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...

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