The EBLM project – VIII. First results for M-dwarf mass, radius, and effective temperature measurements using CHEOPS light curves

The accuracy of theoretical mass, radius, and effective temperature values for M-dwarf stars is an active topic of debate. Differences between observed and theoretical values have raised the possibility that current theoretical stellar structure and evolution models are inaccurate towards the low-mass end of the main sequence. To explore this issue, we use the CHEOPS satellite to obtain high-precision light curves of eclipsing binaries with low-mass stellar companions. We use these light curves combined with the spectroscopic orbit for the solar-type companion to measure the mass, radius, and effective temperature of the M-dwarf star. Here, we present the analysis of three eclipsing binaries. We use the pycheops data analysis software to fit the observed transit and eclipse events of each system. Two of our systems were also observed by the TESS satellite – we similarly analyse these light curves for comparison. We find consistent results between CHEOPS and TESS, presenting three stellar radii and two stellar effective temperature values of low-mass stellar objects. These initial results from our on-going observing programme with CHEOPS show that we can expect to have ∼24 new mass, radius, and effective temperature measurements for very low-mass stars within the next few years.

Citation

Swayne , M I , Maxted , P F L , Triaud , A H M J , Sousa , S G , Broeg , C , Florén , H-G , Guterman , P , Simon , A E , Boisse , I , Bonfanti , A , Martin , D , Santerne , A , Salmon , S , Standing , M R , Van Grootel , V , Wilson , T G , Alibert , Y , Alonso , R , Anglada Escudé , G , Asquier , J , Bárczy , T , Barrado , D , Barros , S C C , Battley , M , Baumjohann , W , Beck , M , Beck , T , Bekkelien , A , Benz , W , Billot , N , Bonfils , X , Brandeker , A , Busch , M-D , Cabrera , J , Charnoz , S , Collier Cameron , A , Csizmadia , S , Davies , M B , Deleuil , M , Deline , A , Delrez , L , Demangeon , O D S , Demory , B-O , Dransfield , G , Ehrenreich , D , Erikson , A , Fortier , A , Fossati , L , Fridlund , M , Futyan , D , Gandolfi , D , Gillon , M , Guedel , M , Hébrard , G , Heidari , N , Hellier , C , Heng , K , Hobson , M , Hoyer , S , Isaak , K G , Kiss , L , Kunovac Hodžić , V , Lalitha , S , Laskar , J , Lecavelier des Etangs , A , Lendl , M , Lovis , C , Magrin , D , Marafatto , L , McCormac , J , Miller , N , Nascimbeni , V , Olofsson , G , Ottensamer , R , Pagano , I , Pallé , E , Peter , G , Piotto , G , Pollacco , D , Queloz , D , Ragazzoni , R , Rando , N , Rauer , H , Ribas , I , Santos , N C , Scandariato , G , Ségransan , D , Smith , A M S , Steinberger , M , Steller , M , Szabó , G M , Thomas , N , Udry , S , Walter , I , Walton , N A & Willett , E 2021 , ' The EBLM project – VIII. First results for M-dwarf mass, radius, and effective temperature measurements using CHEOPS light curves ' , Monthly Notices of the Royal Astronomical Society , vol. 506 , no. 1 , pp. 306-322 . https://doi.org/10.1093/mnras/stab1687

Publication

Monthly Notices of the Royal Astronomical Society

Status

Peer reviewed

DOI

https://doi.org/10.1093/mnras/stab1687

ISSN

0035-8711

Type

Journal article

Rights

Copyright 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the final published version of the work, which was originally published at https://doi.org/10.1093/mnras/stab1687.

Description

Funding: MIS and PFLM are supported by the UK Science and Technology Facilities Council (STFC) grant numbers ST/M001040/1 and ST/T506175/1. This research is supported from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 803193/BEBOP), by a Leverhulme Trust Research Project Grant No. (RPG-2018-418)ACC and TW acknowledge support from STFC consolidated grant no. ST/M001296/1.

Collections

University of St Andrews Research

URI

http://hdl.handle.net/10023/24065