FF2III HR 7222 is probably the best standard southernly accessible for F2III MK43 standard: bet Cas - F2III ups UMa - F2III JM53 standard: 14 Ari - F2III 16 Per - F2III Cowley69 standard: 14 Ari - F2III 16 Per - F2III MorganAbt72 standards: HR 7222 - F2III bet Cas (=HR 21) - F2III-IV MK73 dagger standard: bet Cas - F2III-IV Houk standard: 14 Ari - F2III [from JM53] Cowley76 standard: 16 Per - F2III HR 7222 - F2III MK78 standard: bet Cas - F2III-IV GrayGarrison89 standard: bet Cas - F2III(low vsini) GrayNstars standards: bet Cas - F2III HR 7222 - F2III GrayCorbally10 standard: bet Cas - F2III(low vsini) (J-H)(F2III) = 0.120 (+-0.027 sem, +-0.070 stdev) ; N=5 F2III from Skiff compendium w/i 15 deg of NGP w/q=AAA 2MASS photometry (J-H)(F2III) = 0.130 ; smoothed relation from giants in Skiff compendium w/i 15 deg of NGP, 2MASS photometry AAA flags => adopt (J-H)(F2III) = 0.130 [updated 10/30/2020] (H-Ks)(F2III) = 0.067 (+-0.016 sem, +-0.042 stdev) ; N=5 F2III from Skiff compendium w/i 15 deg of NGP w/q=AAA 2MASS photometry (H-Ks)(F2III) = 0.064 ; smoothed relation from giants in Skiff compendium w/i 15 deg of NGP, 2MASS photometry AAA flags => adopt (H-Ks)(F2III) = 0.064 [updated 10/30/2020] (B-V)(F2III) = 0.283 ; prim. stan. HR 7222 (B-V)(F2III) = 0.332 ; HIP 54182 F2III 2001AJ....121.2148G (B-V)(F2III) = 0.38 ; prim. stan. bet Cas (B-V)(F2III) = 0.379 (+-0.013 sem, +-0.041 rms) ; 19 F2III HIP stars w/i 75pc (B-V)(F2III) = 0.380 ; HIP 746 F2III 2003AJ....126.2048G => adopt (B-V)(F2III) = 0.38 [updated 10/30/2020] Mv(F2III) = 1.16 ; prim. stan. bet Cas Mv(F2III) = 1.19 ; prim. stan. HR 7222 Mv(F2III) = 2.31 ; HIP 54182 F2III 2001AJ....121.2148G => adopt Mv(F2III) = 1.2 [updated 10/30/2020] Teff(F2III) = 6900K ; prim. stan. bet Cas Teff(F2III) = 7050K ; prim. stan. HR 7222 => adopt Teff(F2III) = 7000K [updated 10/30/2020] # Primary Standards bet Cas = HD 432 = HR 21 = HIP 746 (J0009+5908; V=2.3) F2IV: JM53,Jaschek64(most),Cowley67 F2III-IV: Morgan72,MK73(dagger),MK78(stan) *F2III: MK43,Gray89,GrayGarrison89(low vsini stan.),Gray01,Gray03(stan),GrayNstars F5: Cannon Adopt "F2III (low vsini)" from GrayGarrison89. All published classifications since 1935 are "F2" subtype. Morgan flipflopped on luminosity class ("III" in MK43, "IV" in JM53, "III-IV" in MK73 and MK78). Gray has consistently called it "F2III" in four publications, and considers it the "F2III" standard, which I adopt. V=2.28(HIP), B-V=0.380+-0.004(HIP), V-I=0.40+-0.03(HIP), plx=59.58+-0.38mas (HIP2), close enough we can assume negligible reddening. Mv = 1.16+-0.02 mag. Teff = 6792K(Erspamer03), 6810K(Prugniel07#1), 6895K(Marsakov95), 6959K(Casagrande11), 7199K(Prugniel07#2) => adopt Teff=6900K. logg=4.09(Prugniel07), logg=3.59(Erspamer03). [Fe/H]=-0.10(PRugniel07), -0.15(Erspamer03). Age: 1.0 Gyr (Marsakov95) HR 7222 = HD 177392 = HIP 93603 (J1903+2116; V=6.5) *F2III: Harlan69,MorganAbt72(stan),Cowley76(standard),Penich81(metal weak),GrayNstars F1Vn: Gray01 Adopt "F2III" from MorganAbt72. Using revised Hipparcos parallax (plx = 8.73+-0.48 mas), I estimate Mv=1.32, and the star is 1.36 magnitudes above the main sequence. This would place it intermediate between the "III" and "IV" absolute magnitudes for F2. V=6.61(HIP), B-V=0.323+-0.004(HIP), V-I=0.37+-0.01(HIP), plx=8.73+-0.48 mas (HIP2). Reddening: E(b-y)=0.031 (Philip80), E(b-y)=0.03(Gray01). Adopting E(b-y)=0.03, then E(B-V)/E(b-y)=1.335 from Lallemont14, then E(B-V)=0.04 mag. Hence (B-V)o=0.323-0.04 = 0.283 mag. For R=3.33 appropriate for early F star, Av = 0.13 mag. Including this extinction, then Mv = 1.19+-0.12 mag. Teffs: 7050K (McDonald12). 16 Per F2III: Cowley76(standard)