CXOU J164710.2-455216

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CXOU J164710.2-455216
Artist’s impression of the magnetar in the star cluster Westerlund 1.jpg
Artist's impression of CXOU J164710.2-455216
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ara
Right ascension 16h 47m 10.20s
Declination −45° 52′ 16.8″
Evolutionary stage Neutron star
Apparent magnitude () >18.5[1]
Distance approx. 16000 ly
(approx. 5000 pc)
Rotation 10.6105(1)s
Other designations
CXOU J164710.20-455217, CXOU J164710.2-455217
Database references

CXOU J164710.2-455216 is an anomalous X-ray pulsar in the massive galactic open cluster Westerlund 1. It is the brightest X-ray source in the cluster, and was discovered in 2005 in observations made by the Chandra X-ray observatory.[1][2] The Westerlund 1 cluster is believed to have formed in a single burst of star formation,[3] implying that the progenitor star must have had a mass in excess of 40 solar masses. The fact that a neutron star was formed instead of a black hole implies that more than 95% of the star's original mass must have been lost before or during the supernova that produced the magnetar.[4][5]

On 21 September 2006 the Swift satellite detected a 20ms soft Gamma-ray burst in Westerlund 1. Fortuitously, XMM-Newton observations had been made four days earlier, and repeat observations 1.5 days after the burst revealed the magnetar to be the source of the burst, with the X-ray luminosity increasing by a factor of 100 during the outburst.[6]


  1. ^ a b A Neutron Star with a Massive Progenitor in Westerlund 1, Muno et al. (2006)
  2. ^ Westerlund 1: Neutron Star Discovered Where a Black Hole Was Expected
  3. ^ On the massive stellar population of the super star cluster Westerlund 1, Clark et al. (2005)
  4. ^ Magnetar Formation Mystery Solved, eso1415 - Science Release (14 May 2014)
  5. ^ Wood, Chris. "Very Large Telescope solves magnetar mystery" GizMag, 14 May 2014. Accessed: 18 May 2014.
  6. ^ Exciting the magnetosphere of the magnetar CXOU J164710.2-455216 in Westerlund 1, Muno et al. (2007)

Coordinates: Sky map 16h 47m 10.20s, −45° 52′ 16.8″