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Coordinates: Sky map 16h 19m 55.07s, −15° 38′ 24.8″
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dist_pc=2,800<ref name="par">{{cite journal | author = Bradshaw, C.F.; Fomalont, E.B.; Geldzahler, B.J. | title = High-Resolution Parallax measurements of Scorpius X-1 | journal = The Astrophysical Journal | volume = 512 | issue = 2 | pages = L121–L124 | bibcode = 1999ApJ...512L.121B | doi = 10.1086/311889 | year = 1999 | postscript = .}}</ref> |
dist_pc=2,800<ref name="par">{{cite journal | author = Bradshaw, C.F.| author2 = Fomalont, E.B.| author3 = Geldzahler, B.J. | title = High-Resolution Parallax measurements of Scorpius X-1 | journal = The Astrophysical Journal | volume = 512 | issue = 2 | pages = L121–L124 | bibcode = 1999ApJ...512L.121B | doi = 10.1086/311889 | date = 1999 | postscript = .}}</ref> |
names= V818 Sco, [[H]] 1620-15, [[2RE]] J161955-153824, [[1XRS]] 16170-155, [[Ariel V SSI catalogue|2A]] 1616-155, [[INTEGRAL1]] 21, [[ROSAT catalog|RE]] J1619-153, [[RXTE catalog|XSS]] J16204-1536, [[Ariel V 3A catalog|3A]] 1617-155, [[INTREF]] 685, [[ROSAT catalog|RE]] J161956-153814, X Sco X-1, [[2EUVE]] J1619-15.6, [[KOHX]] 20, [[SBC7]] 569, [[EUVE]] J1619-15.6, 1M 1617-155, [[Second UHURU catalog|2U]] 1617-15, [[AAVSO]] 1614-15, 1H 1617-155, [[2MASS]] J16195506-1538250, [[Third UHURU catalog|3U]] 1617-15, [[H]] 1617-155, [[2RE]] J1619-153, [[Fourth UHURU catalog|4U]] 1617-15. }}
names= V818 Sco, [[H]] 1620-15, [[2RE]] J161955-153824, [[1XRS]] 16170-155, [[Ariel V SSI catalogue|2A]] 1616-155, [[INTEGRAL1]] 21, [[ROSAT catalog|RE]] J1619-153, [[RXTE catalog|XSS]] J16204-1536, [[Ariel V 3A catalog|3A]] 1617-155, [[INTREF]] 685, [[ROSAT catalog|RE]] J161956-153814, X Sco X-1, [[2EUVE]] J1619-15.6, [[KOHX]] 20, [[SBC7]] 569, [[EUVE]] J1619-15.6, 1M 1617-155, [[Second UHURU catalog|2U]] 1617-15, [[AAVSO]] 1614-15, 1H 1617-155, [[2MASS]] J16195506-1538250, [[Third UHURU catalog|3U]] 1617-15, [[H]] 1617-155, [[2RE]] J1619-153, [[Fourth UHURU catalog|4U]] 1617-15. }}


'''[[Scorpius]] X-1''' is an [[X-ray]] source located roughly 9000 [[light year]]s away in the constellation [[Scorpius (constellation)|Scorpius]]. Scorpius X-1 was the first extrasolar X-ray source discovered, and, aside from the [[Sun]], it is the strongest apparent source of X-rays in the [[sky]].<ref>{{Cite journal | doi=10.1103/PhysRevLett.9.439 | last=Giacconi | first=R. | last2=Gursky | first2=H. | last3=Paolini |first3=F.R. | last4=Rossi | first4=B.B. | title=Evidence for X-rays from sources outside the solar system | journal=Phys. Rev. Lett. | volume=9 | issue=11 | pages=439–443 | year=1962 | postscript=. | bibcode=1962PhRvL...9..439G}}</ref> The X-ray [[flux]] varies day-to-day, and is associated with an [[visible light|optically]] visible [[star]], V818 Scorpii, that has an [[apparent magnitude]] which fluctuates between 12-13.<ref name="shklovskii">{{cite book | author = Shklovskii, Iosif S. | title = Stars: Their Birth, Life, and Death | year = 1978 | publisher = W.H. Freeman | isbn = 978-0-7167-0024-1 | url = http://books.google.com/?id=exSFQgAACAAJ}}</ref>
'''[[Scorpius]] X-1''' is an [[X-ray]] source located roughly 9000 [[light year]]s away in the constellation [[Scorpius (constellation)|Scorpius]]. Scorpius X-1 was the first extrasolar X-ray source discovered, and, aside from the [[Sun]], it is the strongest apparent source of X-rays in the [[sky]].<ref>{{Cite journal | doi=10.1103/PhysRevLett.9.439 | last=Giacconi | first=R. | last2=Gursky | first2=H. | last3=Paolini |first3=F.R. | last4=Rossi | first4=B.B. | title=Evidence for X-rays from sources outside the solar system | journal=Phys. Rev. Lett. | volume=9 | issue=11 | pages=439–443 | date=1962 | postscript=. | bibcode=1962PhRvL...9..439G}}</ref> The X-ray [[flux]] varies day-to-day, and is associated with an [[visible light|optically]] visible [[star]], V818 Scorpii, that has an [[apparent magnitude]] which fluctuates between 12-13.<ref name="shklovskii">{{cite book | author = Shklovskii, Iosif S. | title = Stars: Their Birth, Life, and Death | date = 1978 | publisher = W.H. Freeman | isbn = 978-0-7167-0024-1 | url = http://books.google.com/?id=exSFQgAACAAJ}}</ref>


==Discovery and early study==
==Discovery and early study==
Line 30: Line 30:
"The instrumentation had been designed for an attempt to observe X-rays from the moon and was not equipped with collimation to restrict the field of view narrowly. As a result, the signal was very broad, and accurate definition of the size and position of the source was not possible. A similar experiment was repeated in October 1962 when the galactic center was below the horizon and the strong source was not present. A third attempt, in June 1963, verified the results of the June 1962 flight."<ref name=Bowyer/> The [[Galactic Center]] is < 20° [[Right ascension|RA]] and < 20° [[Declination|Dec]] from Sco X-1, the two X-ray sources are separated by ~20° of arc and may not have been resolvable in the June 1962 flight.<ref name=Bowyer/>
"The instrumentation had been designed for an attempt to observe X-rays from the moon and was not equipped with collimation to restrict the field of view narrowly. As a result, the signal was very broad, and accurate definition of the size and position of the source was not possible. A similar experiment was repeated in October 1962 when the galactic center was below the horizon and the strong source was not present. A third attempt, in June 1963, verified the results of the June 1962 flight."<ref name=Bowyer/> The [[Galactic Center]] is < 20° [[Right ascension|RA]] and < 20° [[Declination|Dec]] from Sco X-1, the two X-ray sources are separated by ~20° of arc and may not have been resolvable in the June 1962 flight.<ref name=Bowyer/>


Scorpius XR-1 has been observed at J1950 [[Right ascension|RA]] {{RA|16|15}} [[Declination|Dec]] {{Dec|-15.2}}.<ref name=Bowyer>{{cite journal |author=Bowyer S, Byram ET, Chubb TA, Friedman H |title=Observational results of X-ray astronomy |journal=Astronomical Observations from Space Vehicles, Proceedings from Symposium no. 23 held in Liege, Belgium, 17 to 20 August 1964. |month= |year=1965 |editor=Steinberg JL |publisher=International Astronomical Union |pages=227–39 |bibcode=1965IAUS...23..227B |postscript=. }}</ref>
Scorpius XR-1 has been observed at J1950 [[Right ascension|RA]] {{RA|16|15}} [[Declination|Dec]] {{Dec|-15.2}}.<ref name=Bowyer>{{cite journal |author=Bowyer S|author2= Byram ET|author3=Chubb TA|author4=Friedman H |title=Observational results of X-ray astronomy |journal=Astronomical Observations from Space Vehicles, Proceedings from Symposium no. 23 held in Liege, Belgium, 17 to 20 August 1964. |date=1965 |editor=Steinberg JL |publisher=International Astronomical Union |pages=227–39 |bibcode=1965IAUS...23..227B |postscript=. }}</ref>


In 1967 (before the discovery of [[pulsar]]s), [[Iosif Shklovsky]] examined X-ray and optical observations of Scorpius X-1 and correctly concluded that the radiation comes from a [[neutron star]] accreting matter from a companion.<ref>{{Cite journal | last=Shklovsky | first=I.S. | title=On the Nature of the Source of X-Ray Emission of SCO XR-1 | journal=Astrophys. J. | volume=148 | issue=1 | pages=L1–L4 | date=April 1967 | doi=10.1086/180001 | year=2004 | postscript=. | bibcode=1967ApJ...148L...1S}}</ref>
In 1967 (before the discovery of [[pulsar]]s), [[Iosif Shklovsky]] examined X-ray and optical observations of Scorpius X-1 and correctly concluded that the radiation comes from a [[neutron star]] accreting matter from a companion.<ref>{{Cite journal | last=Shklovsky | first=I.S. | title=On the Nature of the Source of X-Ray Emission of SCO XR-1 | journal=Astrophys. J. | volume=148 | issue=1 | pages=L1–L4 | date=April 1967 | doi=10.1086/180001 2004 | postscript=. | bibcode=1967ApJ...148L...1S}}</ref>


==Characteristics==
==Characteristics==
Its X-ray output is 2.3&times;10<sup>31</sup> [[Watt|W]], about 60,000 times the total luminosity of the Sun.<ref name="par" /> Scorpius X-1 shows regular variations of up to 1 [[apparent magnitude|magnitude]] in its intensity, with a period of around 18.9 hours. The source varies irregularly in optical [[wavelength]]s as well, but these changes are not correlated with the X-ray variations.<ref name="shklovskii" /> Scorpius X-1 itself is a [[neutron star]] whose intense gravity draws material off this companion into an [[accretion disk]], where it ultimately falls onto the surface, releasing a tremendous amount of energy. As this stellar material accelerates in Scorpius X-1's gravitational field, X-rays are emitted. The measured luminosity for Scorpius X-1 is consistent with a neutron star which is accreting matter at its [[Eddington limit]].<ref name ="par" />
Its X-ray output is 2.3&times;10<sup>31</sup> [[Watt|W]], about 60,000 times the total luminosity of the Sun.<ref name="par" /> Scorpius X-1 shows regular variations of up to 1 [[apparent magnitude|magnitude]] in its intensity, with a period of around 18.9 hours. The source varies irregularly in optical [[wavelength]]s as well, but these changes are not correlated with the X-ray variations.<ref name="shklovskii" /> Scorpius X-1 itself is a [[neutron star]] whose intense gravity draws material off this companion into an [[accretion disk]], where it ultimately falls onto the surface, releasing a tremendous amount of energy. As this stellar material accelerates in Scorpius X-1's gravitational field, X-rays are emitted. The measured luminosity for Scorpius X-1 is consistent with a neutron star which is accreting matter at its [[Eddington limit]].<ref name ="par" />


This system is classified as a [[low-mass X-ray binary]]; the neutron star is roughly 1.4 [[solar masses]], while the donor star is only 0.42 solar masses.<ref>{{cite journal | author = Steeghs, D.; Casares, J. | title = The Mass Donor of Scorpius X-1 Revealed | journal = The Astrophysical Journal | volume = 568 | issue = 1 | pages = 273–278 | year = 2002 | doi = 10.1086/339224 | bibcode = 2002ApJ...568..273S | postscript = .|arxiv = astro-ph/0107343 }}</ref> The two stars were probably not born together; recent research suggests that the binary may have been formed by a close encounter inside a [[globular cluster]].<ref>{{cite journal | author = Mirabel, I. F.; Rodrogues, I. | title = The origin of Scorpius X-1 | journal = Astronomy and Astrophysics | volume = 398 | issue = 3 | pages = L25–L28 | year = 2003 | doi = 10.1051/0004-6361:20021767 | bibcode =2003A&A...398L..25M | postscript = .|arxiv = astro-ph/0301580 }}</ref>
This system is classified as a [[low-mass X-ray binary]]; the neutron star is roughly 1.4 [[solar masses]], while the donor star is only 0.42 solar masses.<ref>{{cite journal | author = Steeghs, D.| author2 = Casares, J. | title = The Mass Donor of Scorpius X-1 Revealed | journal = The Astrophysical Journal | volume = 568 | issue = 1 | pages = 273–278 | date = 2002 | doi = 10.1086/339224 | bibcode = 2002ApJ...568..273S | postscript = .|arxiv = astro-ph/0107343 }}</ref> The two stars were probably not born together; recent research suggests that the binary may have been formed by a close encounter inside a [[globular cluster]].<ref>{{cite journal | author = Mirabel, I. F.| author2 = Rodrogues, I. | title = The origin of Scorpius X-1 | journal = Astronomy and Astrophysics | volume = 398 | issue = 3 | pages = L25–L28 | date = 2003 | doi = 10.1051/0004-6361:20021767 | bibcode =2003A&A...398L..25M | postscript = .|arxiv = astro-ph/0301580 }}</ref>


==See also==
==See also==

Revision as of 19:30, 9 March 2015

V818 Sco or Scorpius X-1
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Scorpius
Right ascension 16h 19m 55.07s[1]
Declination -15° 38' 24.8"[1]
Apparent magnitude (V) 12.2[1]
Distance9,000 ly
(2,800[2] pc)
Other designations
V818 Sco, H 1620-15, 2RE J161955-153824, 1XRS 16170-155, 2A 1616-155, INTEGRAL1 21, RE J1619-153, XSS J16204-1536, 3A 1617-155, INTREF 685, RE J161956-153814, X Sco X-1, 2EUVE J1619-15.6, KOHX 20, SBC7 569, EUVE J1619-15.6, 1M 1617-155, 2U 1617-15, AAVSO 1614-15, 1H 1617-155, 2MASS J16195506-1538250, 3U 1617-15, H 1617-155, 2RE J1619-153, 4U 1617-15.

Scorpius X-1 is an X-ray source located roughly 9000 light years away in the constellation Scorpius. Scorpius X-1 was the first extrasolar X-ray source discovered, and, aside from the Sun, it is the strongest apparent source of X-rays in the sky.[3] The X-ray flux varies day-to-day, and is associated with an optically visible star, V818 Scorpii, that has an apparent magnitude which fluctuates between 12-13.[4]

Discovery and early study

The possible existence of soft x-rays was first proposed by Bruno Rossi, MIT Professor and Board Chairman of [American Science and Engineering] in [Cambridge, Massachusetts]to Martin Annis, President of AS&E. Following his urging, the company obtained a contract from the United States Air Force to explore the lunar surface prior to the launch of astronauts to the moon, and incidentally to perhaps see galactic sources of x-rays.

Subsequently, Scorpius X-1 was discovered in 1962 by a team, under Riccardo Giacconi, who launched an Aerobee 150 sounding rocket carrying a highly sensitive soft X-ray detector designed by Frank Paolini. The rocket trajectory was slightly off course but still detected a significant emission of soft x-rays that were not coming from the moon. Thus fortuitously, and as first pointed out by Frank Paolini, Scorpius X-1 became the first X-ray source discovered outside the Solar System. The angular resolution of the detector did not initially allow the position of Scorpius X-1 to be accurately determined. This led to suggestions that the source might be located near the Galactic center, but it was eventually realized that it lies in the constellation Scorpius.[4] As the first discovered X-ray source in Scorpius, it received the designation Scorpius X-1.

The Aerobee 150 rocket launched on June 12, 1962, detected the first X-rays from another celestial source (Scorpius X-1) at J1950 RA 16h 15m Dec −15.2°.[5] Sco X-1 is a LMXB in which the visual counterpart is V818 Scorpii.

Although the above reference indicates the rocket launch was on June 12, 1962, other sources indicate the actual launch was at 06:59:00 UTC on June 19, 1962.[6][7]

Historical footnote: "The instrumentation had been designed for an attempt to observe X-rays from the moon and was not equipped with collimation to restrict the field of view narrowly. As a result, the signal was very broad, and accurate definition of the size and position of the source was not possible. A similar experiment was repeated in October 1962 when the galactic center was below the horizon and the strong source was not present. A third attempt, in June 1963, verified the results of the June 1962 flight."[8] The Galactic Center is < 20° RA and < 20° Dec from Sco X-1, the two X-ray sources are separated by ~20° of arc and may not have been resolvable in the June 1962 flight.[8]

Scorpius XR-1 has been observed at J1950 RA 16h 15m Dec −15.2°.[8]

In 1967 (before the discovery of pulsars), Iosif Shklovsky examined X-ray and optical observations of Scorpius X-1 and correctly concluded that the radiation comes from a neutron star accreting matter from a companion.[9]

Characteristics

Its X-ray output is 2.3×1031 W, about 60,000 times the total luminosity of the Sun.[2] Scorpius X-1 shows regular variations of up to 1 magnitude in its intensity, with a period of around 18.9 hours. The source varies irregularly in optical wavelengths as well, but these changes are not correlated with the X-ray variations.[4] Scorpius X-1 itself is a neutron star whose intense gravity draws material off this companion into an accretion disk, where it ultimately falls onto the surface, releasing a tremendous amount of energy. As this stellar material accelerates in Scorpius X-1's gravitational field, X-rays are emitted. The measured luminosity for Scorpius X-1 is consistent with a neutron star which is accreting matter at its Eddington limit.[2]

This system is classified as a low-mass X-ray binary; the neutron star is roughly 1.4 solar masses, while the donor star is only 0.42 solar masses.[10] The two stars were probably not born together; recent research suggests that the binary may have been formed by a close encounter inside a globular cluster.[11]

See also

References

  1. ^ a b c Staff (March 3, 2003). "V* V1357 Cyg -- High Mass X-ray Binary". Centre de Données astronomiques de Strasbourg. Retrieved 2009-12-21.
  2. ^ a b c Bradshaw, C.F.; Fomalont, E.B.; Geldzahler, B.J. (1999). "High-Resolution Parallax measurements of Scorpius X-1". The Astrophysical Journal. 512 (2): L121–L124. Bibcode:1999ApJ...512L.121B. doi:10.1086/311889.{{cite journal}}: CS1 maint: postscript (link)
  3. ^ Giacconi, R.; Gursky, H.; Paolini, F.R.; Rossi, B.B. (1962). "Evidence for X-rays from sources outside the solar system". Phys. Rev. Lett. 9 (11): 439–443. Bibcode:1962PhRvL...9..439G. doi:10.1103/PhysRevLett.9.439.{{cite journal}}: CS1 maint: postscript (link)
  4. ^ a b c Shklovskii, Iosif S. (1978). Stars: Their Birth, Life, and Death. W.H. Freeman. ISBN 978-0-7167-0024-1.
  5. ^ Giacconi R (August 2003). "Nobel Lecture: The dawn of X-ray astronomy". Rev Mod Phys. 75 (3): 995–1010. Bibcode:2003RvMP...75..995G. doi:10.1103/RevModPhys.75.995.{{cite journal}}: CS1 maint: postscript (link)
  6. ^ Drake SA (September 2006). "A Brief History of High-Energy Astronomy: 1960 - 1964".
  7. ^ "Chronology - Quarter 2 1962".
  8. ^ a b c Bowyer S; Byram ET; Chubb TA; Friedman H (1965). Steinberg JL (ed.). "Observational results of X-ray astronomy". Astronomical Observations from Space Vehicles, Proceedings from Symposium no. 23 held in Liege, Belgium, 17 to 20 August 1964. International Astronomical Union: 227–39. Bibcode:1965IAUS...23..227B.{{cite journal}}: CS1 maint: postscript (link)
  9. ^ Shklovsky, I.S. (April 1967). "On the Nature of the Source of X-Ray Emission of SCO XR-1". Astrophys. J. 148 (1): L1–L4. Bibcode:1967ApJ...148L...1S. doi:10.1086/180001 2004. {{cite journal}}: Check |doi= value (help)CS1 maint: postscript (link)
  10. ^ Steeghs, D.; Casares, J. (2002). "The Mass Donor of Scorpius X-1 Revealed". The Astrophysical Journal. 568 (1): 273–278. arXiv:astro-ph/0107343. Bibcode:2002ApJ...568..273S. doi:10.1086/339224.{{cite journal}}: CS1 maint: postscript (link)
  11. ^ Mirabel, I. F.; Rodrogues, I. (2003). "The origin of Scorpius X-1". Astronomy and Astrophysics. 398 (3): L25–L28. arXiv:astro-ph/0301580. Bibcode:2003A&A...398L..25M. doi:10.1051/0004-6361:20021767.{{cite journal}}: CS1 maint: postscript (link)


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