Circinus X-1

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Circinus X-1

X-ray image of Circinus X-1
Credit: Chandra X-ray Observatory
Observation data
J2000
Constellation Circinus
Right ascension 15h 20m 40.85s[1]
Declination −57° 10′ 00.1″[1]
Apparent magnitude (V) 21.40[2]
Characteristics
Spectral type B5–A0 I[3]
Variable type
HMXB[4]
Distance
31000+2600
−3300 ly
(9400+800
−1000[5] pc)
Semi-amplitude
(K1)
(primary)		25 ± 2 km/s
BR Cir, 2MASS J15204084-5710001[4]
Database references
SIMBADdata

Circinus X-1 is an X-ray binary star system that includes a neutron star. Observation of Circinus X-1 in July 2007 revealed the presence of X-ray jets normally found in black hole systems; it is the first of the sort to be discovered that displays this similarity to black holes. Circinus X-1 may be among the youngest X-ray binaries observed.

Location, distance

On June 14, 1969, an

Aerobee 150 rocket, launched from Natal, Rio Grande do Norte, Brazil, obtained X-ray data during a scan of the Norma-Lupus-Circinus region that detected a well-isolated source at ℓ = 321.4±0.9° b = -0.5±2° (galactic), RA 15h 14m Dec −57° 49′ within the constellation Circinus and referred to as Circinus XR-1 (Cir XR-1).[6]
The distance of Circinus X-1 was not well established, with a low estimate of 13,400 light years[7] and high estimate of 26,000 light years.[8]

On June 23, 2015, an article published on NASA's Chandra X-Ray Observatory's website, revealed that an international team of astronomers has succeeded in determining its distance from Earth with more precision - via a method of triangulation of X-ray light emitted by the star, echoing through stellar clouds and interstellar dust - as being about 30,700 light-years.[9]

X-ray source and age related to supernova remnant

A 16.6 day X-ray period was found by Kaluzienski et al.[10] The X-ray source is assumed to be a neutron star as part of a low-mass X-ray binary (LMXB), type-I X-ray burster.[11] The X-ray and radio nebulae surrounding Circinus X-1 have properties consistent with a young supernova remnant. This rare case of an X-ray binary apparently associated with a supernova remnant suggests the binary is very young on cosmic time scales, possibly less than 4600 years old.[12] An association of Circinus X-1 with a different nearby supernova remnant, G321.9-0.3, has been ruled out.[11]

X-ray light rings from a neutron star in Circinus X-1 (24 June 2015; Chandra X-ray Observatory).

Other spectral regions

The binary nature of Cir X-1 has been established.[13] The binary's radio component and a possible visual counterpart were identified by Whelan et al.[14] Its infrared counterpart was located and found to flare with a 16.6-day period by Glass.[15] A (heavily reddened) precise optical counterpart (now known as BR Cir) was identified by Moneti.[16]

References

  1. ^
    S2CID 115529446
    .
  2. S2CID 14673570
    .
  3. ^
    S2CID 7474465
    .
  4. ^ a b "V* BR Cir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 22 September 2017.
  5. S2CID 17657655
    .
  6. hdl:2060/19710026671
    .
  7. S2CID 18973228
    .
  8. ^ "Circinus X-1: Neutron Stars Join The Black Hole Jet Set". Harvard-Smithsonian Center for Astrophysics. Retrieved 5 December 2013.
  9. ^ "NASA's Chandra Captures X-Ray Echoes Pinpointing Distant Neutron Star". 23 June 2015. Retrieved 24 June 2015.
  10. doi:10.1086/182235
    .
  11. ^
    S2CID 18606269
    .
  12. S2CID 6064052
    .
  13. Bibcode:1973BAAS....5..395J
    .
  14. doi:10.1093/mnras/181.2.259
    .
  15. doi:10.1093/mnras/183.3.335
    .
  16. Bibcode:1992A&A...260L...7M
    .

External links

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