ExSSII: Earths, Super-Earths and Habitability

Final session of ExSSII on Earths, Super-Earths and Habitability

liveblogging:

• Dimitar Sasselov - high density exoplanets
  HAT-P-20b - 14 gm/cc - hot 7 M_J giant planet, no prob modeling as degenerate H/He core

  Kepler-10b - 9 gm/cc - rocky
  Earth's central density 13 gm/cc
  Super-Earths expected to have central densities > 20 gm/cc

  update on model progress for moderately high densities, but not degenerate,
  reviewed at Extreme Solar Systems I in Santorini in 2007.

  Experiments at Z-machine - pulsed 10 TW/cm^2 laser compression toy
  zap rocks.

  mmm, toblerone diagram

• Diana Valencia - composition of Super-Earths and Mini-Neptunes
  olivine and pyroxine and perovskite and magnesiowustite, oh my.
  Is magnesiowustite even a real word?

  All iron; iron rich (2/3 iron core); earth-like (1/3 iron core); no iron - all Mg/Si
  get about 50% range in radius at Earth/Super-Earth masses == ~ 2,000 km

  some super-earths clearly Si/Fe, some must be H2O or H/He rich - ie ice subgiants or neptunes

  some on the border - are they pure Mg/Si and no Fe or a mix with thick volatile atmosphere?
  10-20% H2O will do nicely

  compare Si/Fe ratio for parent star - varies by ~ factor of 2

• Drake Deming Fraine giving talke, Drake is here though - multiple transits of GJ1214b with Spitzer

  20d continuous IRAC-2 (4.5 μ) continuous observation of 13 consecutive transits
  analysis in progress

  water world?
  no significant transit timing variations

• Demory - Cnc 55e

  Spitzer photometry of super-earth
  8 earth masses, 0.74 d period - high probability on transit
  seen in transit with MOST and Spitzer

  star is old, slightly sub-solar
  planet is 2(.2) R_E, density of about 5 gm/cc

  new data on 20 June transit

• Marley - when worlds collide

  oligarchic assembly of terrestrials during 30-50Myr later stages of assembly
  expect giant (moon/mars size) impactors
  planet gets hot and glows
  maybe detectable

  cf Zhang et al 2003 for analogous giant planet impact signatures

• Lopez - Kepler-11b

  Water or bit of H/He? Hard to tell

• Dragomir - Transits with MOST

  BD-082823 and 61 Vir
  known RV super-earths with known ephemeris in MOST continuous viewing zone

  since period and phase are known, can zero in on transits, IF they are there

  BD-8... m_V - 10 P=5.6d, m_p(sini) = 13 M_E
  6.7% prior prob of transit
  none seen

  61 Vir - 5th mag, 4d orb per, 7.4% transit prob
  no transit seen

  ---

• Ravi Kapparapu - HZ around low mass stars
  recalculating the habitable zone over wider range of stellar types, especially down to lower stellar masses, with updated atmospheric absorption coefficients and scattering models for greenhouse saturation and rayleigh scattering

  need 3D general circulation models for general insolation, spectra, composition, atmospheric mass and obliquity and rotation periods...

• Steinn Sigurðsson - LHB and outer planet interlopers
  sounds funky, won't be blogging that one...

  Ah, what the heck, sod this modesty thing, read Schilling's tweets at #ESS2...

  Having fun with Planet X - the magic planet that can explain everything, but is Not Nice
  parameters that explain Late Heavy Bombardment for sub-Jovian planets at high inclination

  Rogers - H₂O on Super-Earths
  role of H₂ in atmospheres - extending the habitable zone outer edge by loading up on thick hydrogen molecular atmospheres

  100 atmospheres of molecular hydrogen, or so, will do the trick
  potentially interesting because these are also the atmospheres that will work for rogue planets, per Dave Stevenson

• Elser - Earth-Moon systems

  is a moon important for climate stability (eg obliquity chaos suppression) and hence life?

  oligarchic growth simulations, looking for earth--mars grazing collisions at late times to estimate moon forming events (preprint on arxiv)
  lots of n-body sims

  

  

  pretty pics from press release,
  at least I hope they are pretty, wonder what they look like...

  nice animation, hm there is a press release on this...

  punchline: about 10% +/- of terrestrial planets outhg to have a massive moon, modulo assumptions

  Editorial Comment: eh, maybe - hard to see it being critical for onset of life, might help with long term persistence and/or expediting macro evolution, though the Earth, as is, had it pretty rough for other reasons

• Nader Haghighipour - habitable trojan planets

  looking for earths in HZ orbits around known transiting exoplanet systems
  look for planets in trojan orbits - +/- 60 degrees ahead of or behind a giant planet
  can detect with transit timing variation
  get 100s of sec TTV amplitude for jovians around M stars in HZ orbits and low mass planet in strong resoannces - what about the 1:1 resonance???

  10s of sec for trojans - can be done, needs a bit of luck
  eccentricity helps. as does slightly longer periods

  hm, will laptop battery last to the end of the final session...?
  going to be close!

• Cohen - Extreme Weather

  3D magnetohydrodynamic sims of stellar wind interacting with planetary atmisphere
  looking at short period planets and planet magnetosphere and atmospheric escape
  stellar flares brutal on short orbital period planets
  awesome aurorae though

• Jason Steffen - Rogue Planets and CDM annihilation

  if you make some nice assumptions about cold dark matter, and if it self-annihilates, and if it interacts just enough with matter, then planets could trap dark matter in their interiors and the annihilation could provide internal heat source

  keep rogue free floating planets warm

  yeah, that is extreme, needs a lot of things to work out just right, nut not impossible

  why do particle people keep insisting dwarf galaxies have NFW cuspy profiles for CDM when they clearly do not?

  keep going for 10¹³++ years if it all works

  Steffen & Hooper 2011

  and we are done
  and I am done
  that was an intense week...

That was a bloomin' long meeting, but very very good;
kudos to Fred and Geoff for putting it together, with, of course, invaluable help from their diligent, hard working and highly expert Scientific Organizing Committee.
Modest too.

Coming up we have the Kepler meeting in Dec. '11;
the Planets Around Stellar Remnants at Arecibo in Jan '12, as well as the Exoclimes Winter Workshop at the Aspen Center for Physics, also in Jan '12.

Then, at an appropriate time and place, we will come back to Extreme Solar Systems III at a time and place to be determined...