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Title: IS WX CEN A POSSIBLE TYPE Ia SUPERNOVA PROGENITOR WITH WIND-DRIVEN MASS TRANSFER?

WX Cen is one of a few compact binary supersoft X-ray sources (CBSS) in the Galaxy that is a possible Type Ia supernova (SN Ia) progenitor. The supersoft X-ray radiation is explained as hydrostatic nuclear burning on the surface of the white dwarf component that is accreting hydrogen from a stellar companion at a high rate. If the mass donor in this system has a low mass, as has been suggested in the literature, one would expect a high wind-driven mass transfer rate. In that case, the orbital period of the system should increase. To test this theoretical prediction, we have monitored the system photometrically since 2010. By using four newly determined eclipse timings together with those collected from the literature, we discovered that the orbital period is decreasing at a rate of dP/dt = -5.15 Multiplication-Sign 10{sup -7} days yr{sup -1}. The long-term decrease in the orbital period is contrary to the prediction that the system is powered by wind-driven accretion. It therefore seems plausible that the mass donor could be more massive than the white dwarf, and that the mass transfer is driven by the thermal instability of the donor star. This finding suggests that WX Cen ismore » a key object to check the physical mechanisms of mass accretion in CBSS. The corresponding timescale of the period change is about P/P-dot {approx} 0.81 x 10{sup 6} yr, indicating that WX Cen may evolve into an SNe Ia within one million years in the Galaxy.« less
Authors:
; ; ; ; ;  [1] ; ;  [2]
  1. Yunnan Observatories, Chinese Academy of Sciences (CAS), P.O. Box 110, 650011 Kunming (China)
  2. Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, 1900 La Plata, Buenos Aires (Argentina)
Publication Date:
OSTI Identifier:
22140334
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 772; 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; BINARY STARS; ECLIPSE; FORECASTING; GALAXIES; HYDROGEN; IMAGES; INSTABILITY; MASS TRANSFER; STAR EVOLUTION; STELLAR WINDS; SUPERNOVAE; SURFACES; WHITE DWARF STARS; X RADIATION; X-RAY SOURCES