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SUMMARY:Linking the formation history of planets with their spectrum - Chr
 istoph Mordasini (University of Bern\, Switzerland)
DTSTART:20150526T130000Z
DTEND:20150526T140000Z
UID:TALK59213@talks.cam.ac.uk
CONTACT:David Titterington
DESCRIPTION:  Despite the enormous increase in observational data on extra
 solar planets in the past two decades\, many aspects of their formation ar
 e still not well understood to date.  In particular\, the formation mechan
 ism of the oldest known class of exoplanets\, the hot Jupiters like 51 Peg
  b\, is still not clear.  A new approach to disentangle different formatio
 n mechanisms might be offered by an observational technique that has recen
 tly seen a lot of progress\, which is the spectroscopy of planetary atmosp
 heres.  This is because the spectrum represent a window into the compositi
 on of a planet.\n   In my talk I will show how it might be possible to fin
 d the traces of the planetary formation history in the spectrum of an exop
 lanet\, based on the results of a planet formation and evolution model and
  assumptions about the refractive and volatile composition of the planetar
 y building blocks.  In particular\, different migration mechanisms (disk m
 igration versus migration due to the Kozai mechanism or planet-planet scat
 tering) might lead to distinct imprints\, which is very important from a p
 lanet formation point of view. To this end we simulate a planet’s format
 ion using a global planet formation model\, tracing the material abundance
 s in the accreted material.  We then consider the planet’s subsequent ev
 olution\, evolving the radius\, internal\, and atmospheric structure to an
  age of several Gyrs when exoplanets are typically observed spectroscopica
 lly.  Using an atmospheric radiative transfer and chemistry model we final
 ly calculate the spectrum of the planets at this age.  With this\, we can 
 study differences in the spectra resulting from\, e.g. different C/O ratio
 s due to different migration histories.  We find that a formation inside t
 he water ice line can lead to a strong imprint\, but only if planetesimals
  in the inner system contain refractory carbon grains in significant quant
 ities.  It is then discussed whether these imprints can be observed with c
 urrent and future instruments like JWST\, and which steps need to be taken
  in the theoretical models to better understand the link between formation
  and spectra.\n
LOCATION:Martin Ryle Seminar Room\, Kavli Institute
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