NGTS clusters survey – II. White-light flares from the youngest stars in Orion

Jackman, James A. G.; Wheatley, P. J.; Acton, Jack S.; Anderson, D. R.; Belardi, Claudia; Burleigh, M. R.; Casewell, Sarah L.; Eigmüller, Philipp; Gill, Samuel; Gillen, Edward; Goad, M. R.; Grange, Andrew; Hodgkin, S. T.; Jenkins, James S.; McCormac, J.; Moyano, Maximiliano; Queloz, D.; Raynard, Liam; Tilbrook, Rosanna H.; Watson, Christopher A.; West, R. G.

doi:10.1093/mnras/staa1971

Cited by 20 publications

(19 citation statements)

References 58 publications

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“…All stars from the NGTS fields are shown in cyan, while the flaring stars are depicted with the red circles. The black circles are sources associated with Orion, using the best-fitting SEDs from Jackman et al (2020). The dark grey lines indicate the upper and lower main-sequence limits specified in Section 2.1, and the dashed line is the pre-main-sequence cut-off.…”

Section: Figurementioning

confidence: 99%

“…For each night, we performed a two-step flare detection method. This is the same method as was used by Jackman et al (2018Jackman et al ( , 2019aJackman et al ( , 2020. For clarity, we outline the method here as well.…”

Section: Figurementioning

confidence: 99%

“…Paudel et al 2018), or the energy at which some percentage of flares are recovered (e.g. 68 per cent; Davenport 2016;Jackman et al 2020). This has the advantage of obtaining a sample of flares that are mostly free of detection-sensitivity related effects, but will result in smaller samples due to the rarer nature of higher energy flares.…”

Section: Fitting the Average Flare Occurrence Ratementioning

confidence: 99%

“…These tests were performed on all K and M stars in our sample, whether or not they are on the main sequence. We followed the method outlined by Jackman et al (2020), which itself was based on the flare injection and retrieval method used by Davenport (2016). We injected 50 artificial flares into each night of every K and M star light curve in our sample.…”

Section: Completenessmentioning

confidence: 99%

“…Kounkel et al 2018). This sample of premain-sequence stars was analysed separately in Jackman et al (2020) and underwent Spectral Energy Distribution (SED) fitting to account for the specific extinction and reddening properties from dust in the Orion region. We use the results of this SED fitting for these stars in the rest of this work.…”

Section: Galactic Distributionmentioning

confidence: 99%

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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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Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Fitting the Average Flare Occurrence Ratementioning

confidence: 99%

Section: Completenessmentioning

confidence: 99%

Section: Galactic Distributionmentioning

confidence: 99%

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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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Stellar flares

Kowalski

2024

Living Rev Sol Phys

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Magnetic storms on stars manifest as remarkable, randomly occurring changes of the luminosity over durations that are tiny in comparison to the normal evolution of stars. These stellar flares are bursts of electromagnetic radiation from X-ray to radio wavelengths, and they occur on most stars with outer convection zones. They are analogous to the events on the Sun known as solar flares, which impact our everyday life and modern technological society. Stellar flares, however, can attain much greater energies than those on the Sun. Despite this, we think that these phenomena are rather similar in origin to solar flares, which result from a catastrophic conversion of latent magnetic field energy into atmospheric heating within a region that is relatively small in comparison to normal stellar sizes. We review the last several decades of stellar flare research. We summarize multi-wavelength observational results and the associated thermal and nonthermal processes in flaring stellar atmospheres. Static and hydrodynamic models are reviewed with an emphasis on recent progress in radiation-hydrodynamics and the physical diagnostics in flare spectra. Thanks to their effects on the space weather of exoplanetary systems (and thus in our search for life elsewhere in the universe) and their preponderance in Kepler mission data, white-light stellar flares have re-emerged in the last decade as a widely-impactful area of study within astrophysics. Yet, there is still much we do not understand, both empirically and theoretically, about the spectrum of flare radiation, its origin, and its time evolution. We conclude with several big-picture questions that are fundamental in our pursuit toward a greater understanding of these enigmatic stellar phenomena and, by extension, those on the Sun.

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