Delayed Development of Cool Plasmas in X-Ray Flares from the Young Sun-like Star κ¹ Ceti
dc.contributor.author | Hamaguchi, Kenji | |
dc.contributor.author | Reep, Jeffrey W. | |
dc.contributor.author | Airapetian, Vladimir | |
dc.contributor.author | Toriumi, Shin | |
dc.contributor.author | Gendreau, Keith C. | |
dc.contributor.author | Arzoumanian, Zaven | |
dc.date.accessioned | 2023-03-22T23:10:40Z | |
dc.date.available | 2023-03-22T23:10:40Z | |
dc.date.issued | 2023-02-22 | |
dc.description.abstract | The Neutron star Interior Composition Explorer (NICER) X-ray observatory observed two powerful X-ray flares equivalent to superflares from the nearby young solar-like star κ¹ Ceti in 2019. NICER follows each flare from the onset through the early decay, collecting over 30 counts s⁻¹ near the peak, enabling a detailed spectral variation study of the flare rise. The flare in September varies quickly in ∼800 s, while the flare in December has a few times longer timescale. In both flares, the hard-band (2–4 keV) light curves show typical stellar X-ray flare variations with a rapid rise and slow decay, while the soft X-ray light curves, especially of the September flare, have prolonged flat peaks. The time-resolved spectra require two temperature plasma components at kT ∼0.3–1 and ∼2–4 keV. Both components vary similarly, but the cool component lags by ∼200 s with a four to six times smaller emission measure (EM) compared to the hot component. A comparison with hydrodynamic flare loop simulations indicates that the cool component originates from X-ray plasma near the magnetic loop footpoints that mainly cools via thermal conduction. The time lag represents the travel time of the evaporated gas through the entire flare loop. The cool component has a several times smaller EM than its simulated counterpart, suggesting a suppression of conductive cooling, possibly by the expansion of the loop cross-sectional area or turbulent fluctuations. The cool component’s time lag and EM ratio provide important constraints on the flare loop geometry. | en_US |
dc.description.sponsorship | This material is based upon work supported by NASA under award No. 80GSFC21M0002. J.W.R. was supported by the Office of Naval Research 6.1 Support Program. V.S.A. acknowledges the funds from NICER GO Cycle 2 project award No. 80NSSC21K0101. This work is supported by JSPS KAKENHI grant Nos. JP20KK0072, JP21H01124, and JP21H04492 and NINS grant Nos. 01321802 and 01311904. This research has made use of data and/or software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC. We thank Mr. Craig Gordon for helping resolve a PYXSPEC problem. We thank Dr. Andrew Pollock for suggestions of XMM-Newton RGS data analysis. We thank Drs. Stephen Drake, Ryo Sasaki, Yuta Notsu, Michael F. Corcoran, and Konstantin V. Getman for discussions about stellar flare physics. | en_US |
dc.description.uri | https://iopscience.iop.org/article/10.3847/1538-4357/acae8b | en_US |
dc.format.extent | 15 pages | en_US |
dc.genre | journal articles | en_US |
dc.identifier | doi:10.13016/m2mf6z-bb89 | |
dc.identifier.citation | Hamaguchi, Kenji et al. "Delayed Development of Cool Plasmas in X-Ray Flares from the Young Sun-like Star κ¹ Ceti." The Astrophysical Journal 944, No. 2 (2023 February 22). https://doi.org/10.3847/1538-4357/acae8b. | en_US |
dc.identifier.uri | https://doi.org/10.3847/1538-4357/acae8b | |
dc.identifier.uri | http://hdl.handle.net/11603/27044 | |
dc.language.iso | en_US | en_US |
dc.publisher | IOP | en_US |
dc.relation.isAvailableAt | The University of Maryland, Baltimore County (UMBC) | |
dc.relation.ispartof | UMBC Center for Space Sciences and Technology | |
dc.relation.ispartof | UMBC Faculty Collection | |
dc.relation.ispartof | UMBC Physics Department | |
dc.rights | This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law. | en_US |
dc.rights | Public Domain Mark 1.0 | * |
dc.rights.uri | http://creativecommons.org/publicdomain/mark/1.0/ | * |
dc.title | Delayed Development of Cool Plasmas in X-Ray Flares from the Young Sun-like Star κ¹ Ceti | en_US |
dc.type | Text | en_US |
dcterms.creator | https://orcid.org/0000-0001-7515-2779 | en_US |