Improving Precision in Exoplanet Transit Detection Aimée Hall Institute of Astronomy, Cambridge Supervisor: Simon Hodgkin SuperWASP Two observatories: SuperWASP-North (Roque de los Muchachos, La Palma) SuperWASP-South (South African Astronomical Observatory) Wide-Angle Search for Planets: 8 cameras per observatory Each camera has 7.8x7.8 degree field of view 20,000-30,000 stars per field 100 transiting exoplanets discovered Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge SuperWASP β Successful planet hunter 21.5 millimagnitude depth www.superwasp.org Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge SuperWASP β can it get even better? Systematics: A.M.S Smith et al MNRAS. 373 1151 (2006) Noise ~10 mmag Binned: 4-5 mmag White noise limit: 1-2 mmag Post-SYSREM: Noise ~6-7 mmag Binned: 3-4 mmag White noise limit: <2 mmag Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge So many small exoplanets A. W. Howard et al., Ap. J. S. 201 15 (2012) 0.25 RJupiter π πΉ β πΉβπ.ππ 0.5 RJupiter RJupiter Neptunes in the Noise Half the radius = 3.8 times more planets Aimée Hall Institute of Astronomy, Cambridge The ground is the limit? SuperWASP Kepler All known Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge Brighter is better Magnitude distribution of SuperWASP Planets Neptunes in the Noise Pont (2010, www.exoclimes.com) Brighter stars better for atmospheric detection Aimée Hall Institute of Astronomy, Cambridge SuperWASP New Analysis Co-located list driven photometry Soft-edged apertures Robust background estimator Seasonal Flatfields Up to late 2011 After late 2011 Survey Mode 6 minute Cadence Stare Mode 1 minute Cadence Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge SuperWASP Archival Data There is a huge volume of archived SuperWASP data β’ 3.2x1011 data points β’ 30.8 million objects β’ 10.6 million images (V=15) β’ More than half of the observations span at least 4 years (up to 7) β’ Mean of 15,000 epochs per star Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge Noise reduction: Survey mode New analysis Previous analysis Previous analysis + trend removal (SYSREM) 3mmag Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge The colour of noise I - Survey Mode Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge XO-5b Single Transit Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge SuperWASP β Stare Mode 24 nights between Nov-Dec 2011 7 fields in this analysis 6000-14000 raw frames per field 70% of frames have suitable: β’ Average source ellipticity β’ Frame astrometric fit error β’ Seeing β’ Sky level β’ Zero point magnitude Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge The colour of noise II β Stare Mode 2009 Survey Mode 2011 Stare Mode Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge Planet Candidates BLS search for potential transits Selected if: β’ SNR > 6 β’ More than 3 transits observed β’ < 80% of transit data from 1 night 74 candidates have R < 2RJ Smallest candidate radius ~0.6RJ Bold symbols: Includes Nov-Dec 2012 (1 field) Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge Example Candidates Period: 0.31 days Depth ~3.5mmag Neptunes in the Noise Period: 1.68 days Depth ~6 mmag Aimée Hall Institute of Astronomy, Cambridge SuperWASP: Current capabilities Period: 0.31 days Depth ~3.5mmag Neptunes in the Noise Period: 1.68 days Depth ~6 mmag Aimée Hall Institute of Astronomy, Cambridge Future SuperWASP upgraded to stare-mode in late 2011: ~90% of stare mode data left to analyse. Reducing rms noise allows smaller transits (smaller planets) to be detectable Planets half the size are 3-4 times more common For every SuperWASP exoplanet, potential to find 3 new ones! SuperWASP has found more than 30 new planets since 2012β¦ Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge Summary We have developed and tested new processing strategies for SuperWASP: β’ Reach 1mmag noise on stare-mode SuperWASP data on transit duration timescales β’ Improved noise characteristics increase sensitivity to smaller planets and at longer periods β’ Lightcurves can tell blends from true planet candidates, saving follow-up resources With just 44 nights we have 74 candidates with radii between 0.63 RJ and 2RJ Window of opportunity to extend this analysis to the rest of the SuperWASP data to find planets for planet characterisation Neptunes in the Noise Aimée Hall Institute of Astronomy, Cambridge
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