Context: planet formation theory
Results: embedded planet core
Core accretion in MHD simulations
of layered protoplanetary discs
Oliver Gressel ?
Niels Bohr International Academy (NBIA), Copenhagen
Richard P. Nelson (QMUL, London)
Neal J. Turner (JPL-Caltech, Pasadena)
Udo Ziegler (AIP, Potsdam)
February 10/11, 2014
Star and Planet Formation for All
?
O. Gressel
[email protected]
2014-02-10 – SnPFfA Lund
1/13
Context: planet formation theory
Results: embedded planet core
gas giant interiors
Image Credit: NASA, Lunar and Planetary Institute
O. Gressel
2014-02-10 – SnPFfA Lund
2/13
Context: planet formation theory
Results: embedded planet core
motivation
our goals
core accretion picture
1D spherical envelopes
I: quasi-static contraction
II: runaway growth phase
O. Gressel
identify . . .
accretion time-scales
role of circumplanetary disc
potential bottle-necks
influence of magnetic field
2014-02-10 – SnPFfA Lund
3/13
Context: planet formation theory
Results: embedded planet core
schematics of protostellar disc
Armitage (2011)
O. Gressel
2014-02-10 – SnPFfA Lund
4/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
spiral arms and gap
isothermal HD
non-isoth. HD
O. Gressel
non-isoth. MHD
2014-02-10 – SnPFfA Lund
5/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
spiral arms and gap
isothermal HD
non-isoth. HD
O. Gressel
non-isoth. MHD
2014-02-10 – SnPFfA Lund
5/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
spiral arms and gap
isothermal HD
non-isoth. HD
O. Gressel
non-isoth. MHD
2014-02-10 – SnPFfA Lund
5/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
gap opening
Saturn-mass planet
rapid growth phase
Hill-sphere radius
' gas scale height
Gap opening
play
via tidal torques and
gas accretion
onto planet core
formation not complete
gap contrast of 20–30
O. Gressel
2014-02-10 – SnPFfA Lund
6/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
embedded sub-disc
isothermal HD
non-isoth. HD
O. Gressel
non-isoth. MHD
2014-02-10 – SnPFfA Lund
7/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
embedded sub-disc
isothermal HD
non-isoth. HD
O. Gressel
non-isoth. MHD
2014-02-10 – SnPFfA Lund
7/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
embedded sub-disc
isothermal HD
non-isoth. HD
O. Gressel
non-isoth. MHD
2014-02-10 – SnPFfA Lund
7/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
disc variability
O. Gressel
2014-02-10 – SnPFfA Lund
8/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
the circumplanetary disc
Disc rotation profile
sub-keplerian rotation
inner disc hotter
→ pressure support
CPD extends to about
half the Hill radius
Disc surface density
non-isoth. case:
flat surface density
isothermal case:
steeper profile
m = 2 spiral arms
O. Gressel
2014-02-10 – SnPFfA Lund
9/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
the horseshoe region
isothermal HD
non-isoth. HD
O. Gressel
non-isoth. MHD
2014-02-10 – SnPFfA Lund
10/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
the horseshoe region
isothermal HD
non-isoth. HD
O. Gressel
non-isoth. MHD
2014-02-10 – SnPFfA Lund
10/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
the horseshoe region
isothermal HD
non-isoth. HD
O. Gressel
non-isoth. MHD
2014-02-10 – SnPFfA Lund
10/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
accretion flow properties
play
O. Gressel
2014-02-10 – SnPFfA Lund
11/13
Context: planet formation theory
Results: embedded planet core
global properties / PPD
local properties / CPD
circum-jovian jet
predicted theoretically by Quillen & Trilling (1998) and Fendt (2003)
O. Gressel
2014-02-10 – SnPFfA Lund
12/13
summary of results
Gap opening process
incomplete, but contrasts of 20–30 reached
in the MHD model: enlivening of the dead zone
Core accretion
spin-out circumplanetary disc
mainly vertical inflow of low-metallicity gas
→ efficient cooling of contracting envelope (!?)
high accretion rate (∼ 8 × 10−3 M⊕ yr−1 )
→ Jupiter size after ∼ 30, 000 yr
Launching of a planetary jet
tornado-like flow drags down azimuthal field
swirling → helical field → magneto-centrifugal jet
disc wind important for CPD accretion (!?)
O. Gressel
2014-02-10 – SnPFfA Lund
13/13