Optical spectroscopy and photometry of SAX J1808.4-3658 in outburst

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dc.contributor.author Elebert, Patrick
dc.contributor.author Reynolds, M. T.
dc.contributor.author Callanan, Paul J.
dc.contributor.author Hurley, Daniel Jason
dc.contributor.author Ramsay, G.
dc.contributor.author Lewis, F.
dc.contributor.author Russell, D. M.
dc.contributor.author Nord, B.
dc.contributor.author Kane, S. R.
dc.contributor.author DePoy, D. L.
dc.contributor.author Hakala, P.
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., Reynolds, M. T., Callanan, P. J., Hurley, D. J., Ramsay, G., Lewis, F., Russell, D. M., Nord, B., Kane, S. R., DePoy, D. L. and Hakala, P. (2009) 'Optical spectroscopy and photometry of SAX J1808.4−3658 in outburst', Monthly Notices of the Royal Astronomical Society, 395(2), pp. 884-894. doi: 10.1111/j.1365-2966.2009.14562.x en
dc.identifier.volume 395
dc.identifier.issued 2
dc.identifier.startpage 884
dc.identifier.endpage 894
dc.identifier.issn 0035-8711
dc.identifier.issn 1365-2966
dc.identifier.uri http://hdl.handle.net/10468/4971
dc.identifier.doi 10.1111/j.1365-2966.2009.14562.x
dc.description.abstract We present phase resolved optical spectroscopy and photometry of V4580 Sagittarii, the optical counterpart to the accretion powered millisecond pulsar SAX J1808.4-3658, obtained during the 2008 September/October outburst. Doppler tomography of the NIII lambda 4640.64 Bowen blend emission line reveals a focused spot of emission at a location consistent with the secondary star. The velocity of this emission occurs at 324 +/- 15 km s(-1); applying a 'K-correction', we find the velocity of the secondary star projected on to the line of sight to be 370 +/- 40 km s-1. Based on existing pulse timing measurements, this constrains the mass ratio of the system to be 0.044(-0.004)(+0.005), and the mass function for the pulsar to be 0.44(-0.13)(+0.16)M(circle dot). Combining this mass function with various inclination estimates from other authors, we find no evidence to suggest that the neutron star in SAX J1808.4-3658 is more massive than the canonical value of 1.4M(circle dot). Our optical light curves exhibit a possible superhump modulation, expected for a system with such a low mass ratio. The equivalent width of the CaII H and K interstellar absorption lines suggest that the distance to the source is similar to 2.5 kpc. This is consistent with previous distance estimates based on type-IX-ray bursts which assume cosmic abundances of hydrogen, but lower than more recent estimates which assume helium-rich bursts. en
dc.description.sponsorship European Southern Observatory (DDT 281, D-5060, 281. D-5061); Fermilab (DE-AC02-07CH11359);Las Cumbres Observatory ( Faulkes Telescope Project ) 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.1365-2966.2009.14562.x
dc.rights © 2009, the Authors. Journal compilation © 2009, RAS en
dc.subject Accretion en
dc.subject Accretion discs en
dc.subject Binaries en
dc.subject Close en
dc.subject Stars en
dc.subject Individual en
dc.subject V4580 Sagittarii en
dc.subject Stars en
dc.subject Neutron en
dc.subject Pulsars en
dc.subject Individual en
dc.subject SAX J1808.4-3658 en
dc.subject X-rays en
dc.subject Binaries en
dc.title Optical spectroscopy and photometry of SAX J1808.4-3658 in outburst 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 Dill Faulkes Educational Trust
dc.contributor.funder Science Foundation Ireland
dc.contributor.funder Fermilab
dc.contributor.funder Las Cumbres Observatory
dc.contributor.funder European Southern Observatory
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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