K. Inouye Solar Telescope
• Sun-as-a-star Analysis of H$\alpha$ Spectra of a Solar Flare Observed by SMART/SDDI: Time Evolution of Red Asymmetry and Line Broadening
• Electron Beams Cannot Directly Produce Coronal Rain
• When hot meets cold: post-flare coronal rain
• Temporal evolution and spatial distribution of white-light flare kernels in a solar flare

Cited by in corpus (12)

• APO & SMARTS flare star campaign observations I. Blue wing asymmetries in chromospheric lines during mid M dwarf flares from simultaneous spectroscopic and photometric observation data
• A comparative study of two X2.2 and X9.3 solar flares observed with HARPS-N: Reconciling Sun-as-a-star spectroscopy and high-spatial resolution solar observations in the context of the solar-stellar connection
• Red Asymmetry of H${}_{\alpha }$ Line Profiles during the flares on the active RS CVn-type star II Pegasi
• Synthesizing Sun-as-a-star flare spectra from high-resolution solar observations
• The CARMENES search for exoplanets around M dwarfs. Behaviour of the Paschen lines during flares and quiescence
• Do Young Suns Produce Frequent, Massive CMEs? Results from Five-year Dedicated Optical Observations of EK Draconis and V889 Hercules
• A Seven-Day Multi-Wavelength Flare Campaign on AU Mic III: Quiescent and Flaring Properties of the X-ray Spectra and Chromospheric lines
• Simulating stellar coronal rain and slingshot prominences
• Flare frequency in M dwarfs belonging to Young Moving Groups
• Doppler-shifted Signatures in the Chromospheric Line Profiles of II Pegasi
• Young M dwarfs flare activity model: Towards better exoplanetary atmospheric characterisation
• Investigating Possible Stellar Coronal Mass Ejections in M-type Dwarfs Using the CARMENES DR1 Spectra