The Open UniversitySkip to content

Preliminary determinations of the masses of the neutron star and mass donor in the high mass X-ray binary system EXO 1722-363

Mason, A. B.; Norton, A. J.; Clark, J. S.; Negueruela, I. and Roche, P. (2010). Preliminary determinations of the masses of the neutron star and mass donor in the high mass X-ray binary system EXO 1722-363. Astronomy & Astrophysics, 509, article no. A79.

Full text available as:
PDF (Accepted Manuscript) - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
Download (673kB)
DOI (Digital Object Identifier) Link:
Google Scholar: Look up in Google Scholar


Aims. We intended to measure the radial velocity curve of the supergiant companion to the eclipsing high mass X-ray binary pulsar EXO 1722–363 and hence determine the stellar masses of the components.

Methods. We used a set of archival Ks-band infrared spectra of the counterpart to EXO 1722–363 obtained using ISAAC on the VLT, and cross-correlated them in order to measure the radial velocity of the star.

Results. The resulting radial velocity curve has a semi-amplitude of 24.5 ± 5.0 km s-1. When combined with other measured parameters of the system, this yields masses in the range 1.5 ± 0.4-1.6 ± 0.4 M for the neutron star and 13.6 ± 1.6-15.2 ± 1.9 M for the B0–1 Ia supergiant companion. These lower and upper limits were obtained under the assumption that the system is viewed edge-on (i = 90°) for the lower limit and the supergiant fills its Roche lobe (β = 1) for the upper limit respectively. The system inclination is constrained to i > 75° and the Roche lobe-filling factor of the supergiant is β > 0.9. Additionally we were able to further constrain our distance determination to be 7.1 ≤ d ≤ 7.9 kpc for EXO 1722–363. The X-ray luminosity for this distance range is 4.7 x 1035 ≤ 9.2 x 1036 erg s-1.

Conclusions. EXO 1722–363 therefore becomes the seventh of the ten known eclipsing X-ray binary pulsars for which a dynamical neutron star mass solution has been determined. Additionally EXO 1722–363 is the first such system to have a neutron star mass measurement made utilising near-infrared spectroscopy.

Item Type: Journal Item
Copyright Holders: 2010 ESO
ISSN: 1432-0746
Extra Information: 4 pp.
Keywords: pulsars; x-ray binaries; eclipsing binaries; EXO 1722-363
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 19032
Depositing User: Andrew Mason
Date Deposited: 01 Dec 2009 14:21
Last Modified: 02 Jul 2020 08:57
Share this page:


Altmetrics from Altmetric

Citations from Dimensions

Download history for this item

These details should be considered as only a guide to the number of downloads performed manually. Algorithmic methods have been applied in an attempt to remove automated downloads from the displayed statistics but no guarantee can be made as to the accuracy of the figures.

Actions (login may be required)

Policies | Disclaimer

© The Open University   contact the OU