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:
51 Eridani b
51 Pegasi b (51 Peg b)
A-LIST
A-type star (A)
AB system
absolute magnitude (M)
adaptive mesh refinement (AMR)
adaptive optics (AO)
age-velocity-dispersion relation (AVR)
Airy disk
Alpha Centauri (α Centauri)
alpha element
alpha-enhanced
aluminum (Al)
angular distance
arcsecond (arcsec)
Arcturus
asteroseismology
Astrographic Catalog (AC)
astrometric binary
astrometry
astronomical catalog
astronomical object
astronomical symbol
asymptotic giant branch (AGB)
atmosphere
B-type star (B)
Balmer jump (BJ)
barium star (Ba star)
BATC
Be star
Betelgeuse
binary companion
binary star
Birkhoff's theorem
blind survey
blue horizontal branch (BHB)
blue loop (BL)
bolometric correction
bolometric magnitude (Mbol)
Bonner Durchmusterung Catalog (BD)
bow shock
brown dwarf (BD)
Bruce Proper Motion Survey (BPM)
BT-Settl
bulge
Canada-France-Hawaii Telescope (CFHT)
carbon star (C)
Catalog of Azzopardi & Vigneau (AzV)
celestial coordinate system
chemical equilibrium (CE)
chemical tagging
chemically peculiar star (CP star)
chromatic aberration
circumbinary planet
circumstellar disk
circumstellar envelope (CSE)
cold gas
collapsar
color index
color-color diagram (CCD)
column density
compact object (CO)
comparator
computational astrophysics
constellation
cooling function
Danjon astrolabe
DAOPHOT
dark age
dark galaxy
dark matter filament
Dartmouth Stellar Evolution Database (DSED)
dense core
DISORT
double star
Dynamical Analysis of Nearby Clusters (DANCe)
dynamical friction
eclipse mapping
eclipsing binary (E)
Eddington approximation
Eddington luminosity
electron capture
emission nebula
emission-line star
epicycle
epicyclic frequency
epoch
evaporating gas globule (EGG)
event horizon (EH)
evolutionary track
exotic star
F-type star (F)
FGK star
field star
fixed star
flux-weighted gravity-luminosity relationship (FGLR)
FORNAX
G-type star (G)
GaiaHub
galactic bulge
galactic center
galactic plane
galaxy bias
galaxy main sequence
Gamow peak
General Catalogue of Trigonometric Parallaxes (GCTP)
giant star
Gliese-Jahreiss Catalog (GJ)
gravitational potential energy
gravitational redshift
gravity wave
guide star (GS)
GYRE
habitability
HARPS-N
HCI
HD 114762
heliocentric system
heliosphere
helium runaway
helium star
high-velocity star
HII region (HII)
Hill radius
Honda-like star
horizontal branch (HB)
horizontal coordinate system
host star
hydrostatic equilibrium
hypercompact stellar system (HCSS)
hypervelocity star (HVS)
ICRF
ideal gas law
imaging spectrometer
inside-out growth
instability strip
isochrone
Jeans anisotropic modeling (JAM)
K-type star (K)
K2
kappa mechanism (κ-mechanism)
Kepler-186f
Kepler-79
Kramers opacity law
Kuiper Belt (K Belt)
L-type star (L)
Lane-Emden equation
Large Altazimuth Telescope (BTA-6)
LB-1
line blanketing
line broadening
Local Group (LG)
long gamma-ray burst (LGRB)
low mass star (LMS)
luminosity (L)
luminosity class
luminosity density
Lyapunov time
Lyman-Werner photon
Lyot stop
M-sigma relation
M-type star (M)
Magellanic Catalogue of Stars (MACS)
magnitude
main sequence star (MS)
main-sequence lifetime (MS lifetime)
MaNGA Stellar Library (MaStar)
mass-radius relation
meridian
metallic hydrogen
metallicity (Z)
methylidyne (CH)
Milky Way chemical evolution
modified Newtonian dynamics (MOND)
moment of inertia factor
MUSCLES
Narrabri Stellar Intensity Interferometer (NSII)
neutral atomic hydrogen (HI)
neutrons from carbon-13
New Catalogue of Suspected Variable Stars (NSV)
NGC 1866
north polar sequence (NPS)
nova (N)
number density (n)
O-type star (O)
O5 spectral type (O5)
OB association
Olbers' paradox
Oort Cloud
Oort constants
open cluster (OC)
Orion Molecular Cloud Complex
pair-instability supernova (PISN)
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)
Pleiades (M45)
point-spread function (PSF)
polarimetry
position angle (PA)
post-main-sequence star
pre-main-sequence star (PMS)
precession
presolar grain
Press-Schechter formalism
primary
protoplanetary disk (PPD)
protostar
pseudobulge
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
Rho Ophiuchi Cloud Complex
S-type star (S)
SAO Star Catalog
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
slowly-pulsating B-star (SPB)
SMSS J2003-1142
solar day
solar flare
solar system
solar time
spectral type
spectroscopic binary (SB)
spectrum binary
SPECULOOS
Spitzer Extended Deep Survey (SEDS)
star formation (SF)
star system
starburst galaxy
Stardust
STARFORGE
stellar age determination
stellar association
stellar astronomy
stellar birth rate function
stellar encounter
stellar model atmosphere
stellar population
stellar population synthesis (SPS)
stellar population synthesis code
stellar wind
stripped star
subdwarf (sd)
subgiant
subgrid-scale physics
substellar object
sulfur (S)
supergiant
supermassive star (SMS)
supernova (SN)
supernova impostor
supernova light curve (SN light curve)
supernova progenitor
supernova remnant (SNR)
survey-based designator
T Tauri
T-type star (T)
Taurus-Auriga Complex (Tau-Aur Complex)
technetium star
telluric star
thermal pulse (TP)
Thorne-Żytkow object (TZO)
traditional approximation of rotation (TAR)
transit telescope
transiting planet
Trapezium Cluster
TRAPPIST-1
Triangulum Galaxy (M33)
TSUNAMI­
turbulence
turn-off point (TO)
ultracool dwarf
ultraluminous X-ray source (ULX)
variable star
Vega
visible light
visual binary
void
W51
weak interaction
weak-line star
Wesenheit function
white dwarf (WD)
Wien's displacement law
WISE 0855-0714 (W0855)
Wolf-Rayet star
Y-type star (Y)
young stellar object (YSO)
Zanstra method
ZTF J1539+5027

Index