Rapid orbital decay in detached binaries: Evidence for circumbinary disks

Journal article

Some short-period, detached binary systems have recently been reported to experience very rapid orbital decay, much faster than is expected from the angular-momentum loss caused by gravitational radiation alone. As these systems contain fully convective stars, magnetic braking is not believed to be operative, making the large orbital-period derivative puzzling. Here we explore whether a resonant interaction between the binary and a surrounding circumbinary (CB) disk could account for the observed orbital decay. Our calculations indicate that the observed orbital-period derivatives in seven detached binaries can be produced by the resonant interaction between the binary and a CB disk if the latter has a mass in the range of $10^{-4}-10^{-2}~ M_{\odot}$, which is of the same order as the inferred disk mass ($\sim2.4\times 10^{-4}~ M_{\odot}$) in the post-common-envelope binary NN Ser.

Authors: Chen, W; Podsiadlowski, P

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Institute of Physics
• Journal: Astrophysical Journal Letters
• Volume: 837
• Issue: 2
• Pages: L19
• Publication date: 2017-03-01
• Acceptance date: 2017-02-21
• DOI: 10.3847/2041-8213/aa624a
• EISSN: 2041-8213
• ISSN: 2041-8205
• Keywords: stars: low-mass; binaries: close; white dwarfs; stars: individual (NN Ser); stars: evolution