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The evolution and masses of the neutron star and donor star in the high mass X-ray binary OAO 1657−415†

  1. A. B. Mason1,*,
  2. J. S. Clark1,
  3. A. J. Norton1,
  4. P. A. Crowther2,
  5. T. M. Tauris3,4,
  6. N. Langer3,5,
  7. I. Negueruela6,
  8. P. Roche7,8

Article first published online: 5 MAR 2012

DOI: 10.1111/j.1365-2966.2012.20596.x

Issue

Monthly Notices of the Royal Astronomical Society

Monthly Notices of the Royal Astronomical Society

Volume 422, Issue 1, pages 199–206, May 2012

Additional Information

How to Cite

Mason, A. B., Clark, J. S., Norton, A. J., Crowther, P. A., Tauris, T. M., Langer, N., Negueruela, I. and Roche, P. (2012), The evolution and masses of the neutron star and donor star in the high mass X-ray binary OAO 1657−415. Monthly Notices of the Royal Astronomical Society, 422: 199–206. doi: 10.1111/j.1365-2966.2012.20596.x

Author Information

  1. 1

    Department of Physics & Astronomy, The Open University, Milton Keynes, MK7 6AA

  2. 2

    Department of Physics & Astronomy, University of Sheffield, Sheffield, S3 7RH

  3. 3

    Argelander Institut für Astronomie, University of Bonn, Auf dem Hügel 71, D-53121, Bonn, Germany

  4. 4

    Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

  5. 5

    Astronomical Institute, Utrecht University, Princetonplein 5, 3584 CC, Utrecht, the Netherlands

  6. 6

    Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Apdo. 99, E03080 Alicante, Spain

  7. 7

    School of Physics & Astronomy, Cardiff University, The Parade, Cardiff, CF24 3AA

  8. 8

    Division of Earth, Space & Environment, University of Glamorgan, Pontypridd, CF37 1DL

* Based on observations carried out at the European Southern Observatory under programme ID 081.D-0073(B).
E-mail: a.mason@open.ac.uk

Publication History

  1. Issue published online: 17 APR 2012
  2. Article first published online: 5 MAR 2012
  3. Accepted 2012 January 18. Received 2012 January 18; in original form 2011 February 15

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Keywords:

  • binaries: eclipsing;
  • binaries: general;
  • stars: individual: OAO 1657−415;
  • stars: massive;
  • stars: Wolf–Rayet;
  • X-rays: binaries

ABSTRACT

We report near-infrared radial velocity (RV) measurements of the recently identified donor star in the high mass X-ray binary (HMXB) system OAO 1657−415 obtained in the H band using ISAAC on the Very Large Telescope.

Cross-correlation methods were employed to construct a RV curve with a semi-amplitude of 22.1 ± 3.5 km s−1. Combined with other measured parameters of this system it provides a dynamically determined neutron star (NS) mass of 1.42 ± 0.26 M⊙ and a mass of 14.3 ± 0.8 M⊙ for the Ofpe/WN9 highly evolved donor star.

OAO 1657−415 is an eclipsing HMXB pulsar with the largest eccentricity and orbital period of any within its class. Of the 10 known eclipsing X-ray binary pulsars OAO 1657−415 becomes the ninth with a dynamically determined NS mass solution and only the second in an eccentric system. Furthermore, the donor star in OAO 1657−415 is much more highly evolved than the majority of the supergiant donors in other HMXBs, joining a small but growing list of HMXBs donors with extensive hydrogen depleted atmospheres.

Considering the evolutionary development of OAO 1657−415, we have estimated the binding energy of the envelope of the mass donor and find that there is insufficient energy for the removal of the donor’s envelope via spiral-in, ruling out a common envelope evolutionary scenario. With its non-zero eccentricity and relatively large orbital period the identification of a definitive evolutionary pathway for OAO 1657−415 remains problematic, we conclude by proposing two scenarios which may account for OAO 1657−415 current orbital configuration.

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