Detection of a giant white-light flare on an L2.5 dwarf with the Next Generation Transit Survey

Jackman, James A. G.; Wheatley, P. J.; Burleigh, M. R.; Casewell, Sarah L.; Eigmüller, Philipp; Goad, M. R.; Pollacco, D.; Raynard, Liam; Watson, C. A.; West, R. G.

doi:10.1093/mnrasl/slz039

Cited by 20 publications

(14 citation statements)

References 44 publications

(77 reference statements)

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“…An exceptional example is the recently detected white light flare on an L2.5 cool dwarf star, where a flux increase of 10 magnitudes in the V-band was seen. (Jackman et al 2019a). The calculated flare energy, based on an assumed flare temperature of 9000 K, for that case was 3.4 × 10 33 erg.…”

Section: Other Observations and Habitability Implicationsmentioning

confidence: 99%

Observation of a possible superflare on Proxima Centauri

Kielkopf

Hart

Carter

et al. 2019

Monthly Notices of the Royal Astronomical Society: Letters

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We report the observation on UT 2017.07.01 of an unusually powerful flare detected in near-infrared continuum photometry of Proxima Centauri. During a campaign monitoring the star for possible exoplanet transits, we identified an increase in Sloan i' flux leading to an observed peak at BJD 2457935.996 that was at least 10% over preflare flux in this band. It was followed by a 2-component rapid decline in the first 100 seconds that became a slower exponential decay with time constant of 1350 seconds. A smaller flare event 1300 seconds after the first added an incremental peak flux increase of 1% of pre-flare flux. Since the onset of the flare was not fully time-resolved at a cadence of 62 seconds, its actual peak value is unknown but greater than the time-average over a single exposure of 20 seconds. The i' band is representative of broad optical and near-IR continuum flux over which the integrated energy of the flare is 100 times the stellar luminosity. This meets the criteria that established the concept of superflares on similar stars. The resulting implied ultraviolet flux and space weather could have had an extreme effect on the atmospheres of planets within the star's otherwise-habitable zone.

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Section: Other Observations and Habitability Implicationsmentioning

confidence: 99%

Observation of a possible superflare on Proxima Centauri

Kielkopf

Hart

Carter

et al. 2019

Monthly Notices of the Royal Astronomical Society: Letters

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“…Results to date from searching for stellar flares with NGTS include G star superflares (Jackman et al 2018), the detection of quasiperiodic pulsations from a flare on a pre-main-sequence (pre-MS) M star (Jackman et al 2019a) and the first detection of a white-light flare from an L2.5 dwarf (Jackman et al 2019b). These are single flare events, and it is clear that the wide field of view full-frame images of NGTS can also lend themselves to larger scale studies of flare parameters.…”

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confidence: 99%

Stellar flares detected with the Next Generation Transit Survey

Jackman

Wheatley

Acton

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present the results of a search for stellar flares in the first data release from the Next Generation Transit Survey (NGTS). We have found 610 flares from 339 stars, with spectral types between F8 and M6, the majority of which belong to the Galactic thin disc. We have used the 13 second cadence NGTS lightcurves to measure flare properties such as the flare amplitude, duration and bolometric energy. We have measured the average flare occurrence rates of K and early to mid M stars and present a generalised method to measure these rates while accounting for changing detection sensitivities. We find that field age K and early M stars show similar flare behaviour, while fully convective M stars exhibit increased white-light flaring activity, which we attribute to their increased spin down time. We have also studied the average flare rates of pre-main sequence K and M stars, showing they exhibit increased flare activity relative to their main sequence counterparts.

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“…The 4 -8 GHz flare detected from 2M175-00 would imply coronal plasma densities on the order of n e ∼ 10 11 for plasma emission, which exceed expected densities for active M dwarfs (Villadsen & Hallinan 2019). Recent detections of white-light flares on an L2.5 dwarf (Jackman et al 2019) demonstrate that strong flares persist in early L dwarfs. However, such flares occur less frequently in early L dwarfs compared to M dwarfs (e.g.…”

Section: Dynamic Spectrum Of 2m1750-00mentioning

confidence: 91%

On the Correlation between L Dwarf Optical and Infrared Variability and Radio Aurorae

Richey-Yowell,

Kao,

Pineda

et al. 2020

Preprint

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Photometric variability attributed to cloud phenomena is common in L/T transition brown dwarfs. Recent studies show that such variability may also trace aurorae, suggesting that localized magnetic heating may contribute to observed brown dwarf photometric variability. We assess this potential correlation with a survey of 17 photometrically variable brown dwarfs using the Karl G. Jansky Very Large Array (VLA) at 4 -8 GHz. We detect quiescent and highly circularly polarized flaring emission from one source, 2MASS J17502484-0016151, which we attribute to auroral electron cyclotron maser emission. The detected auroral emission extends throughout the frequency band at ∼5 -25σ, and we do not detect evidence of a cutoff. Our detection confirms that 2MASS J17502484-0016151 hosts a magnetic field strength of ≥2.9 kG, similar to those of other radio-bright ultracool dwarfs. We show that Hα emission continues to be an accurate tracer of auroral activity in brown dwarfs. Supplementing our study with data from the literature, we calculate the occurrence rates of quiescent emission in L dwarfs with low-and high-amplitude variability and conclude that high amplitude O/IR variability does not trace radio magnetic activity in L dwarfs.

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Detection of a giant white-light flare on an L2.5 dwarf with the Next Generation Transit Survey

Cited by 20 publications

References 44 publications

Observation of a possible superflare on Proxima Centauri

Observation of a possible superflare on Proxima Centauri

Stellar flares detected with the Next Generation Transit Survey

On the Correlation between L Dwarf Optical and Infrared Variability and Radio Aurorae

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