Mason, A. B.; Clark, J. S.; Norton, A. J.; Crowther, P. A.; Tauris, T. M.; Langer, N.; Negueruela, I. and Roche, P.
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|DOI (Digital Object Identifier) Link:||http://doi.org/10.1111/j.1365-2966.2012.20596.x|
|Google Scholar:||Look up in Google Scholar|
We report near-infrared radial velocity measurements of the recently identified donor star in the high mass X-ray binary system OAO 1657-415 obtained in the H band using ISAAC on the VLT.
Cross-correlation methods were employed to construct a radial velocity curve with a semi-amplitude of 22.1 ± 3.5 km s-1. Combined with other measured parameters of this system this provides a dynamically determined neutron star 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 High Mass X-ray binary pulsar with the largest eccentricity and orbital period of any within its class. Of the ten known eclipsing X-ray binary pulsars OAO 1657-415 becomes the ninth with a dynamically determined neutron star 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 High Mass X-ray binaries (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 OAO1657-415 remains problematic, we conclude by proposing two scenarios which may account for OAO1657-415 current orbital configuration.
|Item Type:||Journal Article|
|Copyright Holders:||2012 The Authors|
|Keywords:||eclipsing binaries; binaries; OAO 1657−415; Wolf–Rayet; X-ray binaries|
|Academic Unit/Department:||Science > Physical Sciences
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)|
|Depositing User:||Andrew Norton|
|Date Deposited:||03 Feb 2012 09:29|
|Last Modified:||23 Feb 2016 21:16|
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