Optical spectroscopy of the quiescent counterpart to EXO 0748-676
Bassa, C. G., Jonker, P. G., Steeghs, D. (Danny), 1972- and Torres, M. A. P.. (2009) Optical spectroscopy of the quiescent counterpart to EXO 0748-676. Monthly Notices of the Royal Astronomical Society, Vol.399 (No.4). pp. 2055-2062. ISSN 0035-8711Full text not available from this repository.
Official URL: http://dx.doi.org/10.1111/j.1365-2966.2009.15395.x
We present phase resolved optical spectroscopy and X-ray timing of the neutron star X-ray binary EXO 0748-676 after the source returned to quiescence in the autumn of 2008. The X-ray light curve displays eclipses consistent in orbital period, orbital phase and duration with the predictions and measurements before the return to quiescence. Ha and He I emission lines are present in the optical spectra and show the signature of the orbit of the binary companion, placing a lower limit on the radial velocity semi-amplitude of K-2 > 405 km s(-1). Both the flux in the continuum and the emission lines show orbital modulations, indicating that we observe the hemisphere of the binary companion that is being irradiated by the neutron star. Effects due to this irradiation preclude a direct measurement of the radial velocity semi-amplitude of the binary companion; in fact, no stellar absorption lines are seen in the spectrum. Nevertheless, our observations place a stringent lower limit on the neutron star mass of M-1 > 1.27 M-circle dot. For the canonical neutron star mass of M-1 = 1.4 M-circle dot, the mass ratio is constrained to 0.075 < q < 0.105.
|Item Type:||Journal Article|
|Subjects:||Q Science > QB Astronomy|
|Divisions:||Faculty of Science > Physics|
|Journal or Publication Title:||Monthly Notices of the Royal Astronomical Society|
|Date:||11 November 2009|
|Number of Pages:||8|
|Page Range:||pp. 2055-2062|
|Access rights to Published version:||Restricted or Subscription Access|
|Funder:||Netherlands Organisation for Scientific Research (NWO), NASA, STFC Advanced Fellowship|
|Grant number:||G08-9041X, G09-8055X|
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