The TESS light curve of the eccentric eclipsing binary 1SWASP J011351.29+314909.7 -- no evidence for a very hot M-dwarf companion

Abstract

A 2014 study of the eclipsing binary star 1SWASPJ011351.29+314909.7 (J0113+31) reported an unexpectedly high effective temperature for the M-dwarf companion to the 0.95-M${}_{\odot }$ primary star. The effective temperature inferred from the secondary eclipse depth was $\sim$600 K higher than the value predicted from stellar models. Such an anomalous result questions our understanding of low-mass stars and might indicate a significant uncertainty when inferring properties of exoplanets orbiting them. We seek to measure the effective temperature of the M-dwarf companion using the light curve of J0113+31 recently observed by the Transiting Exoplanet Survey Satellite (TESS). We use the pycheops modelling software to fit a combined transit and eclipse model to the TESS light curve. To calculate the secondary effective temperature, we compare the best-fit eclipse depth to the predicted eclipse depths from theoretical stellar models. We determined the effective temperature of the M dwarf to be ${\mathrm{T}}_{\mathrm{eff},2}$ = 3208 $\pm$ 43 K, assuming $\log g_2$ = 5, [Fe/H] = $-0.4$ and no alpha-element enhancement. Varying these assumptions changes ${\mathrm{T}}_{\mathrm{eff},2}$ by less than 100 K. These results do not support a large anomaly between observed and theoretical low-mass star temperatures.

5 pages, 3 figures, published in MNRAS

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Cited by in corpus (5)

• The EBLM project -- VIII. First results for M-dwarf mass, radius and effective temperature measurements using CHEOPS light curves
• Fundamental Properties of Late-Type Stars in Eclipsing Binaries
• The EBLM project X. Benchmark masses, radii and temperatures for two fully convective M-dwarfs using K2
• Fundamental effective temperature measurements for eclipsing binary stars -- III. SPIRou near-infrared spectroscopy and CHEOPS photometry of the benchmark G0V star EBLM J0113+31
• The EBLM Project XVIII. 3D Obliquities of Five Low-Mass Eclipsing Binaries