Froning, Cynthia S. and Kowalski, Adam and France, Kevin and Loyd, R. O. Parke and Schneider, P. Christian and Youngblood, Allison and Wilson, David and Brown, Alexander and Berta-Thompson, Zachory and Pineda, J. Sebastian and Linsky, Jeffrey and Rugheimer, Sarah and Miguel, Yamila (2019) A Hot Ultraviolet Flare on the M Dwarf Star GJ 674. The Astrophysical Journal, 871 (2). L26. ISSN 2041-8213
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Abstract
As part of the Mega-Measurements of the Ultraviolet Spectral Characteristics of Low-Mass Exoplanetary Systems Hubble Space Telescope (HST) Treasury program, we obtained time-series ultraviolet spectroscopy of the M2.5V star, GJ 674. During the far-ultraviolet (FUV) monitoring observations, the target exhibited several small flares and one large flare (EFUV = 1030.75 erg) that persisted over the entirety of an HST orbit and had an equivalent duration >30,000 s, comparable to the highest relative amplitude event previously recorded in the FUV. The flare spectrum exhibited enhanced line emission from chromospheric, transition region, and coronal transitions and a blue FUV continuum with an unprecedented color temperature of TC ≃ 40,000 ± 10,000 K. In this Letter, we compare the flare FUV continuum emission with parameterizations of radiative hydrodynamic model atmospheres of M star flares. We find that the observed flare continuum can be reproduced using flare models but only with the ad hoc addition of a hot, dense emitting component. This observation demonstrates that flares with hot FUV continuum temperatures and significant extreme-ultraviolet/FUV energy deposition will continue to be of importance to exoplanet atmospheric chemistry and heating, even as the host M dwarfs age beyond their most active evolutionary phases.
Item Type: | Article |
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Subjects: | Euro Archives > Physics and Astronomy |
Depositing User: | Managing Editor |
Date Deposited: | 06 Jun 2023 05:27 |
Last Modified: | 03 Nov 2023 03:46 |
URI: | http://publish7promo.com/id/eprint/2672 |