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SUMMARY:A deep radius valley revealed by Kepler short cadence observations
  - Cynthia Ho (UCL)
DTSTART:20221115T130000Z
DTEND:20221115T140000Z
UID:TALK192668@talks.cam.ac.uk
CONTACT:Dr Emily Sandford
DESCRIPTION:The characteristics of the radius valley\, i.e.\, an observed 
 lack of planets between 1.5-2 Earth radii at periods shorter than about 10
 0 days\, provide insights into the formation and evolution of close-in pla
 nets. In this talk\, I present a novel view of the radius valley by refitt
 ing the transits of over 400 planets using Kepler 1-minute short cadence o
 bservations\, the vast majority of which have not been previously analysed
  in this way. In some cases\, the updated planetary parameters differ sign
 ificantly from previous studies\, resulting in a deeper radius valley than
  previously observed. This suggests that planets are likely to have a more
  homogeneous core composition at formation. Furthermore\, using support-ve
 ctor machines\, I show that the radius valley location depends on orbital 
 period\, stellar mass\, and stellar age. These findings favour thermally-d
 riven mass loss models such as photoevaporation and core-powered mass loss
 \, with a slight preference for the latter scenario. Finally\, I will high
 light the value of transit observations with short photometric cadence to 
 precisely determine planet radii.
LOCATION:Ryle seminar room + ONLINE - Details to be sent by email
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