Astrophysics (index)about

Galaxy

(gravitationally-bound group of stars)

A Galaxy is a group of millions or billions of stars gravitationally bound, such as the Milky Way. Galaxies often have a Supermassive Black Hole in the center. The movement of stars as compared to the mass revealed by the stars indicates there is hidden mass in galaxies, which has been termed Dark Matter.

Galaxy Classification:

dwarf galaxies are small galaxies that can be classified as elliptical or irregular, and can be as small as 100 parsecs across.

Star Formation is most seen in Spiral/Disk galaxies. Elliptical galaxies are considered the results of mergers that have lost their gas, e.g., by going through a Starburst Galaxy stage. Molecular Gas Depletion Time is the time it takes for the gas in a star-forming galaxy to be used. The term Early-Type Galaxy (ETG or Blue Galaxy) designates a galaxy with early-type (hot, blue) stars, indicating recent stellar formation, and Late-Type Galaxy (LTG or Red Galaxy) designates the opposite, with late-type, red stars, whose age-range suggests they are older. This represents a Galaxy Bimodality of galaxies forming stars and not.

The workings of Spiral Arms of a spiral galaxy is not fully certain, with the classic theory consisting of Spiral Density Waves (of higher-density Intergalactic Medium) feeding a visible spiral wave of Star Formation. Many of the created stars will be bright but short-lived, so a traveling line of star formation will lead a line of brightness, a spiral arm.

For the purposes of modeling, especially functions within galaxies, they are often modeled as:


(object type)
http://en.wikipedia.org/wiki/Galaxy

Referenced by:
Abell Catalog
Active Galaxy
AEGIS
Active Galactic Nucleus (AGN)
Alcock-Paczyński Effect
ALFALFA
Alpha CO (αCO)
Arp-Madore Catalog of Southern Peculiar Galaxies (AM)
Adaptive Mesh Refinement (AMR)
Atlas of Peculiar Galaxies (APG)
APM Galaxy Survey (APMUKS)
Arakelian Catalog (Ark)
Astronomical Catalog
Astronomical Quantities
Astronomical Survey
Athena
Atlas 3d
Axisymmetric
AzTEC-3
Balmer Series
Band Shifting
Baryon Acoustic Oscillations (BAO)
Bar
Balmer-Break Galaxy (BBG)
Brightest Cluster Galaxy (BCG)
BDF
Binary Star
Black Hole (BH)
Blind Survey
Baryon Oscillation Spectroscopic Survey (BOSS)
Binary SMBH (BSMBH)
Asiago Supernova Catalog (B/SN)
Bulge
Caldwell Catalog
CALIFA
Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)
Canis Major Dwarf Galaxy
CARMA EDGE
Cold Dark Matter (CDM)
Celestial Mechanics
Cepheid Variable
CFHTLS
Cosmic Gamma Ray Background (CGB)
Catalog Of Galaxies And Clusters Of Galaxies (CGCG)
Circumgalactic Medium (CGM)
Chemodynamics
Cosmic Infrared Background (CIB)
Circinus Galaxy (ESO 97-G13)
Conditional Luminosity Function (CLF)
Cluster Radius
Carbon Monoxide (CO)
Cold Gas
COLD GASS
Color-Color Diagram
Color-Magnitude Diagram (CMD)
Comet Galaxy
Computational Astrophysics
Conservation Law
Cooling Function
Coriolis Force
Cosmic Distance Ladder
Cosmic String
Cosmological Principle
Cosmological Zoom Simulation
Cosmic Evolution Survey (COSMOS)
Council Of Giants
Corotation Resonance (CR)
Conditional Stellar Mass Function (CSMF)
Cerro Tololo Inter-American Observatory (CTIO)
Cygnus A (3C 405)
Dark Flow
Dark Matter
Dark Matter Halo
DEEP2
Deep Field (DF)
Deep Survey
de Vaucouleurs' Profile
Velocity Dispersion (σ)
Deep Lens Survey (DLS)
Dwingeloo Obscured Galaxy Survey (DOGS)
Drake Equation
Dropout
Dwarf Galaxy
Dynamical Friction
Dynamical Instability
Dynamo
EAGLE
Effective Radius (Re)
Extended Groth Strip (EGS)
Ejection
Emission Line Galaxy (ELG)
Elliptical Galaxy
EMPIRE Survey
Epoch of Reionization (EOR)
Epicycle
Epicyclic Frequency
Epoch of Galaxy Formation
Escape Fraction
ESO/Uppsala Survey Of The ESO (B) Atlas
Evaporation
Extinction
Faber-Jackson Relation
Star Formation Feedback
Faint Infrared Grism Survey (FIGS)
Final Parsec Problem
FIRE Simulations
First Galaxies
FORNAX
Frame Of Reference
Fast Radio Burst (FRB)
Fanaroff-Riley Classification
Fairall Galaxy List (Frl)
Fundamental Plane
Gadget-2
Galactic Binary
Galactic Electron Density
Galactic Halo
Galactic Plane
Galaxy Bias
Galaxy Classification
Galaxy Cluster (CL)
Galaxy Filament
Galaxy Formation
Galaxy Group
Galaxy Main Sequence
Galaxy Merger
Galaxy Power Spectrum
Galaxy SED
Galaxy Zoo
Galaxy Evolution Explorer (GALEX)
GALEX Arecibo SDSS Survey (GASS)
GAMA
Gas Flow
Gas Fraction
Gas Fraction Estimation
Gas Streamer
Globular Cluster Luminosity Function (GCLF)
G-Dwarf Problem
Gini/M20
GISMO
Globular Cluster (GC)
GOODS NICMOS Survey (GNS)
Grand Design Spiral Galaxy
Gravitational Lensing
Gravity
Great Attractor
Great Debate
GW170817
Galaxy Zoo 2 (GZ2)
Habitable Zone (HZ)
Halo Abundance Matching (HAM)
Hawaii K-Band Galaxy Survey
Hubble Deep Field (HDF)
Hubble Deep Field South (HDF-S)
Herschel Redshift Survey (HeRS)
HFLS3
Hierarchical Assembly of Galaxies
Hill Radius
Parkes HI Zone Of Avoidance Survey (HIZOA)
Hyperluminous Infrared Galaxy (HLIRG)
Holmberg Radius
Hot DOG
H-R Diagram (HRD)
Hubble Constant (H0)
Hubble Diagram
Hubble Ultra-Deep Field (HUDF)
High-Velocity Cloud (HVC)
Hypervelocity Star (HVS)
IC 342
Intergalactic Medium (IGM)
Interplanetary Medium (IPM)
Iron (Fe)
Interstellar Medium (ISM)
Interstellar Magnetic Field (ISMF)
James Clerk Maxwell Telescope (JCMT)
Kapteyn Universe
Kinematic Distance
KMOS3D
Kiso Survey of Ultraviolet Excess Galaxies (KUG)
Lyman-Alpha Emitter (LAE)
Lambda-CDM model (ΛCDM)
LAMOST
Laniakea Supercluster
Lyman-Break Galaxy (LBG)
Line Broadening
LINER
Luminous Infrared Galaxy (LIRG)
Large Magellanic Cloud (LMC)
Local Group (LG)
Local Sheet
Luminous Red Galaxy (LRG)
Low-Surface-Brightness Galaxy (LSB Galaxy)
Large Scale Structure (LSS)
Luminosity Density
Luminosity Function (LF)
Local Volume (LV)
Lyman-Alpha Forest
Messier 100 (M100)
Pinwheel Galaxy (M101)
Sombrero Galaxy (M104)
Andromeda (M31)
Triangulum Galaxy (M33)
Whirlpool Galaxy (M51a)
Messier 74 (M74)
M82
M87
MACHO
Magnetic Field
Mass-To-Light Ratio (M/L)
Mass Transport
Morphological Catalogue Of Galaxies (MCG)
Messier Catalog (M)
Metallicity (Z)
Gravitational Microlensing
Milky Way
Markarian Galaxy (Mkn)
Mock Catalog
Morgan Classification
N-Body Problem
N-Body Simulation
Nebula
NASA/IPAC Extragalactic Database (NED)
N Galaxy
NGC 2363
NGC 253
NGC 2770
Spindle Galaxy (NGC 5866)
Ammonia (NH3)
N-Point Function
1 Jansky Empty Field Survey (1 Jy)
Oort Constants
Open Cluster
PAndAS
PCA Analysis
Peculiar Velocity
Principal Galaxies Catalog (PGC)
PHIBSS
Planetary Nebula Luminosity Function (PNLF)
POINTE-AGAPE
Polar-ring Galaxy
Polar-Ring Catalog (PRC)
Protogalaxy
PSF Fitting
Quenched Galaxy
Radio Relics
Ram Pressure
Reddening
Redshift-angular Size Relation
Redshift Space
Redshift Survey
Radio Galaxy (RG)
RASS/Green Bank Catalog (RGB)
Radio Galaxy Zoo (RGZ)
Ring Galaxy
Rotation Curve
R-process
Radio Source (RS)
SAGE
Satellite Galaxy
Surface Brightness Fluctuation (SBF)
Second Byurakan Survey (SBS)
Scale Height (H)
Scott Effect
Subaru Deep Field (SDF)
Sloan Digital Sky Survey (SDSS)
Spectral Energy Distribution (SED)
Spitzer Extended Deep Survey (SEDS)
Sérsic Profile
Seyfert Galaxy
Star Formation History (SFH)
Synthetic Field Method (SFM)
Star Formation Rate (SFR)
Star-Formation Rate Stellar-Mass Ratio
Spitzer HETDEX Exploratory Large Area Survey (SHELA)
Sidereal
SIMSTACK
SINS
Supermassive Black Hole (SMBH)
Small Magellanic Cloud (SMC)
Submillimeter Galaxy (SMG)
Supernova (SN)
SN 2014J
Solid Angle (Ω)
Spectral Line
Spiral Galaxy
Stellar Population Synthesis (SPS)
Stellar Population Synthesis Code
Standard Candle
STARBURST99
Starburst Galaxy
Star Count
Star Formation (SF)
Stellar Evolution
Stellar Nucleus
Subaru Telescope
Subgrid-Scale Physics
Submillimeter Astronomy
Supercluster
Superluminal Motion
Surface Brightness
Surface Density (Σ)
Synthetic Spectrum
TAIPAN
Tully-Fisher Relation (TFR)
3C 273
3C 295
3D-HST
Three Dimensional Model
Tidal Arm
Tidal Force
Tidal Tail
Timescale (t)
TiNy Titans (TNT)
21cm Line
Toomre Q Parameter (Q)
2dF Galaxy Redshift Survey (2dFGRS)
Two Micron All-Sky Survey (2MASS)
Type Ia Supernova
Ultra-Faint Dwarf Galaxy (UFD)
Uppsala General Catalogue (UGC)
Ultraluminous Infrared Galaxy (ULIRG)
Ursa Major II Dwarf
Velocity-Metallicity Relation
Virgo Cluster
Virgo
Virial Theorem
VISTA
Voyager
Catalogue of Interacting Galaxies (VV)
VIRMOS-VLT Deep Survey (VVDS)
Weak Lensing
Westerhout Radio Survey (W)
Wide-Field Multi-Object Spectrograph (WFMOS)
WINGS
Wolf-Rayet Galaxy
Zone Of Avoidance (ZOA)

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