We present a detailed analysis of a superflare on the active M dwarf star AD Leonis. The event presents a rare case of a stellar flare that was simultaneously observed in X-rays (with XMM-Newton) and in the optical (with the Transiting Exoplanet Survey Satellite, TESS). The radiated energy in the 0.2 - 12 keV X-ray band (1.26 +/- 0.01 x 10(33) erg) and the bolometric value (E-F,E-bol=5.57 +/- 0.03 x 10(33) erg) place this event at the lower end of the superflare class. The exceptional photon statistics deriving from the proximity of AD Leo has enabled measurements in the 1 - 8 angstrom GOES band for the peak flux (X1445 class) and integrated energy (E-F,E-GOES=4.30 +/- 0.05 x 10(32) erg), which enables a direct comparison with data on flares from our Sun. From extrapolations of empirical relations for solar flares, we estimate that a proton flux of at least 10(5)cm(-2)s(-1)sr(-1) accompanied the radiative output. With a time lag of 300 s between the peak of the TESS white-light flare and the GOES band flare peak as well as a clear Neupert effect, this event follows the standard (solar) flare scenario very closely. Time-resolved spectroscopy during the X-ray flare reveals, in addition to the time evolution of plasma temperature and emission measure, a temporary increase in electron density and elemental abundances, and a loop that extends into the corona by 13% of the stellar radius (4 x 10(9) cm). Independent estimates of the footprint area of the flare from TESS and XMM-Newton data suggest a high temperature of the optical flare (25000 K), but we consider it more likely that the optical and X-ray flare areas represent physically distinct regions in the atmosphere of AD Leo.

Stelzer B., Caramazza M., Raetz S., Argiroffi C., Coffaro M. (2022). The Great Flare of 2021 November 19 on AD Leonis: Simultaneous XMM-Newton and TESS observations. ASTRONOMY & ASTROPHYSICS, 667, L9 [10.1051/0004-6361/202244642].

The Great Flare of 2021 November 19 on AD Leonis: Simultaneous XMM-Newton and TESS observations

Argiroffi C.;
2022-11-11

Abstract

We present a detailed analysis of a superflare on the active M dwarf star AD Leonis. The event presents a rare case of a stellar flare that was simultaneously observed in X-rays (with XMM-Newton) and in the optical (with the Transiting Exoplanet Survey Satellite, TESS). The radiated energy in the 0.2 - 12 keV X-ray band (1.26 +/- 0.01 x 10(33) erg) and the bolometric value (E-F,E-bol=5.57 +/- 0.03 x 10(33) erg) place this event at the lower end of the superflare class. The exceptional photon statistics deriving from the proximity of AD Leo has enabled measurements in the 1 - 8 angstrom GOES band for the peak flux (X1445 class) and integrated energy (E-F,E-GOES=4.30 +/- 0.05 x 10(32) erg), which enables a direct comparison with data on flares from our Sun. From extrapolations of empirical relations for solar flares, we estimate that a proton flux of at least 10(5)cm(-2)s(-1)sr(-1) accompanied the radiative output. With a time lag of 300 s between the peak of the TESS white-light flare and the GOES band flare peak as well as a clear Neupert effect, this event follows the standard (solar) flare scenario very closely. Time-resolved spectroscopy during the X-ray flare reveals, in addition to the time evolution of plasma temperature and emission measure, a temporary increase in electron density and elemental abundances, and a loop that extends into the corona by 13% of the stellar radius (4 x 10(9) cm). Independent estimates of the footprint area of the flare from TESS and XMM-Newton data suggest a high temperature of the optical flare (25000 K), but we consider it more likely that the optical and X-ray flare areas represent physically distinct regions in the atmosphere of AD Leo.
11-nov-2022
Settore FIS/05 - Astronomia E Astrofisica
Stelzer B., Caramazza M., Raetz S., Argiroffi C., Coffaro M. (2022). The Great Flare of 2021 November 19 on AD Leonis: Simultaneous XMM-Newton and TESS observations. ASTRONOMY & ASTROPHYSICS, 667, L9 [10.1051/0004-6361/202244642].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/608753
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