Superflare on a rapidly-rotating solar-type star captured in X-rays

Abstract

In this work, we studied X-ray source SRGe~J021932.4$-$040154 (SRGe J021932), which we associated with a single X-ray active star of spectral class G2V-G4V and the rotational period ${\mathrm{P}}_{\mathrm{rot}}<9.3$ days. Additional analysis of TESS light-curves allowed for the rotational period estimation of $3.2\pm 0.5$ days. SRGe J021932 was observed with the SRG/eROSITA during eUDS survey in 2019 in a much dimmer state compared to the XMM-Newton catalogue 4XMM-DR12. Detailed analysis revealed that the archival XMM-Newton observations captured the source during a flaring event in 2017. The XMM-Newton light curve demonstrates a strong flare described with the Gaussian rise and exponential decay, typical for stellar flares, characterized by timescales of $\sim 400$~s and $\sim 1300$~s, respectively. The spectral analysis of the quiescent state reveals $\sim 10$~MK plasma at luminosity of $(1.4\pm 0.4)\times 10^{29}$ erg/s (0.3-4.5 keV). The spectrum of the flare is characterized by temperature of $\sim 40$ MK and luminosity $(5.5\pm 0.6)\times 10^{30}$ erg/s. The total energy emitted during the flare $\sim 1.7\times 10^{34}$ erg exceeds the canonical threshold of $10^{33}$ erg, allowing us to classify the observed event as a superflare on a rapidly-rotating solar-type star. Additionally, we present the upper limit on the surface starspot area based on the brightness variations and consider the hypothesis of the object being a binary system with G-type and M-type stars, suggested by two independent estimations of radial velocity variations from APOGEE-2 and Gaia.

Published in Journal of High Energy Astrophysics

References in corpus (33)

• The Zwicky Transient Facility: System Overview, Performance, and First Results
• Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
• The Revised TESS Input Catalog and Candidate Target List
• The eROSITA X-ray telescope on SRG
• The stellar activity-rotation relationship and the evolution of stellar dynamos
• An Observational Overview of Solar Flares
• X-ray astronomy of stellar coronae (Review)
• The SRG X-ray orbital observatory, its telescopes and first scientific results
• The XMM-Newton serendipitous survey IX. The fourth XMM-Newton serendipitous source catalogue
• Superflares on Ordinary Solar-Type Stars
• Can Superflares Occur on Our Sun?
• EUV Flare Activity in Late-Type Stars
• Statistical properties of superflares on solar-type stars based on 1-min cadence data
• A Kepler Study of Starspot Lifetimes with Respect to Light Curve Amplitude and Spectral Type
• The Mouse that Roared: A Superflare from the dMe Flare Star EV Lac detected by Swift and Konus-Wind
• Nonthermal Hard X-ray Emission and Iron Kalpha Emission from a Superflare on II Pegasi
• The XMM-SERVS survey: new XMM-Newton point-source catalog for the XMM-LSS field
• Relation of X-ray activity and rotation in M dwarfs and predicted time-evolution of the X-ray luminosity
• Starspot activity and superflares on solar-type stars
• A survey of stellar X-ray flares from the XMM-Newton serendipitous source catalogue: Hipparcos-Tycho cool stars
• Lifetimes and Emergence/Decay Rates of Star Spots on Solar-type Stars Estimated by Kepler Data in Comparison with Those of Sunspots
• Superflares, chromospheric activities and photometric variabilities of solar-type stars from the second-year observation of TESS and spectra of LAMOST
• Simultaneous Kepler/K2 and XMM-Netwon observations of superflares in the Pleiades
• A prompt radio transient associated with a gamma-ray superflare from the young M dwarf binary DG CVn
• Stellar Superflares Observed Simultaneously with Kepler and XMM-Newton
• The Great Flare of 2021 November 19 on AD Leo. Simultaneous XMM-Newton and TESS observations
• Investigation of coronal properties of X-ray bright G-dwarf stars based on the solar surface magnetic field -- corona relation
• Swift and XMM-Newton observations of an RS CVn type eclipsing binary SZ Psc: Superflare and coronal properties
• X-Ray Superflares on CC Eri
• Delayed Development of Cool Plasmas in X-ray Flares from kappa1 Ceti
• AstroSat observations of long-duration X-ray superflares on active M-dwarf binary EQ Peg