Astrophysics (Index)About

quasar

(QSO, quasi-stellar object)
(distant, bright object that appears something like a star)

A quasar (from quasi-stellar object or QSO) is an object with the point-like appearance of a star, but with a redshift indicating a far greater distance than that of a visible individual star. First noticed in the 1960s, quasars are now identified to be active galactic nuclei (AGNs). Observed redshifts range from 0.05 to greater than 7, putting them in the range of 600 million to near 13 billion light-years' distant (and years old). The Balmer series spectral lines are often useful to determine their redshift, typically H-alpha. They appear bright enough that some quasars might equal the Sun's apparent brightness as seen from Earth at a distance of 30 light-years. However, they do not necessarily shine so brightly in all directions. Their strong light can be lensed by nearer objects and can be useful for studying the objects doing the lensing. As a very-distant-but-observable light source, their light is useful in studying material it passes through.

The term quasi-stellar source (or QSS or quasi-stellar radio source, also sometimes using the prefix QSR) refers to a quasar that is also a strong radio source. The terms radio loud quasar (RLQ) and radio quiet quasar (RQQ) are also used. In fact, the term quasar was originally coined for such radio sources (but now is often used with the above broader meaning), and the term quasi-stellar galaxy (QSG) formerly was used for radio-quiet quasars. (Note that in radio astronomy, the word source is typically assumed to specifically mean a radio source).

Another classification of quasars is between red quasars and blue quasars. The former are presumed to be within dusty galaxies, and the latter, those not so dusty, so the bluer light of the AGN is visible to us.


(stars,galaxies,AGN,object type,jets)
Further reading:
https://en.wikipedia.org/wiki/Quasar
https://ned.ipac.caltech.edu/level5/ESSAYS/Barthel/barthel.html
https://astronomy.swin.edu.au/cosmos/q/quasar
http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/quasar.html
https://dictionary.obspm.fr/index.php?formSearchTextfield=quasar&showAll=1
https://esahubble.org/wordbank/quasar/
PrefixExample  
QQ0051-279abbreviated general prefix
QSOQSO B1957+405general prefix
QSRQSR J1819+3845general for "radio-loud quasar"
QuasarQuasar J192748.6+735802general prefix

Referenced by pages:
2dF Galaxy Redshift Survey (2dFGRS)
2dF-SDSS LRG and QSO survey (2SLAQ)
3C 273
3C 279
3C 48
3C 9
accretion rate
active galaxy
AGN accretion
ALMACAL
astronomical catalog
Baldwin effect
Balmer jump (BJ)
Balmer series (H)
Baryon Oscillation Spectroscopic Survey (BOSS)
black hole (BH)
black hole mass function (BHMF)
Blandford-Znajek mechanism (BZ process)
blazar
Calán/Tololo Supernova Survey
Canada-France High-z Quasar Survey (CFHQS)
Catalogues of Fundamental Stars
celestial reference frame
cosmological redshift
Cygnus A (3C 405)
damped Lyman alpha absorber (DLA)
Dark Energy Spectroscopic Instrument (DESI)
dark matter (DM)
deep field (DF)
Deep Multicolor Survey (DMS)
deep survey
diffractive interstellar scintillation (DISS)
direct collapse black hole (DCBH)
Eddington luminosity
epoch of reionization (EOR)
extragalactic astronomy
FIRST
galactic coordinate system (GCS)
Giant Gemini GMOS survey (GGG survey)
gravitational lensing
gravitational potential energy
GRS 1915+105
Gunn-Peterson trough
Hamburg Schmidt Survey (HS)
Hamburg/ESO Survey (HE)
high-energy astrophysics (HEA)
hot DOG
Huge-LQG
hyperluminous infrared galaxy (HLIRG)
ICRF
intensity mapping (IM)
intergalactic dust
International Celestial Reference System (ICRS)
James Webb Space Telescope (JWST)
Kelvin-Helmholtz mechanism (KH mechanism)
Large Bright QSO Survey (LBQS)
large quasar group (LQG)
luminous infrared galaxy (LIRG)
Lyman alpha (Ly-α)
Lyman beta (Ly-β)
Lyman break (LB)
Lyman-alpha forest
microquasar
NASA/IPAC Extragalactic Database (NED)
Palomar high-redshift quasar surveys
Palomar-Green Survey (PG)
Penrose Compton scattering (PCS)
PG 1302-102
Pico dos Dias Survey (PDS)
primordial black hole (PBH)
proximity effect
radio galaxy (RG)
radio star
rare designator prefixes
relativistic beaming
retrograde accretion
Roma-BZCAT
Salpeter timescale
Second Byurakan Survey (SBS)
Seyfert galaxy (Sy)
sidereal
Sloan Digital Sky Survey (SDSS)
SMBH formation
Soltan argument
spectral signature
star formation feedback
supermassive black hole (SMBH)
supermassive star (SMS)
Tonantzintla Surveys (Ton)
TXS 0506+056
X-ray source
XQR-30

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