The EBLM project X. benchmark masses, radii and temperatures for two fully convective M-dwarfs using K2

Duck, Alison; Martin, David V; Gill, Sam; Armitage, Tayt; Rodríguez Martínez, Romy; Maxted, Pierre F L; Sebastian, Daniel; Sethi, Ritika; Swayne, Matthew I; Cameron, Andrew Collier; Dransfield, Georgina; Gaudi, B Scott; Gillon, Michael; Hellier, Coel; Kunovac, Vedad; Lovis, Christophe; McCormac, James; Pepe, Francesco A; Pollacco, Don; Sairam, Lalitha; Santerne, Alexandre; Ségransan, Damien; Standing, Matthew R; Southworth, John; Triaud, Amaury H M J; Udry, Stephane

Abstract

M-dwarfs are the most abundant stars in the galaxy and popular targets for exoplanet searches. However, their intrinsic faintness and complex spectra inhibit precise characterisation. We only know of dozens of M-dwarfs with fundamental parameters of mass, radius and effective temperature characterised to better than a few per cent. Eclipsing binaries remain the most robust means of stellar characterisation. Here we present two targets from the Eclipsing Binary Low Mass (EBLM) survey that were observed with K2: EBLM J0055-00 and EBLM J2217-04. Combined with HARPS and CORALIE spectroscopy, we measure M-dwarf masses with precisions better than 5%, radii better than 3% and effective temperatures on order 1%. However, our fits require invoking a model to derive parameters for the primary star and fitting the M-dwarf using the transit and radial velocity observations. By investigating three popular stellar models, we determine that the model uncertainty in the primary star is of similar magnitude to the statistical uncertainty in the model fits of the secondary M-dwarf. Therefore, whilst these can be considered benchmark M-dwarfs, we caution the community to consider model uncertainty when pushing the limits of precise stellar characterisation.

Citation

Duck, A., Martin, D. V., Gill, S., Armitage, T., Rodríguez Martínez, R., Maxted, P. F. L., …Udry, S. (2023). The EBLM project X. benchmark masses, radii and temperatures for two fully convective M-dwarfs using K2. Monthly Notices of the Royal Astronomical Society, 521(4), 6305-6317. https://doi.org/10.1093/mnras/stad452

• Journal Article Type: Article
• Acceptance Date: Jan 27, 2023
• Online Publication Date: Feb 24, 2023
• Publication Date: 2023-06
• Publicly Available Date: May 30, 2023
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 521
• Issue: 4
• Pages: 6305-6317
• DOI: https://doi.org/10.1093/mnras/stad452
• Keywords: techniques; photometric - techniques; spectroscopic - binaries eclipsing - stars; fundamental parameters - stars; low-mass
• Publisher URL: https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stad452/7057889?redirectedFrom=fulltext