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Table 4

Updated system parameters: median values and 1-σ limits of the posterior PDFs derived from our global MCMC analysis of all nonblended and partial transits of Trappist-1 planets observed by Spitzer.

Parameters Value
Star TRAPPIST-1
Mass (a) M⋆ (M⊙) 0.0898 ± 0.0023
Radius R⋆ (R⊙) 0.1234 ± 0.0033
Density ρ⋆ (ρ⊙) 47.98 ± 3.90
Luminosity (a) L⋆ (L⊙) 0.000552 ± 0.000018
Effective temperature (K) 2520 ± 39
Metallicity (a) [Fe/H] (dex) 0.0535 ± 0.088
LD coefficient, u1,3.6 μm (a) 0.168 ± 0.016
LD coefficient, u2,3.6 μm (a) 0.245 ± 0.019
LD coefficient, u1,4.5 μm (a) 0.141 ± 0.016
LD coefficient, u2,4.5 μm (a) 0.198 ± 0.018
Combined LD coefficient, c1, 3.6 μm 0.581 ± 0.039
Combined LD coefficient, c2, 3.6 μm − 0.322 ± 0.045
Combined LD coefficient, c1, 4.5 μm 0.482 ± 0.031
Combined LD coefficient, c2, 4.5 μm − 0.256 ± 0.044
Planets b c d e f g h
                 
# of transits 54 39 20 17 13 9 6
Period (days) 1.51088432 ± 0.00000015 2.42179346± 0.00000023 4.04978035± 0.00000266 6.09956479±0.00000178 9.20659399±0.00000212 12.3535557±0.00000341 18.7672745±0.00001876
Mid-transit time T0 - 2450000 (BJDTDB) 7322.514193 ± 0.0000030 7282.8113871± 0.0000038 7670.1463014± 0.0000184 7660.3676621±0.0000143 7671.3737299±0.0000157 7665.3628439±0.0000206 7662.5741486±0.0000913
                 
Transit depth () at 4.5 μm (%) 0.7236 ± 0.0072 0.7027 ± 0.0068 0.3689 ± 0.0067 0.4936 ± 0.0081 0.6313 ± 0.0091 0.745 ± 0.011 0.351 ± 0.012
Transit depth () at 3.6 μm (%) 0.7209 ± 0.0067 0.721 ± 0.014 0.351 ± 0.016 0.491 ± 0.011 0.655 ± 0.019 0.724 ± 0.024 0.313 ± 0.027
Transit impact parameter b (R*) 0.391 ± 0.056 0.430 ± 0.049 0.448 ± 0.054
Transit duration T14 (min) 36.309 ± 0.093 42.42 ± 0.12 49.37 ± 0.32 56.31 ± 0.25 63.28 ± 0.31 69.10 ± 0.36 76.28 ± 0.81
Rp ∕R⋆ at 4.5μm 0.085062 ± 0.000042 0.083827 ± 0.000040 0.06073 ± 0.00056 0.07025 ± 0.00058 0.07945 ± 0.00057 0.08632 ± 0.0062 0.05927 ± 0.0099
Rp ∕R⋆ at 3.6μm 0.084903 ± 0.00040 0.08495 ± 0.00086 0.0593 ± 0.0013 0.07009 ± 0.00075 0.0809 ± 0.0013 0.0851 ± 0.0014 0.0559 ± 0.0025
Inclination i (°) 89.28 ± 0.32 89.47 ± 0.24 89.65 ± 0.15 89.663 ± 0.092 89.666 ± 0.059 89.698 ± 0.044 89.763 ± 0.037
Semi major axis a (10−3 AU)
Scale parameter a∕R⋆
Irradiation Sp (S⊙) 4.15 ± 0.16 2.211 ± 0.085 1.114 ± 0.043 0.645 ± 0.025 0.373 ± 0.014 0.252 ± 0.0097 0.144 ± 0.0055
Equilibrium temperature Teq (K) (b) 397.6 ± 3.8 339.7 ± 3.3 286.2 ± 2.8 249.7 ± 2.4 217.7 ± 2.1 197.3 ± 1.9 171.7 ± 1.7
Radius Rp,3.6μm (R⊕) 1.1407 ± 0.035 1.141 ± 0.037 0.799 ± 0.026 0.944 ± 0.025 1.087 ± 0.027 1.147 ± 0.041 0.752 ± 0.037
Radius Rp,4.5μm (R⊕) 1.144 ± 0.027 1.128 ± 0.027 0.817 ± 0.022 0.945 ± 0.026 1.068 ± 0.028 1.161 ± 0.030 0.797 ± 0.025

Notes. (a) Informative prior PDFs were assumed for these stellar parameters, (b)where Teq is computed from , assuming a null Bond albedo.

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