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Title: Ground-based detection of G star superflares with NGTS
Authors: Jackman, James A G
Wheatley, Peter J
Pugh, Chloe E
Gänsicke, Boris T
Gillen, Edward
Broomhall, Anne-Marie
Armstrong, David J.
Burleigh, Matthew R.
Chaushev, Alexander
Eigmüller, Philipp
Erikson, Anders
Goad, Michael R.
Grange, Andrew
Günther, Maximilian N.
Jenkins, James S.
McCormac, James
Raynard, Liam
Thompson, Andrew P. G.
Udry, Stéphane
Walker, Simon
Watson, Christopher A.
West, Richard G.
First Published: 10-Apr-2018
Publisher: Oxford University Press (OUP), Royal Astronomical Society
Citation: Monthly Notices of the Royal Astronomical Society, 2018, 477(4), pp. 4655–4664.
Abstract: We present high cadence detections of two superflares from a bright G8 star (V = 11.56) with the Next Generation Transit Survey (NGTS). We improve upon previous superflare detections by resolving the flare rise and peak, allowing us to fit a solar flare inspired model without the need for arbitrary break points between rise and decay. Our data also enables us to identify substructure in the flares. From changing star-spot modulation in the NGTS data, we detect a stellar rotation period of 59 h, along with evidence for differential rotation. We combine this rotation period with the observed ROSAT X-ray flux to determine that the star’s X-ray activity is saturated. We calculate the flare bolometric energies as 5.4+0.8 −0.7 × 10^34 and 2.6+0.4 −0.3 × 10^34 erg and compare our detections with G star superflares detected in the Kepler survey. We find our main flare to be one of the largest amplitude superflares detected from a bright G star. With energies more than 100 times greater than the Carrington event, our flare detections demonstrate the role that ground-based instruments such as NGTS can have in assessing the habitability of Earth-like exoplanets, particularly in the era of PLATO.
DOI Link: 10.1093/mnras/sty897
ISSN: 0035-8711
eISSN: 1365-2966
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2018, Oxford University Press (OUP), Royal Astronomical Society. Deposited with reference to the publisher’s open access archiving policy. (
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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