Glossary


This is a place to put terms that may be unfamiliar to some, or that mean different things to different scientific communities. Please try to assemble this list in alphabetical order.

chopping

Alternating early/late transit

Conjunction

Closest approach planets

CMB (Astro)

Cosmic microwave background: thermal radiation left over from the Big Bang
(http://en.wikipedia.org/wiki/Cosmic_microwave_background)

CMB (Geo)

Core-mantle boundary: the interface between the metallic core and the rocky mantle.
(http://en.wikipedia.org/wiki/Core%E2%80%93mantle_boundary)

Core (Astro)

The solid portion of a planet (below the atmosphere). For gas-giant planets, the most favored model is that this core (mostly) grows first, onto which gas accretes from the neblua.

Core (Geo)

The metal-rich interior layer of a rocky planet (below the silicate mantle.)

Metal


Migration

Type 1:

Motion of a planet while it is embedded in a gas disk, due to torques it launches in the disk. It is relevant for planets 1-50 M_Earth, or so -- they migrate faster for more massive planets, until...

Type 2:

A planet that is massive enough to open a gap in its disk (about Saturn's mass, depending on disk properties) then migrates slower, migrating along with the viscous evolution of the disk.
Key point --> Both types of migration are subject to many details, discussed by lots of papers.

Open cluster

A loosely-bound set of stars within a galaxy, which formed out of the same cloud (age spread of < a few Myr and small metallicity spread). Such clusters likely unbind, such that their members become "field stars" -- around which exoplanets are found in abundance.

Oxygen Fugacity

Oxygen fugacity is an equivalent of the partial pressure of oxygen in a particular environment (atmosphere, rocks, etc.) corrected for the nonideal character of the gas. (http://link.springer.com/referenceworkentry/10.1007%2F978-3-642-11274-4_4021)
In geology, a redox buffer is an assemblage of minerals or compounds that constrains oxygen fugacity as a function of temperature <and pressure>. (http://en.wikipedia.org/wiki/Mineral_redox_buffer) <modified by Jie Li>.
<Note that oxygen fugacity is typically expressed in terms of the difference in log units with respect to a common redox buffer, e.g., Fe-FeO or iron-wüstite (IW). For the Earth, IW-4 is considered highly-reducing, IW-2 is the condition of core-mantle equilibrium, and IW is considered oxidizing>

Partition coefficient

The ratio of concentrations of two components in a mixture, at equilibrium.

Petrology

The study of rocks (from the Greek πέτρα, petra = 'rock' and λόγος, logos = 'study' )

Refractory (materials)


Small planet

Depends on context, of course, but exoplanet observers often means one without a massive H/He envelope which makes it look much bigger.

synodic period

time between conjunctions

TTV

transit time variation

Xenolith

A rock fragment that is entrained in a larger rock during the formation of that larger rock. For example, a mantle xenolith is a sample of mantle rock that is brought up to the surface in a volcanic eruption.