Astrophysics (index)

Atmosphere

(Envelope)
(gas surrounding astronomical object)

An Atmosphere is basically any gas surrounding a celestial body such as a star or a planet. It is sometimes referred to as an Envelope around the body.

A Stellar Atmosphere is the Photosphere and outward, i.e., the part that directly emits or modifies Electromagnetic Radiation (EMR) to space.

A planet or Moon's atmosphere may be a significant part of the mass, e.g., a Gas Giant, or nearly nothing, e.g., the Moon. It is of interest in itself, as hints to the character of the body, and as a factor in Habitability and Biosignatures. Emitted EMR and Transmission Spectroscopy are hints to its makeup, and evidence of chemical mixtures that should not last, i.e., out of Chemical Equilibrium (CE), indicates something replenishing the mixture, e.g., a reaction with the surface, or a emission from inside the planet, or life. Atmospheric Models and Climate Models (e.g., One Dimensional Climate Model, MarsWRF) are created to study and explain planetary atmospheres.

The Earth's atmosphere serves as a well-studied example of a planetary atmosphere, and for its well-understood effects on observation, i.e., Atmospheric Windows and Seeing.

Atmospheric Retention and its lack are of interest, both to explain observations of a body's atmosphere (or its lack) and to establish that an atmosphere is being replenished, if it ought to be gone. Its Temperature, the body's Gravity, and the mass of the molecules determine if some molecules reach escape velocity and are lost: for example, Hydrogen (H) molecules are sufficiently light that the Earth's temperature assured they haven't remained. Photodissociation can break molecules into smaller units, affecting retention, as can Gravitational Separation, i.e., Chemical Differentiation, stratification of the atmosphere by molecular weight.


(planets,stars,gas)
http://en.wikipedia.org/wiki/Atmosphere
http://en.wikipedia.org/wiki/Stellar_atmosphere

Referenced by:
Ablation
Absolute Magnitude (M)
Absorption
Absorption Line
Advection
Aerosols
Airmass
Albedo
Adaptive Mesh Refinement (AMR)
Adaptive Optics (AO)
Apparent Magnitude (m)
ATM
Atmospheric Model
Atmospheric Tide
Aurora
Autoconversion Rate
Black Widow Pulsar (B1957+20)
Baroclinicity
Biosignature
Bow Shock
Brunt-Väisälä Frequency
Carbonate System
Carbon Star
Cassini
Chemical Equilibrium (CE)
Methane (CH4)
Cherenkov Radiation
Chromosphere
Carbon Dioxide (CO2)
Cold Trap
Comet
Cherenkov Telescope Array (CTA)
Diffraction Limited
DISORT
Deformable Mirror (DM)
Earthshine
Exoplanet Eclipse Light Curve
Emission
Ethylene (C2H4)
Extinction
Forbidden Line
Gas Flow
General Circulation Model (GCM)
Gemini Observatory
Giant Planet
GJ 1132 b
GJ 1214 b
Habitability
Acetylene (C2H2)
HITRAN
Homopause
Hydrodynamics
Hydrology
Hydrostatic Equilibrium
Image Stabilization
Kuiper Airborne Observatory (KAO)
Lyman-Break Galaxy (LBG)
Liquid Planet
Lucky Imaging
Mars Express
Mass Spectrometer
Mauna Kea
M Dwarf
Magnetohydrodynamics (MHD)
MITgcm
Mixing Ratio
MUSCLES
Occultation
Optical Depth (τ)
PAH Emissions
Phase Curve
Planet Formation
Radiometer
Ram Pressure
Rayleigh Scattering
Red Noise
Reducing Atmosphere
Radiative Forcing (RF)
Rossby Number (Ro)
Rossby Waves
Radiative Transfer Code (RT Code)
Scale Height (H)
Solar Dynamics Observatory (SDO)
Spectral Energy Distribution (SED)
Seeing
Solar Constant
Stellar Atmosphere
Stellar Temperature Determination
Sublimation
Super-Earth
Surface Temperature
Taylor-Proudman Theorem
Three Dimensional Model
Titan
Transiting Planet
Transmission Spectroscopy
Turbulence
Very-High-Energy Gamma Rays (VHEGR)
Vortex
Water Lines
Atmospheric Window
Wide Field Infrared Explorer (WIRE)

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