BEBOP II: Sensitivity to sub-Saturn circumbinary planets using radial-velocities

Matthew R. Standing, Amaury H. M. J. Triaud, João P. Faria, David V. Martin, Isabelle Boisse, Alexandre C. M. Correia, Magali Deleuil, Georgina Dransfield, Michaël Gillon, Guillaume Hébrard, Coel Hellier, Vedad Kunovac, Pierre F. L. Maxted, Rosemary Mardling, Alexandre Santerne, Lalitha Sairam, Stéphane Udry

Research output: Contribution to journalArticlepeer-review

Abstract

BEBOP is a radial-velocity survey that monitors a sample of single-lined eclipsing binaries, in search of circumbinary planets by using high-resolution spectrographs. Here, we describe and test the methods we use to identify planetary signals within the BEBOP data, and establish how we quantify our sensitivity to circumbinary planets by producing detection limits. This process is made easier and more robust by using a diffusive nested sampler. In the process of testing our methods, we notice that contrary to popular wisdom, assuming circular orbits in calculating detection limits for a radial velocity survey provides over-optimistic detection limits by up to $40\%$ in semi-amplitude with implications for all radial-velocity surveys. We perform example analyses using three BEBOP targets from our Southern HARPS survey. We demonstrate for the first time a repeated ability to reach a residual root mean squared scatter of $3~\rm m.s^{-1}$ (after removing the binary signal), and find we are sensitive to circumbinary planets with masses down to that of Neptune and Saturn, for orbital periods up to $1000~\rm days$.
Original languageEnglish
Pages (from-to)3571 - 3583
JournalMonthly Notices of the Royal Astronomical Society
Volume511
Issue number3
Early online date25 Jan 2022
DOIs
Publication statusE-pub ahead of print - 25 Jan 2022

Bibliographical note

17 pages, 11 figures

Keywords

  • techniques: radical velocities
  • planets and satellites: detection
  • binaries: eclipsing
  • stars: low-mass

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