skip to main content

Title: VARIABILITY OF THE ACCRETION DISK OF V926 Sco INFERRED FROM TOMOGRAPHIC ANALYSIS

We present phase-resolved spectroscopic observations of the low-mass X-ray binary V926 Sco (4U 1735-44), covering the orbital period of 0.23 days, obtained with the Walter Baade 6.5 m Magellan Telescope at the Las Campanas Observatory in 2010 June and 2011 June. We use Hα radial velocities to derive a systemic velocity of –109 ± 4 km s{sup –1}. The FWHM of the lines observed in common with previous authors are significantly lower during our observations suggesting much reduced velocities in the system. The equivalent width of the Bowen fluorescence lines with respect to He II λ4686 are factors of two or more lower during our observations in comparison to those previously reported for the system, suggesting reduced irradiation of the secondary. Doppler and modulation tomography of Hα and He II λ4686 show asymmetric emission that can be attributed to a bulge in the accretion disk, as inferred from He II observations by previous authors. The X-ray fluxes from the source at times concurrent with the optical observations are significantly lower during our observations than during optical observations taken in 2003. We suggest that the system is in a lower accretion state compared to earlier observations; this explains both the lowermore » velocities observed from the disk and the reduction of emission due to Bowen fluorescence detected from the secondary.« less
Authors:
 [1] ;  [2] ;  [3]
  1. University of Southampton, Highfield, Southampton, S017 1BJ (United Kingdom)
  2. Department of Physics, Northeastern University, Boston, MA 02115 (United States)
  3. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22270557
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 777; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; ASTRONOMY; ASTROPHYSICS; ASYMMETRY; BINARY STARS; COMPARATIVE EVALUATIONS; COSMIC X-RAY SOURCES; FLUORESCENCE; HELIUM IONS; IRRADIATION; MODULATION; RADIAL VELOCITY; TELESCOPES; X RADIATION