PSR J1903+0327

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PSR J1903+0327 is a millisecond pulsar in a highly eccentric binary orbit[1]. The pulsar was discovered in an ongoing L-band (1.4 GHz) survey[2] with the 305 m diameter Arecibo radio telescope. The pulse period is 2.15 ms. Analysis of the pulse timing residuals shows a binary orbit with a period of 95.17 days, and a high eccentricity, e = 0.437. The mass of the companion is ~1 solar mass, while the pulsar mass is unusually large, ~1.74 solar masses. A possible near-infrared companion, KS = 18 (2.22µ), is observed in Gemini North images at its radio position.

Popular theories for the formation of binary millisecond pulsars require mass transfer onto the rotating neutron star from a white dwarf companion in order to spin it up to periods less than about 10 ms, which process is expected to be accompanied by strong tidal forces, producing a highly circular orbit. PSR J1903+0327 appears to require a different formation mechanism. Its large mass may also constrain the equation of state for nuclear matter at high densities.

[edit] References

  1. ^ Champion et al, Science , 6 June 2008: Vol. 320. no. 5881, pp. 1309 - 1312 DOI: 10.1126/science.1157580
  2. ^ J. M. Cordes et al., Astrophys. J. 637, 446 (2006).
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