Seeking echoes of circumstellar disks in Kepler light curves

Abstract

Light echoes of flares on active stars offer the opportunity for direct detection of circumstellar dust. We revisit the problem of identifying faint echoes in post-flare light curves, focusing on debris disks from on-going planet formation. Starting with simulations, we develop an algorithm for estimating the radial extent and total mass from disk echo profiles. We apply this algorithm to light curves from over 2,100 stars observed by NASA's Kepler mission, selected for multiple, short-lived flares in either the long-cadence or short-cadence data sets. While flux uncertainties in light curves from individual stars preclude useful mass limits on circumstellar disks, catalog-averaged light curves yield constraints on disk mass that are comparable to estimates from known debris disks. The average mass in micron- to millimeter-sized dust around the Kepler stars cannot exceed 10% of an Earth mass in exo-Kuiper belts or 10% of a Lunar mass in the terrestrial zone. We group stars according to IR excess, based on WISE W1-W3 color, as an indicator for the presence of circumstellar dust. The mass limits are greater for stars with strong IR excess, a hint that echoes are lurking not far beneath the noise in post-flare light curves. With increased sensitivity, echo detection will let time-domain astronomy complement spectroscopic and direct-imaging studies in mapping how, when, and where planets form.

AJ in press, 35 pages with 14 figures and 2 tables

References in corpus (21)

• The Gaia mission
• The Transiting Exoplanet Survey Satellite
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Debris Disk Evolution Around A Stars
• Kepler Flares I. Active and Inactive M dwarfs
• The Kepler Catalog of Stellar Flares
• A stellar-mass-dependent drop in planet occurrence rates
• Variations on Debris Disks: Icy Planet Formation at 30-150 AU for 1-3 Solar Mass Main Sequence Stars
• Formation and Evolution of Planetary Systems (FEPS): Properties of Debris Dust around Solar-type Stars
• New Debris Disks Around Nearby Main Sequence Stars: Impact on The Direct Detection of Planets
• Collisional processes and size distribution in spatially extended debris discs
• The flare catalog and the flare activity in the Kepler mission
• A Complete ALMA Map of the Fomalhaut Debris Disk
• MOST Observations of our Nearest Neighbor: Flares on Proxima Centauri
• Stellar flares observed in long cadence data from the Kepler mission
• Debris Distribution in HD 95086 - A Young Analog of HR 8799
• The Mass of Stirring Bodies in the AU Mic Debris Disk Inferred from Resolved Vertical Structure
• Stellar chromospheric activity and age relation from open clusters in the LAMOST Survey
• Disk Detective: Discovery of New Circumstellar Disk Candidates through Citizen Science
• Stellar flares from blended and neighbouring stars in Kepler short cadence observations
• Properties of Kepler Stars with the Most Powerful Flares