Planet Masses and Radii from Physical Principles Günther Wuchterl CoRoT / DLR Thüringer...
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Transcript of Planet Masses and Radii from Physical Principles Günther Wuchterl CoRoT / DLR Thüringer...
Planet Masses and Radiifrom
Physical Principles
Günther WuchterlCoRoT / DLR
Thüringer Landessternwarte Tautenburg
A theory for the discovery era
General – all stars, all orbital periods, core: y/n Simple – direct relation to physics Robust – no a-priori selection of mechanisms Predictive - no free parameters Fast – evaluation feasible to better than
observed accuracy in entire discovery space
General Theory of Planet FormationAssumptions and Principles
Diversity of nebulae: study planet formation in any gravitationally stable nebula for all stellar masses,
Strong planetesimal hypothesis: there are always enough planetesimals,
Study all planets with cores of all masses including zero - do not separate into nucleated instability or disk instability;
ADS: see Pečnik, Broeg, Schönke, Wuchterl
I: Full study of a simple modelIsothermal Planets
How to determine and classify all planets and protoplanets?
Characteristic mass: The Ω-point
natural planetary mass derived from microphysics , primary mass, and orbital period.
Compactification proto -> planet by self gravity
PLANET ESSENTIALSIsothermal planets: Pečnik 2005Analytical Theory: Schönke 2007
Envelope self-gravity Gravity and tides of primary (Hill-sphere) Compacting by core-gravity and self-gravity
Star (luminosity+tides) + nebula = planets
Why does this work?
Think of planet formation as analogy to the van der Waals gas with gravity as the long-range force,
Take planets as analogy to the liquid-phase in coexistence with a gas-phase, the nebula.
Find out more at
Pečnik and Pečnik+W for the isothermal case Schönke 2007 etc., for stability and analytics Broeg and Broeg+W for realistic planets Wuchterl et al. for the CoRoT-stellar-mixture Broeg, Icarus 2009
II: Planets with Energy Transfer
Detailed non-ideal equations of state, Energy transfer by radiation and convection, Detailed opacity: “stellar”, molecular, dust, Energy-input by planetesimal accretion.
Main sequences: stars and planets
Stars Mostly hydrostatic Energy balance on
main sequence Complete equilibria
on main sequence Mostly constant mass
Determine: L,R-->Teff
Planets Mostly hydrostatic Energy balance when
young Complete equilibria in
the nebulae Mass exchange with
the nebulae Determine: M, R
Step 1: Masses
Consider host star and orbital period Planetary equilibria with all core masses:
hydrostatic equilibrium (P vs. core and gas) thermal equilibrium (L vs. planetesimal accr.)
Balance: force: planet with nebula pressure, and Thermal: planetesimal heat with radiation into
equilibrium temperature nebulae Count all possible planets in any stable nebula
Get planetary initial mass function, for M*, Porb
1: 2006 Dec. 26th: CoRoT Launch Prediction: Planetary Masses from
Formation TheoryWuchterl et al.; 2006+n, Lammer et al. 2006+n
Dec. 26th: astro-ph/0701003 ;astro-ph/0701565
Planetary masses and distributionsM to A stars
orbital period up to 128 days
CoRoT - Mark 1: Dec 2005CoRoT - Mark 2: Sept 2007CoRoT - Mark 3: June 2008
At Chris Broegs webpagewww.space.unibe.ch/~broeg/
Or search“CoRoT survey Mark3”
Step 2: Radii
Initial masses and initial interior structures for the “IMF”-ensemble of planets found in step 1
Evolution of planetary populations: switch-off planetesimal accretion nebula decompression (if any) follow contraction/expansion to determine R
Case-study: CoRoT-13b A Jupiter with monster core
Host star: G0V, 1.1 M_Sun, 5945 (± 90) K Mass: 1.308 (± 0.066) MJ Semi major axis: 0.051 (± 0.0031) AU Orbital period: 4.03519 (± 3e-05) days Radius: 0.885 (± 0.014) RJ → density is almost twice Jupiter's 150 – 300 Earth masses of heavy elements!
#CoRoT-13b 4.04d,G0V,0.12−3.15Ga lg:-0.92,0.50=-0.21+/-0.71;1.308±0.066 MJ,0.885±0.014,lg=(27.37,27.42),RJ,2.34±0.23g/cm3
Mass function and CoRoT-13b
#CoRoT-13b 4.04d,G0V,0.12−3.15Ga lg:-0.92,0.50=-0.21+/-0.71;1.308±0.066 MJ,0.885±0.014,lg=(27.37,27.42),RJ,2.34±0.23g/cm3
Conclusion – General Theory
Predicts high resolution mass and radius distributions from basic physics for planets of
M to A stars and; orbital periods up to 120d;
Bimodal mass and radius distributions; Large gaps between “Jupiters” and “Neptunes”; Explains M,R,t of extreme planets as the ~200
M⊕ monster core of CoRoT-13b (and others).