(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.
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, typically H-alpha, is often useful to determine
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 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 is often used with the broader meaning.
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 mean radio source).
|Prefix||Example|| || |
|QSO||QSO B1957+405||general prefix|| |
|QSR||QSR J1819+3845||general for "radio-loud quasar"|| |
|Quasar||Quasar J192748.6+735802||general prefix|| |
Referenced by pages:
Balmer series (H)
Blandford-Znajek mechanism (BZ process)
Baryon Oscillation Spectroscopic Survey (BOSS)
Canada-France High-z Quasar Survey (CFHQS)
Cygnus A (3C 405)
direct collapse black hole (DCBH)
deep field (DF)
Dark Energy Spectroscopic Instrument (DESI)
epoch of reionization (EOR)
star formation feedback
gravitational potential energy
Hamburg/ESO Survey (HE)
high-energy astrophysics (HEA)
hyperluminous infrared galaxy (HLIRG)
Hamburg Schmidt Survey (HS)
International Celestial Reference System (ICRS)
Large Bright QSO Survey (LBQS)
luminous infrared galaxy (LIRG)
large quasar group (LQG)
NASA/IPAC Extragalactic Database (NED)
Palomar Four-filter Survey (PC)
Pico dos Dias Survey (PDS)
Palomar-Green Survey (PG)
rare designator prefixes
radio galaxy (RG)
Second Byurakan Survey (SBS)
Sloan Digital Sky Survey (SDSS)
Seyfert galaxy (Sy)
supermassive black hole (SMBH)
Tonantzintla Surveys (Ton)
2dF Galaxy Redshift Survey (2dFGRS)
2dF-SDSS LRG and QSO survey (2SLAQ)
James Webb Space Telescope (JWST)