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An eclipsing M-dwarf close to the hydrogen burning limit from NGTS

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journal contribution
posted on 18.09.2020, 13:28 by Jack S Acton, Michael R Goad, Sarah L Casewell, José I Vines, Matthew R Burleigh, Phillip Eigmüller, Louise D Nielsen, Boris T Gänsicke, Daniel Bayliss, François Bouchy, Edward M Bryant, Samuel Gill, Edward Gillen, Maximilian N Günther, James S Jenkins, James McCormac, Maximiliano Moyano, Liam R Raynard, Rosanna H Tilbrook, Stéphane Udry, Christopher A Watson, Richard G West, Peter J Wheatley
We present the discovery of NGTS J0930-18, an extreme mass ratio eclipsing M-dwarf binary system with an early M-dwarf primary and a late M-dwarf secondary close to the hydrogen burning limit. Global modelling of photometry and radial velocities reveals that the secondary component (NGTS J0930-18 B) has a mass of M=$0.0818 ^{+0.0040}_{-0.0015}$ $M_*$ and radius of R=$0.1059 ^{+0.0023}_{-0.0021}$ $R_*$, making it one of the lowest mass stars with direct mass and radius measurements. With a mass ratio of q =$0.1407 ^{+0.0065}_{-0.017}$, NGTS J0930-18 has the lowest mass ratio of any known eclipsing M-dwarf binary system, posing interesting questions for binary star formation and evolution models. The mass and radius of NGTS J0930-18 B is broadly consistent with stellar evolutionary models. NGTS J0930-18 B lies in the sparsely populated mass radius parameter space close to the substellar boundary. Precise measurements of masses and radii from single lined eclipsing binary systems of this type are vital for constraining the uncertainty in the mass-radius relationship - of importance due to the growing number of terrestrial planets being discovered around low mass stars.

History

Citation

Monthly Notices of the Royal Astronomical Society, staa2513, https://doi.org/10.1093/mnras/staa2513

Author affiliation

Department of Physics and Astronomy

Version

AM (Accepted Manuscript)

Published in

Monthly Notices of the Royal Astronomical Society

Publisher

Oxford University Press (OUP) for Royal Astronomical Society

issn

0035-8711

eissn

1365-2966

Available date

20/08/2020

Language

en

Publisher version

https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/staa2513/5894934?redirectedFrom=fulltext

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