K6.5V Henry02 does not list a K6.5V standard. Gray06 classified 11 stars as K6.5V - none have published Teffs in PASTEL compendium. Teff(K7V) = 4070K ; K7V adopted Teff(K6.5V) = 4090K ; non-standard GJ 826.1/HD 203040 Teff(K6.5V) = 4175K ; non-standard GJ 9646/HD 178445 Teff(K6.5V) = 4190K ; smooth Teff(SpT) trend Teff(K6.5V) = 4200K ; non-standard GJ 146/HD 22496 Teff(K6.5V) = 4230K ; non-standard GJ 45/HD 5633 Teff(K6V) = 4230K ; K6V adopted => Teff(K6.5V) = 4190K (logT = 3.622); updated 5/18/2019 (B-V)(K6V) = 1.240 ; adopted (B-V)(K6.5V) = 1.30 ; median Hinkel17 (N=8, all Gray06!) (B-V)(K6.5V) = 1.312 ; Gray06 K6.5V stars (N=8; +-0.009 sem, +-0.030 rms) (B-V)(K6.5V) = 1.314 ; non-standard GJ 146 (B-V)(K6.5V) = 1.32 ; non-standard GJ 45/HD 5633 (B-V)(K6.5V) = 1.322 ; non-standard GJ 9646/HD 178445 (B-V)(K7V) = 1.330 ; adopted (B-V)(K6.5V) = 1.35 ; non-standard GJ 826.1/HD 203040 => adopt (B-V)(K6.5V) = 1.31 [updated 5/18/2018] (G-V)(K6V) = -0.50 ; adopted for K6V (G-V)(K6V) = -0.556 ; interp K6V(B-V=1.24,G-V=-0.50),K7V(B-V=1.34,G-V=-0.58) (G-V)(K6.5V) = -0.568 ; SIMBAD d<20pc trend for V-Ks=3.288 (G-V)(K7V) = -0.58 ; adopted for K7V => adopt (G-V)(K6.5V) = -0.56 [updated 11/1/2020] (Bp-Rp)(K6V)=1.58 ; K6V mean (Bp-Rp)(K7V)=1.71 ; K7V mean => adopt (Bp-Rp)(K6.5V)=1.64 [updated 3/1/2019] (G-Rp)(K6V)= 0.79; K6V mean (G-Rp)(K7V)= 0.87; K7V mean => adopt (G-Rp)(K6.5V) = 0.83 [updated 3/1/2019] => adopt (Bp-G)(K6.5V) = 0.81 [updated 3/1/2019; Bp-Rp=1.64, G-Rp=0.83] (V-Ks)(K6.5V) = 3.223 ; trend for K dwarf standards+exemplars (V-Ks)(K6.5V) = 3.252 ; non-standard GJ 146/HD 22496 (V-Ks)(K6.5V) = 3.303 ; non-standard GJ 9646/HD 178445 (V-Ks)(K6.5V) = 3.399 ; non-standard GJ 826.1/HD 203040 Mv(K6.5V) = 7.92 ; non-standard GJ 146/HD 22496 I've just interpolated properties here based on the properties of the better populated K6V and K7V types, adjusting for the mean B-V from the Gray06 K6.5V stars. #SpT Teff logT BCv Mv logL B-V Bt-Vt V-G U-B V-Rc V-Ic V-Ks J-H H-K Ks-W1 W1-W2 W1-W3 W1-W4 Msun logAge b-y M_J M_Ks Mbol i-z z-Y R_Rsun #SpT K6.5V 4190 3.622 -0.92 8.01 -0.96 1.310 1.491 0.672 1.213 0.796 1.505 3.288 0.613 0.159 0.055 ... ... ... 0.66 ... ... 5.56 4.78 7.09 ... ... 0.656 K6.5V # Non-standards GJ 146 = HD 22496 = LHS 1563 = HIP 16711 (J0335-4825; V=8.6) K5V: Luyten45(K5),Montes01 K5/M0V: Houk78 K5.9V: Houdebine16(dK5.9) *K6.5V(k): Gray06 K7V: Eggen61,Upgren72,Bidelman85(K7:) Median type is Gray06's K6.5V, mean is K6.2+-0.3. V=8.57(HIP), V=8.590+-0.032(Mermilliod91). B-V=1.314+-0.009(Mermilliod91), U-B=1.240(Mermilliod91). J=6.122+-0.020(2MASS), H=5.493+-0.029(2MASS), Ks=5.338+-0.018(2MASS). V-Ks = 8.59 - 5.338 = 3.252. Teff=4136+-12K(Franchini14), 4150+-100K(Houdebine16#2), Teff=4172K(Hinekl17), 4220+-50K(Houdebine#2), 4250K(Morales08), 4260K(Houdebine16#3) => ~ 4200K. [M/H]=0.11+-0.05(Franchini14), [Fe/H]=-0.25(Houdebine16). logL=-0.89(Hinkel17). VSX list it as variable star NSV 1203, with variability of 0.7 mag? B-V and V-Ks is close to mean for K6.5V. plx = 73.5244+-0.0387mas(GaiaDR2). Mv = 7.92+-0.03(Mermilliod91,GaiaDR2), within 0.1 mag of mean for K6.5Vs. GJ 9646 = Gl 747.3 = HD 178445 = HIP 94225 K5/M0V: Houk78 K6.0V: Houdebine16(dK6.0) *K6.5V: Gray06 K7V: Evans64,Upgren72,Bidelman85,Gliese91 V=9.36(HIP), V=9.363+-0.007(Mermilliod91), B-V=1.322+-0.017(Mermilliod91), U-B=1.245+-0.146(Mermilliod91). J=6.846+-0.021(2MASS), H=6.207+-0.024(2MASS), Ks=6.060+-0.024(2MASS), V-Ks = 9.363 - 6.060 = 3.303. Teffs: 4130+-100K(Houdebine16#1), 4170K(Morales08), 4180K(Houdebine16#3), 4203+-70K(Houdebine16#2) => = 4175K. [Fe/H] = -0.25(Houdebine16). GJ 826.1 = HD 203040 = LHS 3657 = StKM 2-1513 = UGP 520 K5V: Bidelman86 K5.1V: Houdebine16 K6V: Adams35 *K6.5Vk: Gray06 K7: Bidelman85 M0V: Vyssotsky46,Upgren72,Joy74 Mean published type K6.7+-0.4. V=9.12(Mermilliod91), B-V=1.35(Mermilliod91), U-B=1.26(Mermilliod91), J=6.541+-0.020(2MASS), H=5.905+-0.034(2MASS), Ks=5.721+-0.018(2MASS), V-Ks = 9.12 - 5.721 = 3.399. Teffs: 4030+-242K(Yee17), 4089K(Hinkel17), 4090+-100K(Houdebine16#1,#3), 4243+-111K(Houdebine16#2) => = 4090K. [Fe/H] = -0.28(Houdebine16), [Fe/H]=-0.05+-0.10(Yee17). GJ 45 = HD 5633 (J0057-6214) K5: Luyten79 K5.7V: Houdebine16(dK5.7) *K6.5V(k): Gray06 K7V: Evans66(K7Ve),Woolley70(K7),Gliese91 M0V: Upgren72,Houk75 V=9.482(Koen10), B-V=1.320(Koen10), U-B=1.256(Koen10), V-Rc=0.806(Koen10), V-Ic=1.493(Koen10), J=7.081+-0.026(2MASS), H=6.486+-0.036(2MASS), Ks=6.284+-0.020(2MASS), V-Ks = 9.482 - 6.284 = 3.198. Teffs: 3874K(Leger15), 4191K(Hinkel17), 4210+-100K(Houdebine16#1), 4250K(Morales08), 4252+-62K(Houdebine16#2), 4340K(Houdebine16#3) => 4230K. [Fe/H]=-0.25(Houdebine16).