A low-mass-ratio and deep contact binary as the progenitor of the merger V1309 Sco

Abstract

Nova Sco 2008 (=V1309 Sco) is an example of a V838 Mon type eruption rather than a typical classical nova. This enigmatic object was recently shown to have resulted from the merger of two stars in a contact binary. It is the first stellar merger that was identified to be undergoing a common envelope transient. To understand the properties of its binary progenitor, the pre-outburst light curves were analyzed by using the W-D method. The photometric solution of the 2002 light curve shows that it is a deep contact binary (f = 89.5(+-40.5)%) with a mass ratio of 0.094. The asymmetry of the light curve is explained by the presence of a dark spot on the more massive component. The extremely high fill-out factor suggests that the merging of the contact binary is driven by dynamical mass loss from the outer Lagrange point. However, the analysis of the 2004 light curve indicates that no solutions were obtained even at an extremely low mass ratio of q = 0.03. This suggests that the common convective envelope of the binary system disappeared and the secondary component spiraled into the envelope of the primary in 2004. Finally, the ejection of the envelope of the primary produced the outburst.

arXiv comment7 pages, 4 figures

References in corpus (8)

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• V1309 Scorpii: merger of a contact binary
• Identification of the Long-Sought Common-Envelope Events
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• V1309 SCO - Understanding a merger
• Burying a Binary: Dynamical Mass Loss and a Continuous Optically-Thick Outflow Explain the Candidate Stellar Merger V1309 Scorpii
• Evolution of the progenitor binary of V1309 Scorpii before merger
• High Fill-Out, Extreme Mass Ratio Overcontact Binary Systems. X. The new discovered binary XY Leonis Minoris

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• TY Pup: a low-mass-ratio and deep contact binary as a progenitor candidate of luminous red novae
• Runaway Coalescence of Pre-Common-Envelope Stellar Binaries
• Error Analysis of the Light Curve Solution of Contact Binaries Based on the W-D Code
• The first photometric and spectroscopic analysis of the extremely low mass ratio contact binary NSVS 5029961
• A New Stellar Outburst Associated with the Magnetic Activities of the K-type Dwarf in a White-dwarf Binary
• Multi-color photometric investigation of the totally eclipsing binary NO Cam
• A rapidly fading star as a type II obscuring intermediate luminosity optical transient (ILOT) in a triple star system
• Photometric and spectroscopic studies of the long period low mass ratio deep contact binary KN Per