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SUMMARY:Reassessing the Evidence for Time Variability in the Atmosphere of
  the Exoplanet HAT-P-7b - Maura Lally (Cornell)
DTSTART:20240305T130000Z
DTEND:20240305T140000Z
UID:TALK210832@talks.cam.ac.uk
CONTACT:Dr Emily Sandford
DESCRIPTION:We reassess the claimed detection of variability in the atmosp
 here of the hot Jupiter HAT-P-7 b\, reported by Armstrong et al. (2016). A
 lthough astronomers expect hot Jupiters to have changing atmospheres\, var
 iability is challenging to detect. We looked for time variation in the pha
 se curves of HAT-P-7 b in Kepler data using similar methods to Armstrong e
 t al. (2016)\, and identified apparently significant variations similar to
  what they found. Numerous tests show the variations to be mostly robust t
 o different analysis strategies. However\, when we injected unchanging pha
 se curve signals into the light curves of other stars and searched for var
 iability\, we often saw similar levels of variations as in the HAT-P-7 lig
 ht curve. Fourier analysis of the HAT-P-7 light curve revealed background 
 red noise from stellar supergranulation on timescales similar to the plane
 t's orbital period. Tests of simulated light curves with the same level of
  noise as HAT-P-7's supergranulation show that this effect alone can cause
  the amplitude and phase offset variability we detect for HAT-P-7 b. There
 fore\, the apparent variations in HAT-P-7 b's atmosphere could instead be 
 caused by non-planetary sources\, most likely photometric variability due 
 to supergranulation on the host star.
LOCATION:Ryle seminar room + ONLINE - Details to be sent by email
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