Planet Formation

Destiny or Chance, Taylor, 2012

• Tzero = 3467 +- 2 MYA earliest crystalline material
• Triton(Neptune) 39K
• Sun 1.4% metallicity ( ~0 to 4% )
• p31 typ galaxy 1e11 stars Milky Way formed stars 10GYA
• p33 Gas clouds H2 100-1000 H/cm3, 1% of galactic volume, 10K, up to 100 LY diam, gas for 1e5 to 1e6 stars
• p34 100 KY cloud collapse to ignition

• p35 red dwarf >75% 80xJupiter / Jupiter 150K accretion energy / Brown dwarf 300K

• p48 Planetesimal Hypothesis dustygrains > boulders > mountains > planetesimals > moon-sized

• p49 like a spiral storm, not a uniform disk
• Goldilocks problem, too much gas, fall into sun

  • [7] Roberge & Kamp "Protoplanets and debris disks" in Exoplanets/Seager.2010 p285

• p67 "Planetary-forming processes in our system seem to be essentially accidental and repetition of the particular sequence of events on another system seems as unlikely as multiple wins in a lottery. If planets share any common factor, it is uniqueness.

• p68 "...such comments fail to understand that planetary formation is essentially stochastic. The processes forming planets are chaotic, with all outcomes possible. Seeking one model is an illusion."
• p73 "For the ice giants, Uranus and Neptune, the answer is also clear. They formed too late to catch much gas before it was all gone."

• p75 1st: accretion of bodies approaching Mars in size < 1MY 2nd: collisions for bodies the size of Earth and Venus, 100 MY

• p76 "material now in Earth and Venus probably came from the entire inner solar system" "...the final outcome, was a matter of chance"
• p78 "Chaos is a major factor in planetary growth"

  • Lithium depletion in solar-like stars: no planet connection / Baumann Astronomy&Astrophysics Vol 519, p. A 87, 2010

Look at Caleb Sharf The Copernican Complex again - what's with the Al26/Mg26 nearby supernova?

• p76 Scharf doesn't actually say too much, the references are about the timing of planetary formation. The radionuclide paper (A PERSPECTIVE FROM EXTINCT RADIONUCLIDES ON A YOUNG STELLAR OBJECT: THE SUN AND ITS ACCRETION DISK, Nicolas Dauphas and Marc Chaussidon) discusses how we can use isotope timing to learn when meteoritic CAI (Calcium Aluminum Inclusions) formed, and thus time the shock collapse of the solar system planets Tzero, when a nearby supernova (or more) triggered the gravitational collapse of the gas cloud that became the solar system. From there, chemistry sorts out longer-lived radionuclide pairs like Hafnium-Tungsten, since Hafnium is rock/mantle-seeking and tungsten is iron/core seeking. We can use that separation to estimate when the moon-sized planetoids formed, and potentially when the Tethys impact occured (the example given is 35 MY after Tzero, but that seems to be only an illustration).

  • NOTE 2019 - the solar system most likely formed in the bubble of a Wolf-Rayet star, according to the Origins project at the University of Chicago in 2017

Under a Crimson Sun

David. S. Stevenson 2013

There are far more red dwarfs than G stars, and they last longer. The author posits that life could form on tide-locked planets near these stars and live on their lower-energy photons.