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CATEGORIES:Exoplanet Seminars
SUMMARY:A new exhibit in the planetary zoo: Hot\, rotating
  rocky planets - Simon Lock (Harvard)
DTSTART;TZID=Europe/London:20171005T113000
DTEND;TZID=Europe/London:20171005T123000
UID:TALK87821AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/87821
DESCRIPTION:There is an incredible variation in the mass and r
 adii of exoplanets. Generally\, the properties of 
 exoplanets are inferred from interior structure mo
 dels that treat the bodies as cold\, differentiate
 d and non-rotating. However\, exoplanets are not a
 lways in such states. Models of accretion predict 
 that terrestrial bodies are formed with substantia
 l angular momentum. Rocky bodies can be hot becaus
 e of proximity to their host stars or from giant i
 mpacts during accretion. We present a new code (HE
 RCULES) that solves for the equilibrium structure 
 of rotating bodies as a series of concentric\, con
 stant-density layers. The HERCULES code is an effi
 cient tool for calculating the structure of rotati
 ng exoplanets with realistic equations of state. U
 sing HERCULES and a smoothed particle hydrodynamic
 s (SPH) code\, we show that hot\, rotating bodies 
 display diverse morphologies. In particular\, for 
 rotating bodies there is a thermal limit at which 
 the rotational velocity at the equator intersects 
 the Keplerian orbital velocity. Beyond this corota
 tion limit\, the body forms an extended\, continuo
 us structure with a corotating region and a disk-l
 ike region\, which we have named a synestia. By an
 alyzing SPH calculations of giant impacts and N-bo
 dy models of planet formation\, we show that typic
 al rocky planets reach substantially vaporized sta
 tes multiple times during accretion. For the expec
 ted mean angular momentum of growing planets\, mos
 t of these impact-generated states will exceed the
  corotation limit and be synestias. Hot\, rotating
  structures can have a bulk density several times 
 lower than an equivalent cold\, non-rotating body.
  The density inferred from observations can also b
 e inaccurate by a factor of a few\, depending on t
 he orientation of an oblate body. In addition\, th
 e range of structures for hot\, rotating bodies ha
 s significant implications for the differentiation
 \, cooling and internal dynamics of rocky bodies. 
 Finally\, synestias lead to a new mode of satellit
 e formation that can explain the unique chemical r
 elationship between the Earth and Moon.
LOCATION:Martin Ryle Seminar Room\, Kavli Institute
CONTACT:Ed Gillen
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