WX Cen (= WR 48c) - a possible type Ia Supernova progenitor

Abstract

We confirm the orbital period of WX Cen (WR 48c) determined by Diaz & Steiner (1995) and refined its value to P = 0.416 961 5 d. The light curve of this object has an amplitude of 0.32 magnitudes and has a V-shaped narrow minimum, similar to the ones seen in V Sge, V617 Sgr and in Compact Binary Supersoft Sources - CBSS. The He II Pickering series decrement shows that the system has significant amount of hydrogen. The He II 4686 emission lines became weaker between the 1991 and 2000/2002 observations, indicating distinct levels of activity. The Balmer lines show variable features with V = -2900 km/s in absorption and with V = +/- 3500 km/s in emission. These highly variable events remind the satellites in emission of CBSS. We estimate the color excess as E(B-V)=0.63. Given the distance-color excess relation in the direction of WX Cen, this implies a distance of 2.8 kpc. Interstellar absorption of the Na I D lines show components at -4.1 km/s, which corresponds to the velocity of the Coalsack, and three other components a -23.9, -32.0 and -39.0 km/s. These components are also seen with similar strengths in field stars that have distances between 1.8 and 2.7 kpc. The intrinsic color of WX Cen is (B-V)0=-0.2 and the absolute magnitude, Mv = -0.5. Extended red wings in the strong emission lines are seen. A possible explanation is that the system has a spill-over stream similar to what is seen in V617 Sgr. We predict that when observed in opposite orbital phase, blue wings would be observed. The velocity of the satellite-like feature is consistent with the idea that the central star is a white dwarf with a mass of M ~ 0.9 Msun. With the high accretion rate under consideration, the star may become a SN Ia in a time-scale of 5 X 10^6 years.

12 pages, 11 EPS figures, preprint of an article accepted for publication in Monthly Notices of The Royal Astronomical Society

References in corpus (1)

• A limit cycle model for long-term optical variations of V Sagittae: The second example of accretion wind evolution

Cited by in corpus (11)

• The Evolution of Compact Binary Star Systems
• Progenitors of Type Ia Supernovae: Binary Stars with White Dwarf Companions
• The qWR star HD 45166. II. Fundamental stellar parameters and evidence of a latitude-dependent wind
• Exploratory Spectroscopy of Magnetic Cataclysmic Variables Candidates and Other Variable Objects
• CAL 87 - an evolved wind-driven supersoft X-ray binary
• QU Carinae: a SNeIa progenitor?
• The orbital period of the V Sge star candidate QU Carinae
• Smoothed Temporal Variance Spectrum: weak line profile variations and NRP diagnostics
• The confirmation and revision on the orbital period change of the possible type Ia supernova progenitor V617 Sagittarii
• Transient jets in V617 Sagittarii
• Penguin and rare decays in BaBar