ExSSII: death and destruction

Final day of Extreme Solar Systems II here at Jackson Lake, and what a beautiful day it is..

And we are live for session 8 of day 5.

Thursday night there was, again, an after dinner informal discussion, with the topic being "planets in binary systems" - the panel highlighted the theoretical difficulties with forming and retaining planets in binary systems, and there then followed a very lievely discussion.

Doug Lin, as it happens, with a collaborator, had used the generous 2 hour break for dinner to come up with and run a model for Kepler-16b formation, and a number of people had great fund picking the model to pieces.
I'm tempted to make a comparison here with "bear baiting", but I won't ;-)
As someone realised during the discussion, Doug's model is similar to one by Nelson and collaborators, that arguably predicts K-16b (Piersen (sp?) and Nelson 2008).

Obviously, in 2 hours, not all the quantitative nuances can be worked out at the level of detail required, but Doug's model is very plausible and may well survive the process.
I took some shots at it last night, and Doug gently straightened me out early this morning over coffee...

Feeling well straightened out, we now go to the presentations:

  • Dimitri Veras - The Great Escape
    and I rest and upload my own talk, better late than never...
  • Eva Villaver - Planets Around Evolved Stars
    reviewing mass loss processes and engulfment vs orbit expansion
    focusing on intermediate mass stars (more massive than solar
    Jovian planet around a [Fe/H] = -2 primary?
  • Kevin Luhman - Coolest Known Brown Dwarf
    new class of ultra-cool brown dwarfs at wide separation and/or in isolation
    comoving companion to white dwarf, found using Spitzer
    huge angular separation - very wide orbit
    very red, very faint - J band deep images give 300-340K, ~ 2 Gyr age
    mass estimate (model dependent) 6-9 M_J !
    Crossing brown dwarf/planet barrier - but Kevin says it should really be a substellar object

    now several known "Y dwarfs" - the new class of brown dwarfs
    astronomers really like to find new labels for subclasses of objects....

    Todorov et al 2010 - hierarchical quadruple in Taurus,
    M star with brown dwarf companions, lowest mass seems to be under 10 M_J

    Lowest mass brown dwarfs less massive than most massive giant planets

  • Boris Gaensicker - Planetary Debris Disks Around Young White Dwarfs
    metal lines seen in white dwarf photospheres, ought to not be there, settling time is short
    metal lines are variable, must be replenished
    consistent with rock debris, low C - baked out in volatiles?
    consistent with km3 of material deposited intermittently

    significant fraction of young white dwarfs have massive dusty debris disks,
    also several known white dwarfs with warm metal rich gaseous disks, at radii of order a solar radius or less
    Planet in orbit around white dwarf perturbs planetesimals which get tidally disrupted leaving dust and/or gas disk

    as predicted in the truly great paper by John Debes back in 2002 ;-)

    20% of white dwarfs (age ~ 100Myr - Gyr) are accreting metals

  • Amy Bonsor - Polluted White Dwarfs
    conservation of Tisserand parameterr during daisy chain scattering by planets on circular orbits, in restricted approx.
  • Eric Agol - Earths Transiting White Dwarfs
    Looking for earth transits of white dwarfs
    hoping for planets at 0.01 AU - in the WD habitable zone
    WDs cool slowly, so CHZ endures, but VERY narrow
    outside tidal disruption limit, within circularization limit
    so inside progenitor red giant envelope
    tricky
    Eric wants to form an Earth at 0,01 AU post RGB

    Don't believe it.

    Editorial Comment: can scatter Earths from ~> 1 AU down to 0.01 AU after RGB phase,
    BUT, eccentricity necessarily high, so to circularize at 0.01 AU periastron has to be closer in [ (1-e) vs (1-e^2) ] - odds of hitting the target is But, circularization energy is comparable to planet binding energy - must be because periastron is close to tidal disruption limit (within factor of 2)
    therefore planet must be bulk melted during circularization
    So, low probability, volatiles likely baked out and re-establishing life unlikely

    This is so unlikely, that I'd be tempted to consider any planet in the WD habitable zone to be evidence of intelligent life with serious astroengineering capabilities...

  • Hagai Perets - Planetary Dynamics in Evolved Binary Systems
    binary stability regions - dynamically unstable zones
    these shift during stellar evoluition with mass loss
    cute animation

    And we are back from a too short coffee break:

  • Youdin - review of planet formation issues
    cute local pics to illustrate concepts
    observations inform/constrain formation models - crazy talk dude
    Kepler obs sloppy statistics by people making inferrences

    Lack of 3 R_E planets implies we're seeing transition between Neptunes (gas rich) and Super-Earths (rock/iron)?
    Maybe, suggestive.

  • Quintana - K-11b,c,d,e,f,g
    new sims on dynamics and formation scenarios
    dense 6-pack, low mass nearly coplanar
    GV star (stellar radius seems a bit big for mass 1.1 vs 0.95 - subgiant??)

    35 earth masses within 0.25 AU of star
    Sims looking for formation scenarios for this system and whether to expect more planets.

  • Moro-Martin - planetesimal belts
    after the gas is gone
    look for dust signatures for cracked and baked rocks
    see warm dust around range of primaries
    Spitzer did good work
    see gaps in disks (mostly indirect from evidence of lack of emission over some Teff range from integrated spectra - some resolved disks with gaps) - expect planets to carve out gaps in disks

    more on Subaru search
    Herschel also looking - does a bit better than Spitzer at large radii/cool dust

  • Loehne - HD 207127
    dusty debris disk at large radii - 145 AU annulus
  • Ida - planet formation - pop synth
    massive monte-carlo/nbody sim of planet formation,
    trying to incorporate physics to explain observed distributions of planets,
    modulo biases and selection effects,
    and predict future discoveries
    series of papers
    covers lot of parameter space

    we still don't understand migration in detail

  • Mordasini - more pop synth
    more massive parametric studies
  • Jang-Condell - warps and reversing type I migration
    warped disks self-shadow, may stop unwanted migration

    gotta go to a meeting.
    Lunch break.

Session 9 - last session, but clearly the best, starts in an hour.

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