We have computed, based on 17 infrared radial velocities, the first set of
orbital elements for the M giant in the symbiotic binary V2116 Ophiuchi. The
giant's companion is a neutron star, the bright X-ray source GX 1+4. We find an
orbital period of 1161 days by far the longest of any known X-ray binary. The
orbit has a modest eccentricity of 0.10 with an orbital circularization time of
less than 10^6 years. The large mass function of the orbit significantly
restricts the mass of the M giant. Adopting a neutron-star mass of 1.35M(Sun),
the maximum mass of the M giant is 1.22M(Sun), making it the less massive star.
Derived abundances indicate a slightly subsolar metallicity. Carbon and
nitrogen are in the expected ratio resulting from the red-giant first dredge-up
phase. The lack of O-17 suggests that the M-giant has a mass less than
1.3M(Sun), consistent with our maximum mass. The red giant radius is 103R(Sun),
much smaller than the estimated Roche lobe radius. Thus, the mass loss of the
red giant is via a stellar wind. Although the M giant companion to the neutron
star has a mass similar to the late-type star in low-mass X-ray binaries, its
near-solar abundances and apparent runaway velocity are not fully consistent
with the properties of this class of stars.Comment: In press to The Astrophysical Journal (10 April 2006 issue). 23 page

Bandyopadhyay R.

Batten A. H.

Charbonnel C.

Doty J.

Francis C. Fekel

Glass I. S.

Gustafsson B.

Hut P.

Kenneth H. Hinkle

Kholopov P. N.

Maeder A.

Murset U.

Paul B.

Peter R. Wood

Phinney E. S.

Predehl P.

Richard R. Joyce

Ricketts M. J.

Scarfe C. D.

Schmutz W.

Shahbaz T.

Smith V. V.

Soker N.

Thomas Lebzelter

van den Heuvel E. P. J.

Verne V. Smith

Zahn J.-P.

English

arXiv

We have computed, using 17 infrared radial velocities, the first set of orbital elements for the M giant in the symbiotic binary V2116 Ophiuchi. The giant's companion is a neutron star, the bright X-ray source GX 1+4. We rule out the previously proposed period of 304 days and instead find an orbital period of 1161 days, by far the longest of any known X-ray binary. The orbit has a modest eccentricity of 0.10, with an orbital circularization time of ?5 × 106 yr. The large mass function of the orbit significantly restricts the mass of the M giant. Adopting a neutron star mass of 1.35 M?, the maximum mass of the M giant is 1.22 M?, making it the less massive star. Spectrum synthesis analysis of several infrared spectral regions results in slightly subsolar abundances for most metals. Carbon and nitrogen are in the expected ratio resulting from the red-giant first dredge-up phase. The lack of 17O suggests that the M giant has a mass less than 1.3 M ?, consistent with our maximum mass. The surface gravity and maximum mass of the M giant result in a radius of 103 R?, much smaller than its estimated Roche lobe radius. Thus, the mass loss of the red giant is via a stellar wind. These properties argue that the M giant is near the tip of the first-ascent giant branch. Although the M-giant companion to the neutron star has a mass similar to the late-type star in low-mass X-ray binaries, its near-solar abundances and apparent runaway velocity are not fully consistent with the properties of this class of stars. Thus, in many ways this symbiotic X-ray binary system is unique, and various scenarios for its possible evolution are discussed.  2006. The American Astronomical Society. All rights reserved

Hinkle, Kenneth H. (National Optical Astronomy Observatory)

Fekel, Francis C. (Tennessee State University)

Joyce, Richard R. (National Optical Astronomy Observatory)

Wood, Peter R. (Australian National University)

Smith, Verne V. (National Optical Astronomy Observatory)

Lebzelter, Thomas (Department of Astrophysics, Faculty of Earth Sciences, Geography and Astronomy, University of Vienna)

Permanent Hosting, Archiving and Indexing of Digital Resources and Assets

Infrared spectroscopy of symbiotic stars. IV. V2116 ophiuchi/gx 1+4, the-neutron star symbiotic

We have computed, using 17 infrared radial velocities, the first set of orbital elements for the M giant in the symbiotic binary V2116 Ophiuchi. The giant's companion is a neutron star, the bright X-ray source GX 1+4. We rule out the previously proposed period of 304 days and instead find an orbital period of 1161 days, by far the longest of any known X-ray binary. The orbit has a modest eccentricity of 0.10, with an orbital circularization time of ≲5 × 106 yr. The large mass function of the orbit significantly restricts the mass of the M giant. Adopting a neutron star mass of 1.35 M⊙, the maximum mass of the M giant is 1.22 M⊙, making it the less massive star. Spectrum synthesis analysis of several infrared spectral regions results in slightly subsolar abundances for most metals. Carbon and nitrogen are in the expected ratio resulting from the red-giant first dredge-up phase. The lack of17O suggests that the M giant has a mass less than 1.3 Ṁ, consistent with our maximum mass. The surface gravity and maximum mass of the M giant result in a radius of 103 R⊙, much smaller than its estimated Roche lobe radius. Thus, the mass loss of the red giant is via a stellar wind. These properties argue that the M giant is near the tip of the first-ascent giant branch. Although the M-giant companion to the neutron star has a mass similar to the late-type star in low-mass X-ray binaries, its near-solar abundances and apparent runaway velocity are not fully consistent with the properties of this class of stars. Thus, in many ways this symbiotic X-ray binary system is unique, and various scenarios for its possible evolution are discussed

Hinkle, Kenneth H

Fekel, Francis C

Joyce, Richard R

Wood, Peter R

Smith, Verne V

Lebzelter, Thomas

The Australian National University

The Astrophysical Journal

Infrared Spectroscopy of Symbiotic Stars. IV. V2116 Ophiuchi/gx 1+4, The Neutron Star Symbiotic

We have computed, using 17 infrared radial velocities, the first set of orbital elements for the M giant in the symbiotic binary V2116 Ophiuchi. The giant\u27s companion is a neutron star, the bright X-ray source GX 1+4. We rule out the previously proposed period of 304 days and instead find an orbital period of 1161 days, by far the longest of any known X-ray binary. The orbit has a modest eccentricity of 0.10, with an orbital circularization time of ≲5 × 106 yr. The large mass function of the orbit significantly restricts the mass of the M giant. Adopting a neutron star mass of 1.35 M☉, the maximum mass of the M giant is 1.22 M☉, making it the less massive star. Spectrum synthesis analysis of several infrared spectral regions results in slightly subsolar abundances for most metals. Carbon and nitrogen are in the expected ratio resulting from the red-giant first dredge-up phase. The lack of 17O suggests that the M giant has a mass less than 1.3 M☉, consistent with our maximum mass. The surface gravity and maximum mass of the M giant result in a radius of 103 R☉, much smaller than its estimated Roche lobe radius. Thus, the mass loss of the red giant is via a stellar wind. These properties argue that the M giant is near the tip of the first-ascent giant branch. Although the M-giant companion to the neutron star has a mass similar to the late-type star in low-mass X-ray binaries, its near-solar abundances and apparent runaway velocity are not fully consistent with the properties of this class of stars. Thus, in many ways this symbiotic X-ray binary system is unique, and various scenarios for its possible evolution are discussed

Hinkle, Kenneth H.

Fekel, Francis C.

Joyce, Richard R.

Wood, Peter R.

Smith, Verne V.

Digital Scholarship @ Tennessee State University

Infrared Spectroscopy of Symbiotic Stars. IV. V2116 Ophiuchi/GX 1+4, The Neutron Star Symbiotic

Crossref

http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.338.2929

Infrared Spectroscopy of Symbiotic Stars. IV. V2116 Ophiuchi/GX 1+4, The
  Neutron Star Symbiotic

Infrared Spectroscopy of Symbiotic Stars. IV. V2116 Ophiuchi/GX 1+4, The Neutron Star Symbiotic

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Permanent Hosting, Archiving and Indexing of Digital Resources and Assets

The Australian National University

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