TOI 4201 b and TOI 5344 b: Discovery of Two Transiting Giant Planets around M-dwarf Stars and Revised Parameters for Three Others

Abstract

We present the discovery from the TESS mission of two giant planets transiting M-dwarf stars: TOI 4201 b and TOI 5344 b. We also provide precise radial velocity measurements and updated system parameters for three other M dwarfs with transiting giant planets: TOI 519, TOI 3629, and TOI 3714. We measure planetary masses of 0.525 ± 0.064 M J, 0.243 ± 0.020 M J, 0.689 ± 0.030 M J, 2.57 ± 0.15 M J, and 0.412±0.040 M J for TOI 519 b, TOI 3629 b, TOI 3714 b, TOI 4201 b, and TOI 5344 b, respectively. The corresponding stellar masses are 0.372 ± 0.018 M ☉, 0.635 ± 0.032 M ☉, 0.522 ± 0.028 M ☉, 0.626 ± 0.033 M ☉, and 0.612 ± 0.034 M ☉. All five hosts have supersolar metallicities, providing further support for recent findings that, like for solar-type stars, close-in giant planets are preferentially found around metal-rich M-dwarf host stars. Finally, we describe a procedure for accounting for systematic errors in stellar evolution models when those models are included directly in fitting a transiting planet system.

TOI-5344 b: A Saturn-like Planet Orbiting a Super-solar Metallicity M0 Dwarf

“…We show the SED fit in Figure 6 and list the derived model-dependent stellar parameters in Table 2. Our adopted stellar parameters derived from EXOFASTv2 agree within 1σ of the results from Hartman et al (2023), including the stellar mass, radius, luminosity, and age. We omit the EXOFASTv2 estimations of the effective temperature, metallicity, and surface gravity since they are statistically equivalent to the adopted HPF-SpecMatch results.…”

“…Further discussion on the absence of rotation signal in long baseline photometry is in Section 3.4. We list the derived effective temperature, metallicity, and surface gravity of TOI-5344 in Table 2, which agree within 1σ of the results from Hartman et al (2023).…”

“…All planetary parameters in Table 3 agree within 1σ with the corresponding values from Hartman et al (2023), except for the planet radius. Hartman et al (2023) reports a planet radius of 0.946 ± 0.021 R Jup , which is larger than our calculation of 0.87 ± 0.04 R Jup by more than 1σ.…”

“…While the uncertainties are large, both metallicity determination methods agree that the [Fe/H] of TOI-5344 is considerably higher than Solar, at a 3-4 σ significance level. Hartman et al (2023) reports a comparable spectroscopic metallicity of [Fe/H]= 0.390 ± 0.090, confirming TOI-5344ʼs super-solar metallicity.…”

“…We discuss TOI 5344 b in the GEMS parameter space in Section 5 and conclude our findings in Section 6. We also quantitatively compare our results to that of Hartman et al (2023) on the same planet in each relevant section. ).…”