Astrophysics (Index)About

star

(astronomical body shining from fusion energy)

A star is one of the light-colored dot-like points seen in the night sky that do not shift around the celestial sphere. Science accepts that these dots are distant astronomical objects much like the Sun, that emit EMR using energy produced by fusion, and science uses the term star for such objects, thus the Sun is considered a star. Such criteria requires some specifics, and exact criteria does vary with context, even within science. The general scientific definition is a body of gas that is large and hot enough that it initiates fusion. Main sequence stars clearly qualify as do post-main-sequence stars, e.g., on the red-giant branch. The eventual stellar remnants (which no longer host fusion) are sometimes still termed stars or a special kind of (qualified) star: neutron stars and white dwarfs do shine, but a stellar-mass black hole arguably does not, yet is often termed a star, e.g., as a binary companion. YSOs and pre-main-sequence stars, presumed to have fusion in their future, are likely to be termed stars if they shine like stars; they begin such shining some time before they trigger fusion, shining due to their hot temperature caused by the Kelvin-Helmholtz mechanism. Brown dwarfs (as a group) are often classified as stars: most are not currently undergoing fusion, but they are defined as bodies that host deuterium fusion sometime during their life. The distinction between brown dwarfs and gas planets is clear in principle, but classifying a particular object from observation data can be difficult or impossible. A rule of convenience that has been standardized is that lacking a reasonable determination, any such body for which the mass is determined to be less than 13 Jupiter masses is nominally classified as a planet, thus presumed not a brown dwarf and not a star. Numerous aspects of stars are of interest in astrophysical research, among them:

Much of what is known about stars was learned studying the Sun, and a surprising amount is from the study of binary stars and variable stars. Spectrography and parallax measurement have been key to their study. See also entries on individual stars, star types, and other star topics.


(astronomy,object type)
Further reading:
https://en.wikipedia.org/wiki/Star
https://en.wikipedia.org/wiki/Astronomy#Stellar_astronomy
https://en.wikipedia.org/wiki/Category:Stellar_astronomy
https://en.wiktionary.org/wiki/star
https://astronomy.swin.edu.au/cosmos/s/star
https://www.britannica.com/science/star-astronomy
http://www.stellar-database.com/intro.html
https://www.vaticanobservatory.va/en/research/highlights/stellar-astronomy

Referenced by pages:
47 Tucanae (47 Tuc)
51 Eridani b
51 Pegasi b (51 Peg b)
A-LIST
A-type star (A)
AB system
absolute magnitude (M)
accretion rate
adaptive mesh refinement (AMR)
adaptive optics (AO)
age-velocity-dispersion relation (AVR)
Airy disk
Alpha Centauri (α Centauri)
alpha element
alpha process (α process)
alpha-enhanced
aluminum (Al)
angular distance
APOGEE
apsis
arcsecond (arcsec)
Arcturus
asteroseismology
astrograph
Astrographic Catalog (AC)
astrometric binary
astrometry
astronomical catalog
astronomical object
astronomical symbol
asymptotic giant branch (AGB)
ATLAS Stellar Model
atmosphere
B-type star (B)
Balmer jump (BJ)
barium star (Ba star)
barrier
BaSTI
BATC
Bayer designation
Be star
Betelgeuse
binary companion
binary star
Birkhoff's theorem
black-body radiation
BlackHoleCam (BHC)
blind survey
blue horizontal branch (BHB)
blue loop (BL)
Bok globule
bolometric correction
bolometric magnitude (Mbol)
Bonner Durchmusterung Catalog (BD)
bow shock
brightest cluster galaxy (BCG)
BRITE-Constellation
brown dwarf (BD)
Bruce Proper Motion Survey (BPM)
BT-Settl
bulge
BUSS
calcium (Ca)
Canada-France-Hawaii Telescope (CFHT)
candidate companion (CC)
carbon star (C)
Catalog of Azzopardi & Vigneau (AzV)
celestial coordinate system
celestial sphere
chemical equilibrium (CE)
chemical tagging
chemically peculiar star (CP star)
chromatic aberration
circumbinary planet
circumstellar disk
circumstellar envelope (CSE)
Cloudy
cold gas
collapsar
color index
color-color diagram (CCD)
column density
compact object (CO)
comparator
computational astrophysics
conditional luminosity function (CLF)
constellation
convection
cooling function
core collapse
core collapse supernova (CCSN)
Coriolis force
coronal mass ejection (CME)
corotation resonance
cosmological simulation
Danjon astrolabe
DAOPHOT
dark age
dark galaxy
dark matter (DM)
dark matter filament
dark nebula
Dartmouth Stellar Evolution Database (DSED)
decretion disk
dense core
diffractive interstellar scintillation (DISS)
DISORT
double star
double-line spectroscopic binary (SB2)
dredge-up
dusty galaxy
dwarf galaxy
Dynamical Analysis of Nearby Clusters (DANCe)
dynamical friction
eclipse mapping
eclipsing binary (E)
Eddington approximation
Eddington bias
Eddington luminosity
effective temperature (Teff)
electron capture
electron pressure
electron screening
emission nebula
emission-line star
epicycle
epicyclic frequency
epoch
epoch J2000.0
epoch of reionization (EOR)
ESPEX
evaporating gas globule (EGG)
event horizon (EH)
evolutionary track
exotic star
extended source
extinction
extremely metal poor galaxy (XMPG)
F-type star (F)
FGK star
field star
final parsec problem
fixed star
flux-weighted gravity-luminosity relationship (FGLR)
foe
FORNAX
free-fall time
free-floating planet (FFP)
Güdel-Benz relation
G-type star (G)
GaiaHub
galactic bulge
galactic center
galactic plane
galaxy age determination
galaxy bias
galaxy main sequence
Gamow peak
General Catalogue of Trigonometric Parallaxes (GCTP)
giant star
Gliese-Jahreiss Catalog (GJ)
gravitational potential energy
gravitational redshift
gravitationally bound
gravity
gravity wave
guide star (GS)
GYRE
habitability
HARPS-N
Hayashi track
HCI
HD 114762
HD 189733 b
heliocentric system
heliosphere
helium (He)
helium runaway
helium star
Henyey track
high-velocity star
HII region (HII)
Hill radius
Hill stability
Holmberg radius (RH)
Honda-like star
horizontal branch (HB)
horizontal coordinate system
host star
HR 8799
Hubble Ultra-Deep Field (HUDF)
hydrostatic equilibrium
hypercompact stellar system (HCSS)
hypervelocity star (HVS)
ICRF
ideal gas law
imaging spectrometer
inside-out growth
instability strip
International Celestial Reference System (ICRS)
interplanetary medium (IPM)
ionized carbon fine structure line ([CII])
iron (Fe)
isochrone
J-region asymptotic giant branch (JAGB)
Jeans anisotropic modeling (JAM)
K-type star (K)
K2
kappa mechanism (κ-mechanism)
Kapteyn universe
Kelvin-Helmholtz mechanism (KH mechanism)
Kepler-186f
Kepler-79
Keplerian orbit
Kramers opacity law
Kuiper Belt (K Belt)
L-type star (L)
Landau damping
Lane-Emden equation
Large Altazimuth Telescope (BTA-6)
LB-1
Lick indices
Lindblad resonance
line blanketing
line broadening
lithium depletion boundary (LDB)
Local Group (LG)
long gamma-ray burst (LGRB)
low mass star (LMS)
luminosity (L)
luminosity class
luminosity density
luminous red nova (LRN)
Luyten Half-second Catalog (LHS)
Luyten Two-Tenths Arcsecond Catalog (LTT)
Lyapunov time
Lyman break (LB)
Lyman-Werner photon
Lyot coronagraph (CLC)
Lyot stop
M-sigma relation
M-type star (M)
Magellanic Catalogue of Stars (MACS)
Magellanic Clouds Photometric Survey (MCPS)
magnetic field
magnetorotational supernova (MR-sn)
magnitude
main sequence fitting
main sequence star (MS)
main-sequence lifetime (MS lifetime)
MaNGA Stellar Library (MaStar)
MARVEL
MASCARA
mass fraction
mass-radius relation
mass-to-light ratio (M/L)
meridian
MESA
Messier Catalog (M)
metallic hydrogen
metallicity (Z)
methylidyne (CH)
Milky Way chemical evolution
modified Newtonian dynamics (MOND)
moment of inertia factor
MOST
multiplicity fraction
MUSCLES
Narrabri Stellar Intensity Interferometer (NSII)
natural astronomical telescopes
neon burning
neutral atomic hydrogen (HI)
neutrons from carbon-13
New Catalogue of Suspected Variable Stars (NSV)
NGC 1866
north polar sequence (NPS)
nova (N)
nuclear statistical equilibrium (NSE)
number density (n)
O-type star (O)
O5 spectral type (O5)
OB association
OH/IR source
Olbers' paradox
Oort Cloud
Oort constants
open cluster (OC)
optical depth (τ)
Orion Molecular Cloud Complex
OSO 8
pair-instability supernova (PISN)
Palomar-Green Survey (PG)
Palomar-Haro-Luyten Catalog (PHL)
partial ionization zone
phase curve
PHAT
PHOENIX stellar model
phosphorus (P)
photometric system
planet structure
planetary mass object (PMO)
planetary nebula (PN)
plasma astrophysics
Pleiades (M45)
point-spread function (PSF)
polarimetry
polarization
position angle (PA)
post-AGB star (pAGB)
post-main-sequence star
power law
pre-main-sequence star (PMS)
precession
presolar grain
Press-Schechter formalism
primary
protoplanetary disk (PPD)
protostar
pseudobulge
pulsar (PSR)
pulsating star
r-process
Radcliffe Observatory Magellanic Clouds Catalogue (RMC)
radial velocity method
radial-drift barrier
radiation hydrodynamics (RHD)
radiation zone
radiative transfer code (RT code)
radio star
RAMBO
random walk
rare designator prefixes
red clump (RC)
red dwarf
red giant
red-giant branch (RGB)
reddening
redshift (z)
reference star differential imaging (RDI)
reflection nebula
refractive interstellar scintillation (RISS)
Rho Ophiuchi Cloud Complex
Rosseland mean opacity
rotation period
S-type star (S)
SAO Star Catalog
scale height (H)
Schönberg-Chandrasekhar limit
secondary eclipse
seismic waves
shell galaxy
shell star (sh)
sidereal
signal-to-noise ratio (SNR)
signatures of formation
Sirius
SkyMapper Southern Survey (SMSS)
slitless spectrograph
Sloan Digital Sky Survey (SDSS)
slowly-pulsating B-star (SPB)
SMSS J2003-1142
solar day
solar flare
solar mass (MSun)
solar physics
solar system
solar time
solid angle (Ω)
sound speed
Southern Stellar Stream Spectroscopic Survey (S5)
specific heat
spectral class
spectral line
spectral temperature
spectral type
spectroscopic binary (SB)
spectrum binary
SPECULOOS
spheroid
spiral arm
Spitzer Extended Deep Survey (SEDS)
standard candle
star cloud
star formation (SF)
star formation feedback
star formation rate (SFR)
star system
starburst galaxy
Stardust
STARFORGE
stellar age determination
stellar association
stellar astronomy
stellar birth rate function
stellar core
stellar demographics
stellar encounter
stellar flare
stellar model atmosphere
stellar population
stellar population synthesis (SPS)
stellar population synthesis code
stellar wind
Strömgren photometric system
Strömgren sphere
stripped star
subdwarf (sd)
subgiant
subgrid-scale physics
substellar object
substellar point
sulfur (S)
supergiant
superluminous supernova (SLSN)
supermassive star (SMS)
supernova (SN)
supernova impostor
supernova light curve (SN light curve)
supernova progenitor
supernova remnant (SNR)
surface brightness fluctuation (SBF)
surface density (Σ)
surface gravity (g)
survey-based designator
T association
T Tauri
T-type star (T)
Taurus-Auriga Complex (Tau-Aur Complex)
technetium star
telluric star
thermal pulse (TP)
thin disk
Thomson scattering
Thorne-Żytkow object (TZO)
tidal force
tidal tail
timescale (t)
Tokyo Photoelectric Meridian Circle
Toomre Q parameter (Q)
traditional approximation of rotation (TAR)
transit telescope
Transiting Exoplanet Survey Satellite (TESS)
transiting planet
Trapezium Cluster
TRAPPIST-1
Triangulum Galaxy (M33)
TSUNAMI­
turbulence
turn-off point (TO)
TW Hydrae (TW Hya)
TW Hydrae association (TWA)
twinkling
UBV photometric system
ultracool dwarf
ultraluminous X-ray source (ULX)
variable star
Vega
Vega system
velocity dispersion (σ)
visible light
visual binary
void
VY Canis Majoris (VY CMa)
W51
water-ice planet
weak interaction
weak-line star
Wesenheit function
white dwarf (WD)
Wien's displacement law
WISE 0855-0714 (W0855)
Wolf-Rayet star
X-ray luminosity function (XLF)
Y-type star (Y)
Yale Observatory Zone Catalog (YZ)
young stellar object (YSO)
Zanstra method
ZTF J1539+5027
[α/Fe] versus [Fe/H] diagram

Index