title: An eccentric binary millisecond pulsar in the galactic plane.
abstract: Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 milliseconds in a highly eccentric (e = 0.44) 95-day orbit around a solar mass (M(middle dot in circle)) companion. Infrared observations identify a possible main-sequence companion star. Conventional binary stellar evolution models predict neither large orbital eccentricities nor main-sequence companions around millisecond pulsars. Alternative formation scenarios involve recycling a neutron star in a globular cluster, then ejecting it into the Galactic disk, or membership in a hierarchical triple system. A relativistic analysis of timing observations of the pulsar finds its mass to be 1.74 +/- 0.04 M solar symbol, an unusually high value.
authors.affiliation: Department of Physics, McGill University, Montreal, QC H3A 2T8, Canada. David.Champion@atnf.csiro.au
authors.forename: David J
authors.initials: DJ
authors.lastname: Champion
authors.forename: Scott M
authors.initials: SM
authors.lastname: Ransom
authors.forename: Patrick
authors.initials: P
authors.lastname: Lazarus
authors.forename: Fernando
authors.initials: F
authors.lastname: Camilo
authors.forename: Cees
authors.initials: C
authors.lastname: Bassa
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Kaspi
authors.forename: David J
authors.initials: DJ
authors.lastname: Nice
authors.forename: Paulo C C
authors.initials: PC
authors.lastname: Freire
authors.forename: Ingrid H
authors.initials: IH
authors.lastname: Stairs
authors.forename: Joeri
authors.initials: J
authors.lastname: van Leeuwen
authors.forename: Ben W
authors.initials: BW
authors.lastname: Stappers
authors.forename: James M
authors.initials: JM
authors.lastname: Cordes
authors.forename: Jason W T
authors.initials: JW
authors.lastname: Hessels
authors.forename: Duncan R
authors.initials: DR
authors.lastname: Lorimer
authors.forename: Zaven
authors.initials: Z
authors.lastname: Arzoumanian
authors.forename: Don C
authors.initials: DC
authors.lastname: Backer
authors.forename: N D Ramesh
authors.initials: ND
authors.lastname: Bhat
authors.forename: Shami
authors.initials: S
authors.lastname: Chatterjee
authors.forename: Ismaël
authors.initials: I
authors.lastname: Cognard
authors.forename: Julia S
authors.initials: JS
authors.lastname: Deneva
authors.forename: Claude-André
authors.initials: CA
authors.lastname: Faucher-Giguère
authors.forename: Bryan M
authors.initials: BM
authors.lastname: Gaensler
authors.forename: Jinlin
authors.initials: J
authors.lastname: Han
authors.forename: Fredrick A
authors.initials: FA
authors.lastname: Jenet
authors.forename: Laura
authors.initials: L
authors.lastname: Kasian
authors.forename: Vlad I
authors.initials: VI
authors.lastname: Kondratiev
authors.forename: Michael
authors.initials: M
authors.lastname: Kramer
authors.forename: Joseph
authors.initials: J
authors.lastname: Lazio
authors.forename: Maura A
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authors.lastname: McLaughlin
authors.forename: Arun
authors.initials: A
authors.lastname: Venkataraman
authors.forename: Wouter
authors.initials: W
authors.lastname: Vlemmings