User:Astredita

Totally metal stars: turbulent concentration of C,O,Si

 * New Class of Stars Are Entirely Metal
 * Some Stars are Totally Metal: A New Mechanism Driving Dust Across Star-Forming Clouds, and Consequences for Planets, Stars, and Galaxies, Philip F. Hopkins, 20 Jun 2014
 * Turbulence produces density fluctutations of large dust-grain elements, especially C,O,Si relative to gas.
 * In sufficiently large molecular clouds the spatial extent of these fluctuations would be larger than pre-stellar cores, thus altering the chemical abundance of stars.
 * In the extreme case leading to stars made totally of "metal". (i.e. non-H/He)

Effect on planet formation

 * More metallicty means form faster, which in turn means accrete more gas before it dissipates leading to larger planets? Also larger rocky cores? So remnant cores of evaporated gas giants could create super-jupiter or even brown-dwarf-mass rocky planets?
 * Rocky planets with larger silicate mantles?
 * Planets with large CO,CO2 or CH4 atmospheres?
 * Super-Neptunes: Super-Jupiter or brown-dwarf-mass planets with large H20/CH4 mantles?

Effect on low-mass star, brown dwarf and free-floating planet formation

 * Normal star formation proceeds all the way down to Jupiter-mass objects
 * Would higher metallicity clouds have less opacity, meaning slower heat-loss meaning only larger objects could gravitationally collapse? Or would larger gravity of dustier clouds mean the cloud is held together longer so that even smaller objects could be formed?

Books

 * Encyclopedia of the Solar System, 3rd edition, 2014, Tilman Spohn, Doris Breuer, Torrence Johnson
 * Comparative Climatology of Terrestrial Planets, 2014, Stephen J. Mackwell, ‎Amy A. Simon-Miller, ‎Jerald W. Harder

Minerals and life

 * The Origins of Life, Robert Hazen, Broadcast date: April 29, 2014
 * Why Complex Mineral Surfaces Could Be Indications Of Life, Elizabeth Howell - Jun 9, 2014

Binary planets
"A las-er" Extrasolar Binary Planets I: Formation by tidal capture during planet-planet scattering, H. Ochiai, M. Nagasawa, S. Ida, 26 Jun 2014

Lack of co-orbital planets
Disruption of co-orbital (1:1) planetary resonances during gas-driven orbital migration, Arnaud Pierens, Sean Raymond, 19 May 2014

Cold Exoplanets
aas224 wed jun 4 2014 230pm-240pm WFIRST-AFTA: What Can We Learn by Detecting Thousands of Cold Exoplanets via Microlensing? Matthew Penny, Department of Astronomy, Ohio State University, Columbus, OH, United States. The WFIRST-AFTA microlensing survey will monitor a few hundred million stars in the Galactic bulge every ~15 minutes to measure the microlensing signatures of thousands of both bound and free-floating planets with masses ranging from super-Jupiters down to that of Ganymede. This huge sample of cold planets will perfectly compliment the sample of warm and hot planets that have been found by Kepler and will be further expanded by TESS and PLATO. I will review the measurements that WFIRST-AFTA will make for each of the planets it finds, and attempt to predict the impact that these will have on our understanding of exoplanet demographics and the planet formation process.

Nitrogen delivery

 * A Possible Nitrogen Barrier to Life Around Cool Stars, Apai, D.; Pascucci, I. July 26-30, 2010
 * The Nitrogen Problem: Constraints on the Delivery of Nitrogen to Rocky Planets, Presented by: Daniel Apai Broadcast date: September 14, 2010

Magnesium silicon ratio

 * Shim Sang-Heon: Un-Earth-Like Interiors of Earth-Like Exoplanets
 * High silicon - MgSiO3Pyroxene+Silica - Mg2SiO4Olivine+Pyroxene - Olivine+MgO - High Magnesium
 * effect on tectonics
 * in lower mantle Pyroxene compresses to MgSiO3perovskite (silicate perovskite). Mg2SiO4Olivine to MgOferropericlase. also intermeditate forms at inbetween pressures in upper mantle
 * Earth's lower mantle 70% perovskite, 30% ferropericlase

optics

 * HOMES - Holographic Optical Method for Exoplanet Spectroscopy
 * A new twist in the properties of light
 * Quantum telescopes, Aglae Kellerer, 26 Mar 2014
 * Diophantine optics

circumplanetary disk
Circumstellar disks can have spiral arms like a galaxy. What about circumplanetary disks? Can you have a planet with arms?

atmospheres
initial hydrogen envelope, hydrodynamic escape, outgassing, impacts, lockup, geochemical cycles, freezing and sublimation

desert planets to ocean planets

 * Different distance from star and different atmospheric pressure means different chemicals are liquid to form oceans, and different chemicals are solid to form Sand, Silt, Clay, Rock, Mud.


 * In these notes ocean planet refers to any solid planet with 100% surface covered by liquid (and not only to planets with subtantial fraction of bulk mass made of water which are often referred to as ocean planets.) Here desert planet refers to high Land to ocean ratio.

Metal/mineral deserts to metal/mineral oceans

 * Refactory materials are liquid at high temperatures and/or pressures
 * metal/mineral oceans i.e. lava
 * solid land made of materials with higher melting point
 * sand made of?
 * polar caps of metal
 * plate tectonics of iron continents in a sea of silicate?
 * from metal lakes with mostly iron land and salt deserts?, to metal oceans, to global metal ocean world
 * eccentric orbit otherwise tidally locked or Venus-like nearly locked

Corot-7b
"Using the MAGMA code (Fegley and Cameron, 1987; Schaefer and Fegley, 2004) we can compute the evolution of the oceanic composition with time, starting from a silicate composition (Schaefer and Fegley, 2009). Fig.5 shows its radical changes as evaporation proceeds, the abundance of refractory species (MgO, SiO2, then TiO2, CaO, Al2O3) increases with time, and the total vapour pressure decreases (Fig.6). Eventually, at high vaporized fractions (Fvap > 0.95), the composition of the refractory residue remains stable, with mole fractions of 13% for CaO and 87% for Al2O3 at 2200 K (close to the composition CaO.6Al2O3), which we propose for the composition of the ocean after a 1.5 Gyr evolution."
 * The extreme physical properties of the CoRoT-7b super-Earth, A. Léger et al.
 * described as a "A lava-ocean world" but it is not completely lava-ocean, only on tidally-locked dayside, so not a lava ocean-world but a solid-surface world with a lava ocean on one side. Minimal rocky-atmosphere only 1.5Pa. So lava can be liquid without atmosphere. Lava on Earth is viscous but on Corot-7b lava is much hotter so is much less viscous. (like liquid water at -20C)
 * also not lava in a volcanic sense but in a hot liquid rock sense from stellar heat.

Water deserts to water oceans

 * Venus all dried out, some sand dune regions but not many
 * Earth 70% ocean 30% land
 * Mars partially dried, atmosphere presently too thin and cold for liquid water ocean, water frozen exists especially at higher latitudes

Water/ammonia mixture deserts to Water/ammonia oceans

 * Water/ammonia mixture in Uranus, Neptune and probably in icy moons' subsurfaces
 * no known example of rocky planet with Water/ammonia surface oceans
 * what would surface rock be made of at these temperatures? what would sand be made of? atmosphere?

hydrocarbon deserts to hydrocarbon oceans

 * Titan is a hydrocarbon desert world, lakes of hydrocarbons, and sand of organic materials, and rocky surface mostly made of nitrogen but also water/ammonia lava deposits
 * exo hydrocarbon oceans
 * exo hydrocarbon ocean planet

nitrogen deserts to nitrogen oceans

 * liquid nitrogen requires atmosphere pressure, temp and composition?. hydrogen? cold planets around red dwarfs?
 * exo nitrogen oceans
 * exo nitrogen ocean planet
 * what would surface rock be made of at these temperatures? what would sand be made of?
 * Triton? Pluto? KBOs?
 * argon/neon lava?

Other

 * Earth has varying cloud cover/clear skies but mostly clear atmosphere, but Titan is completely hazy atmosphere. Will any of the other ocean types have clear atmospheres and variable cloud cover or will they all be total clouds and haze? Opacity at some wavelengths but clear at others?


 * Will glaciation/solidification periods happen on other ocean types or will the solid phases of other materials not be more reflective than liquid phases so no feedback loop?


 * Under what conditions will planets have clouds/rain/lakes of different compositions/mixtures at different latitudes?


 * What will aquifers, sinkholes and other near surface liquid and erosion look like for different land composition and liquid composition?


 * What are deserts to oceans like in high carbon exosystems and with other non-solar-like compositions?
 * What do tidally heated exomoons with thick atmospheres (unlike Io) look like at different distances from star and planet and around planets of different masses?


 * Lower metallicity protoplanetary disks have smaller planets. Smaller planets tend to be closer together and more of them than when giant planets are present. (at least in close-in orbits, will this trend continue further out?) Does this also apply to protosatellite disks? is that why Galilean moons are larger and less numerous than the icy moons of Saturn? Jupiter's location in solar system more metallic than Saturn's location. Would Neptune have had lots more small moons before Triton arrived?


 * Hotter stars mean distance from star at a given temperature is further out so the separation of the disk into snow-lines of substances with different condensing points will be more spread out? so planet compositions will be less mixed? so more different than their neighbouring planets?


 * Stars and systems of different masses will have different rotation. Planets will rotate faster in some systems than others? Shorter day/night cycle. Less time to warm up/cool down. Less day/night temperature variation.

Ammonia contamination of habitable zones of cool planetary systems

 * ammonia water


 * In the solar system the snow-line for water formed further out than Earth. The deuterium/hydrogen ratio of Earth's oceans matches the asteroid belt so that's probably where Earth's water was deliverd from by asteroids hitting Earth. If there was no Jupiter to prevent asteroid belt from coalescing into single mass then less asteroids then Earth would have very little water? No, giant planets are not needed for water delivery according to The Effect of Planets Beyond the Ice Line on the Accretion of Volatiles by Habitable-Zone Rocky Planets by Elisa V. Quintana and Jack J. Lissauer


 * In the solar system ammonia formed in the protoplanetary disk far enough out beyond the asteroid belt and was swept up by Jupiter and its moons so the ammonia didn't reach Earth?


 * In planetary systems which receive less heating from their star, the snow lines of different substances will be spread out over shorter distances from star therefore the water will be more mixed with ammonia?


 * "There is evidence for “oceans” of water and water/ammonia within Callisto and Europa, and these may also be present in Titan (Showman and Manotra, 1999). These “oceans” are expected to be extremely basic, conditions under which the terrestrial nucleic acids and proteins would be rapidly hydrolyzed and most terrestrial biochemistry would be thermodynamically unworkable."


 * Will ammonia concentration remain stable or are there processes that remove the ammonia over geological timescales and decontaminate the planet?


 * Does ammonia concentration change with depth/pressure?


 * high temperature at deep sea vents, black smokers cause ammonia gas to bubble upwards creating pockets of pure water giving life chance to evolve in pure water before adapting to  surrounding ammonia waters? so water/ammonia oceans should be considered habitable? so habitable zones move further out? except too far out means so much water in protoplanetary disk that land is completely submerged and water turns into high-pressure ice phases.

Acid oceans and base oceans

 * Apart from ammonia water what other large concentrations?
 * Can you have large amount of carbon dioxide or sulphur acidic ocean at a distance from star where temp means ocean will not boil away?

Total mix: rocky land, water/ammonia ocean, hydrocarbon surface

 * Can you have temp cold enough for liquid hydrocarbons, but atmosphere pressure high enough for liquid water/ammonia ocean with the hydrocarbons floating on top, but not so much ocean that land is submerged? Protoplanetary disk needs to be mixed enough to have rock/water/ammonia/hydrocarbons suggests very cool star such as brown dwarf? If atmosphere is thick enough for liquid water/ammonia then can it also be cool enough for liquid hydrocabons? Brown dwarf protoplanetary disks depleted of water so perhaps no danger of land being submerged in water.

habitable zone when carbon habitable zone coincides with liquid water habitable zone
Protoplanetary disk composition and chemistry around different types of star produce carbon stored in different molecules in different amounts at different distances from star. So habitable zone when carbon habitable zone coincides with liquid water habitable zone? Too much carbon then oxygen will combine with it instead of hydrogen meaning no water. Too little carbon and there is no life.

Nitrogen planets
As mentioned in Extrasolar Carbon Planets, Nitrogen planets could perhaps form as a result of nitrogen rich envelopes around AGB stars.

Rocky nitrogen planet with earth temperature:
 * Atmosphere: Nitrogen, Oxygen, Nitrogen oxides, Carbon nitrides?
 * Ocean: Nitrogen hydrides, ammonia, cyanides?
 * Land and Mantle: Silicon nitride, Silicon carbide ?
 * Core: Iron?

Compare with carbon modification relative to Earth-like composition: The Compositional Diversity of Extrasolar Terrestrial Planets: I. In-Situ Simulations, Jade C. Bond, David P. O'Brien, Dante S. Lauretta, 6 Apr 2010

If nitrogen planets come from second-generation accretion disks produced by AGB stars in binary star systems, then if the accretion disk around remaining main-sequence star is highly inclined relative to its existing planetary system then rocky nitrogen planets could have the compositions listed above. However if the accretion disk is aligned with the first disk then the first generation planets would become enveloped in nitrogen-rich layers, and they could completely melt and mix with their new nitrogen envelope.

Venus
"suggested by our simulations is that a planet with modern Earth's atmosphere, in Venus' orbit, and with modern Venus' (slow) rotation rate would be habitable. This would imply that if Venus went through a runaway greenhouse, it had a higher rotation rate at that time." Strong Dependence of the Inner Edge of the Habitable Zone on Planetary Rotation Rate, Jun Yang, Gwenael Boue, Daniel C. Fabrycky, Dorian S. Abbot, 19 Apr 2014
 * Venus’ crust heals too fast for plate tectonics, Shannon Palus Apr 21 2014, arstechnica.com

Misc

 * Characterizing the purple Earth: Modelling the globally-integrated spectral variability of the Archean Earth, E. Sanromá, E. Pallé, M. N. Parenteau, N. Y. Kiang, A. M. Gutiérrez-Navarro, R. López, P. Montañés-Rodríguez, Submitted on 5 Nov 2013
 * Continents on Alien Worlds Could Hint at Extraterrestrial Life, by Charles Q. Choi, Astrobiology Magazine Contributor  |   January 13, 2014
 * Investigating Nearby Exoplanets via Interstellar Radar, Louis K. Scheffer, 14 Jan 2013
 * First images on the sky from a hyper telescope, E. Pedretti, A. Labeyrie, L. Arnold, N. Thureau, O. Lardiere, A. Boccaletti, P. Riaud, 28 Sep 2000


 * The outer regions of extrasolar planetary systems, EWASS 2014 : European Week of Astronomy and Space Science, 30 June — 4 July 2014, Geneva, Switzerland


 * WFIRST Direct imaging Exoplanet Science with AFTA-WFIRST


 * Scientific Exoplanets Renderer (SER)


 * Searching for planets around pulsars and radio-quiet neutron stars, Posselt, B.; Neuhäuser, R.; Haberl, F. 40 YEARS OF PULSARS: Millisecond Pulsars, Magnetars and More. AIP Conference Proceedings, Volume 983, pp. 360-362 (2008).