Optical spectroscopy and Doppler tomography of Cygnus X-2

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dc.contributor.author Elebert, Patrick
dc.contributor.author Callanan, Paul J.
dc.contributor.author Torres, M. A. P.
dc.contributor.author Garcia, M. R.
dc.date.accessioned 2017-11-07T09:38:56Z
dc.date.available 2017-11-07T09:38:56Z
dc.date.issued 2009
dc.identifier.citation Elebert, P., Callanan, P. J., Torres, M. A. P. and Garcia, M. R. (2009) 'Optical spectroscopy and Doppler tomography of Cygnus X-2', Monthly Notices of the Royal Astronomical Society, 395(4), pp. 2029-2038. doi: 10.1111/j.1365-2966.2009.14685.x en
dc.identifier.volume 395
dc.identifier.issued 4
dc.identifier.startpage 2029
dc.identifier.endpage 2038
dc.identifier.issn 0035-8711
dc.identifier.uri http://hdl.handle.net/10468/4970
dc.identifier.doi 10.1111/j.1365-2966.2009.14685.x
dc.description.abstract We present phase resolved optical spectroscopy and Doppler tomography of V1341 Cygni, the optical counterpart to the neutron star low-mass X-ray binary (LMXB) Cygnus X-2 (Cyg X-2). We derive a radial velocity (RV) curve for the secondary star, finding a projected RV semi-amplitude of K(2) = 79 +/- 3 km s(-1), leading to a mass function of 0.51 +/- 0.06 M(circle dot), similar to 30 per cent lower than the previous estimate. We tentatively attribute the lower value of K(2) (compared to that obtained by other authors) to variations in the X-ray irradiation of the secondary star at different epochs of observations. The limited phase coverage and/or longer timebase of previous observations may also contribute to the difference in K(2). Our value for the mass function implies a primary mass of 1.5 +/- 0.3 M(circle dot), somewhat lower than previous dynamical estimates, but consistent with the value found by analysis of type-I X-ray bursts from this system. Our Doppler tomography of the broad He II lambda 4686 line reveals that most of the emission from this line is produced on the irradiated face of the donor star, with little emission from the accretion disc. In contrast, the Doppler tomogram of the N III lambda 4640.64 Bowen blend line shows bright emission from near the gas stream/accretion disc impact region, with fainter emission from the gas stream and secondary star. This is the first LMXB for which the Bowen blend is dominated by emission from the gas stream/accretion disc impact region, without comparable emission from the secondary star. This has implications for the interpretation of Bowen blend Doppler tomograms of other LMXBs for which the ephemeris may not be accurately known. en
dc.description.sponsorship NASA (NAS8-03060) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Oxford University Press en
dc.relation.uri https://academic.oup.com/mnras/article-lookup/doi/10.1111/j.1365-2966.2009.14685.x
dc.rights © 2009, the Authors. Journal compilation © 2009, RAS en
dc.subject Accretion en
dc.subject Accretion discs en
dc.subject Stars en
dc.subject Individual en
dc.subject Cygnus X-2 en
dc.subject V1341 Cygni en
dc.subject Stars en
dc.subject Neutron en
dc.subject X-rays en
dc.subject Binaries en
dc.title Optical spectroscopy and Doppler tomography of Cygnus X-2 en
dc.type Article (peer-reviewed) en
dc.internal.authorcontactother Patrick Elebert, Physics, University College Cork, Cork, Ireland. +353-21-490-3000 Email: p.elebert@ucc.ie en
dc.internal.availability Full text available en
dc.description.version Published Version en
dc.contributor.funder Science Foundation Ireland
dc.contributor.funder National Aeronautics and Space Administration
dc.description.status Peer reviewed en
dc.identifier.journaltitle Monthly Notices of the Royal Astronomical Society en
dc.internal.IRISemailaddress p.elebert@ucc.ie en

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