An Eccentric Binary Millisecond Pulsar in the Galactic Plane
David J. Champion,1,2*
Scott M. Ransom,3
Patrick Lazarus,1
Fernando Camilo,4
Cees Bassa,1
Victoria M. Kaspi,1
David J. Nice,5
Paulo C. C. Freire,6
Ingrid H. Stairs,7
Joeri van Leeuwen,8
Ben W. Stappers,9
James M. Cordes,10
Jason W. T. Hessels,11
Duncan R. Lorimer,12
Zaven Arzoumanian,13
Don C. Backer,8
N. D. Ramesh Bhat,14
Shami Chatterjee,15
Ismaël Cognard,16
Julia S. Deneva,10
Claude-André Faucher-Giguère,17
Bryan M. Gaensler,15
JinLin Han,18
Fredrick A. Jenet,19
Laura Kasian,7
Vlad I. Kondratiev,12
Michael Kramer,9
Joseph Lazio,20
Maura A. McLaughlin,12
Arun Venkataraman,6
Wouter Vlemmings21
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 (
) 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 , an unusually high value.
1 Department of Physics, McGill University, Montreal, QC H3A 2T8, Canada.
2 Australia Telescope National Facility (ATNF), Commonwealth Scientific and Industrial Research Organisation, Post Office Box 76, Epping NSW 1710, Australia.
3 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA.
4 Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027, USA.
5 Physics Department, Bryn Mawr College, Bryn Mawr, PA 19010, USA.
6 National Astronomy and Ionosphere Center (NAIC), Arecibo Observatory, HC03 Box 53995, Arecibo, PR 00612, USA.
7 Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada.
8 Astronomy Department, 441 Campbell Hall, University of California at Berkeley, Berkeley, CA 94720, USA.
9 Jodrell Bank Observatory, Manchester University, Macclesfield, Cheshire SK11 9DL, UK.
10 Astronomy Department, Cornell University, Ithaca, NY 14853, USA.
11 Astronomical Institute "Anton Pannekoek," University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands.
12 Department of Physics, West Virginia University, Morgantown, WV 26506, USA.
13 Center for Research and Exploration in Space Science and Technology, and X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA.
14 Swinburne University of Technology, Post Office Box 218, Hawthorn, Victoria 3122, Australia.
15 School of Physics, The University of Sydney, NSW 2006 Australia.
16 LaboratoiredePhysiqueet Chimiedel'Environnement, Centre National de la Recherche Scientifique, UMR 6115 3A, Avenue de la Recherche Scientifique, F-45071 Orleans Cedex 2, France.
17 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-10, Cambridge, MA 02138, USA.
18 National Astronomical Observatories, Chinese Academy of Sciences, Jia-20 DaTun Road, Chaoyang District, Beijing 100012, China.
19 Center for Gravitational Wave Astronomy, University of Texas, Brownsville, TX 78520, USA.
20 Naval Research Laboratory (NRL), 4555 Overlook Avenue, SW, Washington, DC 20375, USA.
21 Argelander-Institut für Astronomie, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany.
* To whom correspondence should be addressed. E-mail: David.Champion{at}atnf.csiro.au
