Kepler Flares III: Stellar Activity on GJ 1245 A and B

Abstract

We present the flare occurrence rates and starspot evolution for GJ 1245 A and B, two active M5 stars, based on nine months of Kepler short cadence observations, and four years of nearly continuous long cadence observations. The A component is separated from the B component by 7 arcseconds, and the stars are not resolved in the Kepler pipeline processing due to Kepler's large plate scale of 4 arcseconds/pixel. Analyzing the target pixel data, we have generated separate light curves for components A and B using the PyKE pixel response function modeling procedures, and note the effects of CCD saturation and non-linear response to high energy flares. In our sample, GJ 1245A and B exhibit an average of 3.0 and 2.6 flares per day, respectively. We introduce a new metric, $L_{fl}/L_{\mathrm{Kp}}$, to compare the flare rates between stars, and discuss this in the context of GJ 1245 A and B. Both stars exhibit starspot features that evolve on long time scales, with the slower rotating B component showing evidence of differential rotation. Intriguingly, the angular separation between the A and B component photocenters decreases during the four years of observations in a manner consistent with a shift in the position of the A photocenter due to the orbit of its unseen M8 companion (GJ 1245C), which is $\sim$94% less bright. Among the most detailed photometric studies of fully convective M dwarfs in a multiple system, these results provide an important constraint on stellar age-rotation-activity models.

15 pages, 10 figures, 2 tables. Accepted to ApJ

References in corpus (6)

• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• Large-scale magnetic topologies of late M dwarfs
• Kepler Flares I. Active and Inactive M dwarfs
• Simulations of dynamo action in fully convective stars
• Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243
• Magnetic field generation in fully convective rotating spheres

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• Flare Rates, Rotation Periods. and Spectroscopic Activity Indicators of a Volume-Complete Sample of Mid-to-Late M dwarfs within 15 Parsecs
• Stellar flares observed in long cadence data from the Kepler mission
• Flares in Open Clusters with K2. I. M45 (Pleiades), M44 (Praesepe) and M67
• 10 Years of Stellar Activity for GJ 1243
• Rotating Stars from Kepler Observed with Gaia DR1
• Kepler Flares IV: A Comprehensive Analysis of the Activity of the dM4e Star GJ 1243
• Persistent starspot signals on M dwarfs: multi-wavelength Doppler observations with the Habitable-zone Planet Finder and Keck/HIRES
• LAMOST Observations of Flaring M Dwarfs in the Kepler Field
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• Flares hunting in hot subdwarf and white dwarf stars from Cycles 1-5 of TESS photometry
• LO Peg: surface differential rotation, flares, and spot-topographic evolution
• The view from K2: Questioning the traditional view of flaring on early dM stars
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• Kepler data on KIC 7341653, a nearby M dwarf with monster flares and a phase-coherent variability