Astron. Astrophys. 332, 561-568 (1998)

Phase-resolved spectroscopy of the low-mass X-ray binaries 1636-536/V 801 Arae and 1735-444/V 926 Scorpii ^*

T. Augusteijn ^{1, 2}, F. van der Hooft ², J.A. de Jong ², M.H. van Kerkwijk ^{2, 4} and J. van Paradijs <sup>2, 3

1</sup> European Southern Observatory, Casilla 19001, Santiago 19, Chile
² Astronomical Institute "Anton Pannekoek", University of Amsterdam and Center for High Energy Astrophysics, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
³ Physics Department University of Huntsville in Alabama, Huntsville, AL 35899, USA
⁴ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK

Received 3 October 1997 / Accepted 12 December 1997

Abstract

We present phase-resolved spectroscopy of the optical counterparts V 801 Ara and V 926 Sco of the low-mass X-ray binaries 1636-536 and 1735-444. To assist in the interpretation of the spectroscopic observations we derive new ephemerides for the photometric variations of both sources. Superior conjunction of the line emission region occurs at photometric phase 0.7 in both sources, which indicates that these variations are dominated by a component originating from the point where the mass stream from the donor star intersects the outer disk. We find that the properties of 1636-536/V 801 Ara and 1735-444/V 926 Sco are very similar.

Key words: accretion, accretion disks X-rays: stars stars: individual: V 801 Ara stars: individual: V 926 Sco stars: neutron

* Based on observations made at the European Southern Observatory, La Silla, Chile

Send offprint requests to: T. Augusteijn

© European Southern Observatory (ESO) 1998

Online publication: March 23, 1998
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