Osten, RA;
Kowalski, A;
Drake, SA;
Krimm, H;
Page, K;
Gazeas, K;
Kennea, J;
... Gehrels, N; + view all
(2016)
A Very Bright, Very Hot And Very Long Flaring Event From The M Dwarf Binary System DG CVn.
The Astrophysical Journal
, 832
(2)
, Article 174. 10.3847/0004-637X/832/2/174.
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Abstract
On 2014 April 23, the Swift satellite responded to a hard X-ray transient detected by its Burst Alert Telescope, which turned out to be a stellar flare from a nearby, young M dwarf binary DG CVn. We utilize observations at X-ray, UV, optical, and radio wavelengths to infer the properties of two large flares. The X-ray spectrum of the primary outburst can be described over the 0.3-100 keV bandpass by either a single very high-temperature plasma or a nonthermal thick-target bremsstrahlung model, and we rule out the nonthermal model based on energetic grounds. The temperatures were the highest seen spectroscopically in a stellar flare, at T X of 290 MK. The first event was followed by a comparably energetic event almost a day later. We constrain the photospheric area involved in each of the two flares to be >1020 cm2, and find evidence from flux ratios in the second event of contributions to the white light flare emission in addition to the usual hot, T ∼ 104 K blackbody emission seen in the impulsive phase of flares. The radiated energy in X-rays and white light reveal these events to be the two most energetic X-ray flares observed from an M dwarf, with X-ray radiated energies in the 0.3-10 keV bandpass of 4 1035 and 9 1035 erg, and optical flare energies at E V of 2.8 1034 and 5.2 1034 erg, respectively. The results presented here should be integrated into updated modeling of the astrophysical impact of large stellar flares on close-in exoplanetary atmospheres.
| Type: | Article |
|---|---|
| Title: | A Very Bright, Very Hot And Very Long Flaring Event From The M Dwarf Binary System DG CVn |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/0004-637X/832/2/174 |
| Publisher version: | http://dx.doi.org/10.3847/0004-637X/832/2/174 |
| Language: | English |
| Additional information: | Copyright © 2016 The American Astronomical Society. All rights reserved. |
| Keywords: | stars: coronae; stars: flare; stars: individual (DG CVn) |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/1535281 |
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