Further evidence of a brown dwarf orbiting the post-common envelope eclipsing binary V470 cam (HS 0705+6700)

Journal article

Several post-common envelope binaries have slightly increasing, decreasing or oscillating orbital periods. One of several possible explanations is light travel-time changes, caused by the binary centre-of-mass being perturbed by the gravitational pull of a third body. Further studies are necessary because it is not clear how a third body could have survived subdwarf progenitor mass-loss at the tip of the Red Giant Branch, or formed subsequently. Thirty-nine primary eclipse times for V470 Cam were secured with the Philip Wetton Telescope during the period 2016 November 25thto 2017 January 27th. Available eclipse timings suggest a brown dwarf tertiary having a mass of at least 0.0236(40) M, an elliptical orbit with an eccentricity of 0.376(98) and an orbital period of 11.77(67) years about the binary centre-of-mass. The mass and orbit suggest a hybrid formation, in which some ejected material from the subdwarf progenitor was accreted on to a precursor tertiary component, although additional observations would be needed to confirm this interpretation and investigate other possible origins for the binary orbital period change.

Authors: Bogensberger, D; Clarke, F; Lynas-Gray, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: De Gruyter
• Journal: Open Astronomy
• Volume: 26
• Issue: 1
• Pages: 134-138
• Publication date: 2017-12-22
• Acceptance date: 2017-10-13
• DOI: 10.1515/astro-2017-0015
• EISSN: 2543-6376
• Keywords: stars: subdwarfs; stars: binaries eclipsing; Journal Article; stars: binaries close