Editing Microquasar

{{Short description|Nearby miniature analogue of a quasar}}
[[Image:Ss433 art big.gif|thumb|Artist's impression of the microquasar [[SS 433]]]]
A '''microquasar''', a smaller version of a [[quasar]], is a compact region surrounding a [[stellar black hole]] with a mass several times that of its [[Binary star#Cataclysmic variables and X-ray binaries|companion star]], observable in sufficient details, in [[Milky Way|our own]] or nearby galaxy.<ref name="a">{{cite web|title=First Microquasar Found Beyond Our Milky Way|url=http://www.nrao.edu/pr/2012/microquasar/|website=www.nrao.edu|accessdate=19 January 2017}}</ref> The matter being pulled from the companion [[star]] forms an [[accretion disk]] around the [[black hole]]. This accretion disk may become so hot, due to friction, that it begins to emit [[X-ray]]s.<ref name="b"/> The disk also projects narrow streams or "[[Astrophysical jet|jets]]" of subatomic particles at near-[[Speed of light|light speed]], generating a strong [[radio wave]] emission.

==Overview==
In 1979, [[SS 433]], in our own galaxy, became the first microquasar to be discovered, when Margon et al. observed its relativistic jets.<ref name="Margon">{{cite web |last1=Margon |first1=Bruce |title=Relativistic Jets in SS 433 |url=https://www.science.org/doi/abs/10.1126/science.215.4530.247 |website=science.org |publisher=Science, Vol 215, Issue 4530, pp. 247-252 |access-date=15 October 2024 |date=15 January 1982}}</ref> It was thought to be the most exotic case until similar objects such as [[GRS 1915+105]] were confirmed in 1994.<ref name="b">{{cite web|title=Microquasars in the Milky Way|url=https://www.nrao.edu/pr/2000/vla20/background/superlum/|website=www.nrao.edu|accessdate=19 January 2017}}</ref>

In some cases, blobs or "knots" of brighter [[plasma (physics)|plasma]] within the jets appear to be traveling faster than the speed of light, an [[optical illusion]] called [[superluminal motion]] which is caused by sub-light-speed particles being projected at a small angle relative to the observer.<ref name="b"/>

The 1996 [[Bruno Rossi Prize]] of the American Astronomical Society was awarded to Felix Mirabel and Luis Rodríguez for their discovery of the [[superluminal motion]] of radio knots in GRS 1915+105, as well as the discovery of double-sided radio jets from galactic sources [[Great Annihilator|1E1740.7-2942]] and [[GRS 1758-258]].<ref name="prizelist">{{cite web|title=HEAD AAS Rossi Prize Winners|url=https://head.aas.org/rossi/rossi.recip.html#L|website=www.head.aas.org|accessdate=27 August 2017}}</ref><ref name="superluminal">{{cite journal |last1=Mirabel|first1=Felix|last2=Rodriguez|first2=Luis F.|date=1994|title=A superluminal source in the Galaxy|journal=Nature|volume=371|issue=6492|pages=46–48|doi=10.1038/371046a0|bibcode = 1994Natur.371...46M |s2cid=4347263}}</ref><ref name="gammasources">{{cite journal |last1=Mirabel|first1=Felix|date=1994|title=Multiwavelength approach to gamma-ray sources in the Galactic center region|journal=Astrophys. J. Suppl. Ser.|volume=92|pages=369–373|doi=10.1086/191980|bibcode = 1994ApJS...92..369M }}</ref>

Due to the smaller size of microquasars, many of the effects are scaled differently in relation to normal quasars. In quasars, the mean temperature of the [[accretion disk]] is several thousand degrees, while in a microquasar the mean temperature is several million degrees. The average size of the accretion disk of a quasar is {{convert|1|e9km2|e6mi2|abbr=off}}, whereas in microquasars the average size is only {{convert|1000|km2|abbr=on}}. Quasars can project jets up to several million [[light-year]]s, whereas microquasars can project them only a few light-years; however, the "knots" within the jets of microquasars can exhibit a [[proper motion]] (angular motion across the sky) on the order of a thousand times faster than that of knots within a quasar jet because observed microquasars (being within the [[Milky Way]] galaxy) are at typical distances on the order of kilo[[parsec]]s, rather than hundreds of megaparsecs to several gigaparsecs.<ref>{{cite web|title=Microquasars as sources of high energy phenomena -I.F. Mirabel|url=https://ned.ipac.caltech.edu/level5/Sept02/Mirabel/Mirabel1.html|website=ned.ipac.caltech.edu|accessdate=19 January 2017}}</ref>

==See also==
*[[List of microquasars]]

==References==
{{reflist}}

{{Black holes}}
{{Portal bar|Astronomy|Stars|Outer space}}

[[Category:Microquasars| ]]
[[Category:X-ray binaries|*]]
[[Category:Astronomical radio sources]]