G0V Garrison94 lists bet CVn as the G0V anchor type, and MK73 lists bet Com as the G0V dagger standard in Morgan's table (Table 1), and bet CVn and lam Ser as a secondary G0V standards in Keenan's part of the review (Table 2). bet CVn does appear to be the best primary standard, with continuity as "G0V" from JM53, MK73, KeenanMcNeil76, Keenan88, Keenan89. I would stay away from eta Cas as a standard as it is G0V according to Morgan, but F9V according to Keenan (right at the boundary between their respective classification regimes). bet CVn appears to have the best pedigree and agreement on G0V type over time. For a mapping of the Houk/MSS types to the modern MK grid (Keenan and Gray) for G dwarfs, see table at end of the file. HD catalog: bet Hyi - G0 (1918AnHar..91.....C) MK43 standard: xi UMa - G0V (but 1" binary with Keenan89 calls F8.5:V+G2V) JM53 standard: bet Com & eta Cas & bet CVn - G0V Morgan65 standard: bet CVn - G0V Morgan71 standard: bet Com - G0V Garrison72 standard: bet Com (= HD 114710) - G0V MK73 standard: bet Com (dagger) & bet CVn & lam Ser (secondary, non-dagger) - G0V MorganAbt73 standard: bet Com & eta Cas A - G0V Cowley76 standard: bet Com & eta Cas A - G0V KeenanMcNeil76 stan.: bet CVn, bet Com, eta Cas A - G0V MK78 standard: eta Cas - G0V Keenan80 standard: eta Cas A - G0V del Tri (=HD 13974) - G0V iot Per (=HD 19373) - G0V chi^1 Ori (=HD 39587) - G0V 47 UMa (=HD 96128) - G0V bet CVn (=HD 109358) - G0V lam Ser (=HD 141004) - G0-V 26 Dra (=HD 160269) - G0Va Keenan83 standards: eta Cas A - G0V iot Per (=HD 19373) - G0V chi^1 Ori (=HD 39587) - G0V bet CVn (=HD 109358) - G0V kap For (=HD 14802) - G0Va 26 Dra (=HD 160269) - G0Va lam Ser (=HD 141004) - G0-V Turnshek85 standard: bet CVn - G0V Keenan85 standards: eta Cas A - G0V bet CVn - G0V kap For (=HD 14802) - G0Va iot Per (=HD 19373) - G0V chi^1 Ori (=HD 39587) - G0V xi UMa B (=HD 98230B) - G0V lam Ser - G0-V 39 Ser (=HD 142267) - G0V Fe-0.5 rho CrB (=HD 143781) - G0+Va Fe-1 26 Dra (=HD 160269) - G0Va Corbally86 standard: HD 27406 (= vB 31) - G0V Keenan88 standards: chi2 Ori (=HD 39587) - G0-V Ca0.5 (typo, he says "Chi^1 Ori") 47 UMa (=HD 95128) - G0V bet CVn - G0V lam Ser - G0-V 26 Dra (=HD 160269) - G0IV-V Gray89 standard: kap For (=HD 14802) - G0V Keenan89 standards: chi2 Ori (=HD 39587) (pri. stan.) - G0V bet CVn - G0V (prim. stan.) iot Per - G0V (prim. stan.) chi1 Ori - G0V (prim. stan.) lam Ser - G0-V (prim. stan.) rho CrB - G0+ Va Fe-1 (prim. stan.) 26 Dra - G0IV-V (prim.stan.) Keenan99 standards: chi2 Ori (=HD39587) - G0V (prim.stan.) GrayAtlas standard: bet Com & eta Cas A - G0V GrayNstars standard: bet CVn - G0V, lam Ser - G0-V Keenan99 lists "Chi2 Ori" = HD 39587, however this is a typo (should be "Chi1 Ori", as listed in Keenan89. Mean color of Hipparcos G0V stars w/i 75 pc is 0.588 Mean color of Hipparcos G0IV stars w/i 75 pc is 0.586 (N=20) Mean color of Hipparcos G0III stars w/i 75 pc is 0.591 (N=6) (B-V)(G0V) = 0.510 ; BakisEker22 (G0V) = 0.62 ; G0V in Hyades Wilson62(N=1) (B-V)(G0V) = 0.603 ; Gray01/03/06 in xHIP d<50pc interp [Fe/H]=0.0 (G0V) = 0.60 ; Fitzgerald70 (B-V)(G0V) = 0.60 ; JohnsonMorgan53 (G0V) = 0.600 ; exemplar HD 105 (see below) (B-V)(G0V) = 0.60 ; median CATSUP d<30pc sample (N=18) (B-V)(G0V) = 0.60 ; tert. stan. kap For ([Fe/H] ~ -0.06) (G0V) = 0.599 (+-0.001 sem, +-0.018 stdev; Gray01/03/06 N=81) (B-V)(G0V) = 0.596 ; median SIMBAD G0V d<25pc (N=25) (B-V)(G0V) = 0.595 ; sec. stan. iot Per ([Fe/H] ~ +0.10) (B-V)(G0V) = 0.595 ; trend for 4 standard stars for [Fe/H], rms scatter only 0.003 mag) (B-V)(G0V) = 0.594 ; ter. stan. chi01 Ori ([Fe/H] ~ -0.04) (B-V)(G0V) = 0.590 (+-0.006 sem, +-0.023 stdev) med. of 38 ARICNS G0V stars (B-V)(G0V) = 0.59 ; Johnson66 (B-V)(G0V) = 0.59 ; Morgan71 (B-V)(G0V) = 0.588 ; prim. stan. bet CVn ([Fe/H] ~ -0.21) (G0V) = 0.585 (+-0.002 sem, +-0.025 stdev; HIP d<75pc S/N>8 N=233) (G0V) = 0.58 ; MorganAbt73/TableIII (B-V)(G0V) = 0.58 ; SchmidtKaler82, KenyonHartmann95 (B-V)(G0V) = 0.573 ; exemplar HD 50692 (G0V) = 0.57 ; Bessell79 (B-V)(G0V) = 0.57 ; Strassmeier90 (G0V) = 0.529 ; Crawford76 => adopt (B-V)(G0V) = 0.595 [updated 10/26/2020] [EEM 10/26/2020; see discussion at end, there is remarkably small scatter of only few mmag among the 4 standard stars as function of metallicity - value is interpolated to [Fe/H]=0.0] => adopt (U-B)(G0V) = 0.057 => adopt (V-I)(G0V) = 0.673 => adopt (V-R)(G0V) = 0.341 => adopt (R-I)(G0V) = 0.333 => adopt (V-J)(G0V) = 1.108 => adopt (V-H)(G0V) = 1.370 => adopt (V-Ks)(G0V) = 1.437 => adopt (H-Ks)(G0V) = 0.067 => adopt (J-H)(G0V) = 0.262 => adopt (K-W1)(G0V) = 0.058 (V-Ks)(G0V) = 1.428 (+-0.043) ; B-V vs. V-Ks for XHIP d<50pc G dwarfs (-0.1<[Fe/H]<0.1) for B-V=0.595 (Ks-W1)(G0V) = 0.058 ; EEM trend for d<30pc for B-V=0.596 => adopt (Ks-W1)(G0V) = 0.058 [updated 12/29/2019] (Bp-Rp)(G0V) = 0.7667 ; bet_CVn (Bp-Rp)(G0V) = 0.7691 ; chi01_Ori (Bp-Rp)(G0V) = 0.770 ; median for G>6.5 G0V(Gray types) w/i 40pc (N=27) (Bp-Rp)(G0V) = 0.7717 ; iot_Per (Bp-Rp)(G0V) = 0.781 ; field dwarf trend for B-V=0.595 (Bp-Rp)(G0V) = 0.794468 ; bet_CVn (pri. stan.) GaiaEDR3 (Bp-Rp)(G0V) = 0.8122 ; kap_For (Bp-Rp)(G0V) = 0.824 ; Evans18 trend for V-I= 0.673 => adopt (Bp-Rp)(G0V) = 0.77 [updated 11/15/2020] (Bp-G)(G0V) = 0.301629 ; bet_CVn (pri. stan.) GaiaEDR3 (Bp-G)(G0V) = 0.329 ; median for G>6.5 G0V(Gray types) w/i 40pc (N=27) (Bp-G)(G0V) = 0.33 ; Bp-Rp=0.77, G-Rp=0.44 (Bp-G)(G0V) = 0.344 ; field dwarf trend for B-V=0.595 (Bp-G)(G0V) = 0.3823 ; chi01_Ori (Bp-G)(G0V) = 0.3827 ; kap_For (Bp-G)(G0V) = 0.4019 ; bet_CVn (Bp-G)(G0V) = 0.4104 ; iot_Per => adopt (Bp-G)(G0V) = 0.33 [updated 11/15/2020] (G-Rp)(G0V) = 0.3614 ; iot_Per (G-Rp)(G0V) = 0.3648 ; bet_CVn (G-Rp)(G0V) = 0.3868 ; chi01_Ori (G-Rp)(G0V) = 0.4295 ; kap_For (G-Rp)(G0V) = 0.438 ; field dwarf trend for B-V=0.595 (G-Rp)(G0V) = 0.443 ; median for G>6.5 G0V(Gray types) w/i 40pc (N=27) (G-Rp)(G0V) = 0.492839 ; bet_CVn (pri. stan.) GaiaEDR3 => adopt (G-Rp)(G0V) = 0.44 [updated 11/15/2020] (G-V)(G0V) = -0.178 ; * e Vir G0V (G-V)(G0V) = -0.177 ; * w Her G0V (G-V)(G0V) = -0.171 ; * iot Pav G0V (G-V)(G0V) = -0.166+-0.008 ; ter. stan. kap For (G-V)(G0V) = -0.165 ; pri. stan. bet CVn [GaiaEDR3] (G-V)(G0V) = -0.162+-0.008 ; pri. stan. bet CVn (G-V)(G0V) = -0.159 ; HD 101177A PM* G0V (G-V)(G0V) = -0.159 ; HD 88742 PM* G0V (G-V)(G0V) = -0.157 ; * pi. Men G0V (G-V)(G0V) = -0.153 ; * 15 Sge G0V (G-V)(G0V) = -0.155 ; trend for polynomial fit to nearby dwarfs for (B-V)=0.595 (G-V)(G0V) = -0.155 ; G-dwarf trend for G0V (G-V)(G0V) = -0.148 ; HD 212168 PM* G0V (G-V)(G0V) = -0.148 ; HD 34721 PM* G0V (G-V)(G0V) = -0.146 ; HD 134060 PM* G0VFe+0.4 (G-V)(G0V) = -0.145 ; * 37 Gem G0V (G-V)(G0V) = -0.143 ; * iot Per G0V (G-V)(G0V) = -0.143 ; HD 52711 PM* G0V (G-V)(G0V) = -0.142 ; HD 124580 PM* G0V (G-V)(G0V) = -0.142+-0.008 ; sec. stan. iot Per (G-V)(G0V) = -0.139 ; * phi02 Pav G0VFe-0.8CH-0.5 (G-V)(G0V) = -0.138 ; * bet Hyi G0V => adopt (G-V)(G0V) = -0.155 [updated 11/1/2020] (U-B)(G0V) = 0.057 ; HIP d<75pc S/N>8 G1V N=133 (Mermilliod91 photometry) (U-B)(G0V) = 0.06 ; JohnsonMorgan53 (U-B)(G0V) = 0.11 ; Johnson66 [big discrepency!] (G0V) = 0.669 (+-0.001 sem, +-0.024 stdev; N=81) (G0V) = 0.658 (+-0.001 sem, +-0.025 stdev; HIP d<75pc S/N>8 N=233) (G0V) = 0.625 ; Bessell79 (G0V) = 0.303 ; Bessell79 (G0V) = 1.086 (+-0.005 sem, +-0.065 stdev; HIP d<75pc S/N>8 N=233) (G0V) = 1.342 (+-0.006 sem, +-0.087 stdev; HIP d<75pc S/N>8 N=233) (G0V) = 1.422 (+-0.008 sem, +-0.086 stdev; HIP d<75pc S/N>8 N=233) (G0V) = 0.259 (+-0.002 sem, +-0.035 stdev; HIP d<75pc S/N>8 N=233) (G0V) = 0.079 (+-0.002 sem, +-0.026 stdev; HIP d<75pc S/N>8 N=233) (G0V) = 0.638 (+-0.003 sem, +-0.036 stdev; HIP d<75pc S/N>8 N=233) (G0V) = -0.066 (+-0.001 sem, +-0.013 stdev; HIP d<75pc S/N>8 N=233) (G0V) = 2.007 (+-0.007 sem, +-0.104 stdev; N=219) (g-r)(G0V) = 0.442 ; Jordi06 (V-R)=>(g-r) for V-R=0.343 (g-r)(G0V) = 0.423 ; Bilir05 (B-V)=>(g-r) for B-V=0.596 (g-r)(G0V) = 0.38 ; Covey07 => adopt (g-r)(G0V) = 0.42 [updated 10/10/2020] Teff(G0V) = 5844 +- 66 K ; vanBelle09 Teff(G0V) = 5860 K ; GrayCorbally94 Teff(G0V) = 5865 K ; ter. stan. kap For ([Fe/H] = -0.07, see below) Teff(G0V) = 5878 K ; pri. stan. beta CVn ([Fe/H] = -0.20, see below) Teff(G0V) = 5895 K ; median photometric Teff Teff(G0V) = 5900 K ; GrayCorbally09 Teff(G0V) = 5900 K ; median of Valenti05 Teffs for 43 G0V stars from Gray03/06 Teff(G0V) = 5913 K ; exemplar HD 50692 (37 Gem) [Fe/H]=-0.105 Teff(G0V) = 5924 K ; Valenti05 trend for G0V [M/H]=0 (Gray03/06 SpTs) Teff(G0V) = 5934 K ; Gray03/Gray06 Teff trend for G0V [M/H]=0 star. Teff(G0V) = 5935 K ; Teff from smoothed SpT(Teff) trend Teff(G0V) = 5937 K ; Teff for d<30pc [Fe/H]=+-0.1 dex dwarfs from Hinkel17 for B-V=0.596 Teff(G0V) = 5943 K ; ter. stan. chi01 Ori ([Fe/H] = -0.03; see below) Teff(G0V) = 5952 K ; sec. stan. iot Per ([Fe/H] = +0.09; see below) Teff(G0V) = 5973 K ; Boyajian12 Teff(G0V) = 6000 K ; Bessell79 Teff(G0V) = 6010 K ; Blackwell80 Teff(G0V) = 6030 K ; Schmidt-Kaler82 => adopt Teff(G0V) = 5930 K (logT = 3.773) [last updated 10/10/2020] BCv(G0V) = -0.046 mag ; Balona94(Teff=5930K) BCv(G0V) = -0.049 mag ; Bertone04(Teff=5930K) BCv(G0V) = -0.050 mag ; Schmidt-Kaler82(BCv=-0.18 + 0.13 offset) BCv(G0V) = -0.059 mag ; Flower96(Teff=5930K) BCv(G0V) = -0.063 mag ; Masana06(Teff=5930K) BCv(G0V) = -0.063 mag ; EEM fit to Casagrande06/08/10(Teff=5930K) BCv(G0V) = -0.065 mag ; Casagrande18(Teff=5930K,logg=4.5) BCv(G0V) = -0.066 mag ; Bessell98(ATLAS9,logg=4.5,Teff=5930K) BCv(G0V) = -0.066 mag ; Code76(Teff=5930K) => adopt BCv(G0V) = -0.065 mag ; [last updated 10/10/2020, on scale where BCv(5772K)=-0.085] Mv(G0V) = 4.72 mag ; ter. stan. HD 39587 = chi01 Ori Mv(G0V) = 4.59 mag ; pri. stan. bet CVn = HD 109358 Mv(G0V) = 4.56 mag ; exemplar HD 50692 Mv(G0V) = 4.53 mag ; exemplar HD 105 Mv(G0V) = 4.53 mag ; V-Ks=1.44 for EEM poly fit to SIMBAD d<25pc (1/2022) (M_Ks=3.09) Mv(G0V) = 4.51 mag ; CATSUP -0.1 < [Fe/H] < 0.1 d<30pc for B-V=0.596 Mv(G0V) = 4.50 mag ; B-V=0.595 => EEM fit to SIMBAD dwarfs d<25pc Mv(G0V) = 4.48 mag ; xHIP |[Fe/H]|<0.2 dex d<25pc dwarf only for B-V=0.595 Mv(G0V) = 4.47 mag ; linear fit to Gray01/03/06 dwarf sequence (d<50pc) for B-V=0.596 Mv(G0V) = 4.47 mag ; median XHIP G0V d<20pc Mv(G0V) = 4.46 mag ; Gray01/03/06 dwarfs, xHIP B-V/Mv, Gaspar16 |[Fe/H]|<0.05 "solar": fit for B-V=0.596 Mv(G0V) = 4.44 mag ; B-V=0.596 => Mv(Wright05) Mv(G0V) = 4.4 mag ; Schmidt-Kaler82 Mv(G0V) = 4.4 mag ; GrayCorbally09 Mv(G0V) = 4.35 mag ; median SIMBAD G0V d<25pc (N=25) Mv(G0V) = 3.94 mag ; sec. stan. iot Per = HD 19373 Mv(G0V) = 3.76 mag ; Wegner07 Mv(G0V) = 3.41 mag ; ter. stan. HD 14802 = kap For => adopt Mv(G0V) = 4.48 mag [updated 10/31/2020] => adopt M_G(G0V) = 4.325 mag [updated 12/10/2020] (Mv=4.48, G-V=-0.155) => adopt M_Ks(G0V) = 3.043 mag [updated 12/30/2020] (Mv=4.48, V-Ks=1.437) logL(G0V) = 0.130 dex ; Mv=4.48, BCv=-0.065 => Mbol = 4.415 => adopt logL(G0V) = 0.130 dex [last updated 10/30/2020] => adopt Mbol(G0V) = 4.415 mag [last updated 10/30/2020] Rad(G0V) = 1.1004 Rsun ; Teff=5930K, logL=0.130 => adopt Rad(G0V) = 1.100 Rsun [updated 10/30/2020] Mass(G0V) = 1.028 Msun ; Bertelli09 solar tracks Teff=5930K,logL=0.122 Mass(G0V) = 1.061 Msun ; Ekers18 ML calibration for logL=0.122 Mass(G0V) = 1.061 Msun ; EEM fit to Torres10 binaries for Mv=4.5 Mass(G0V) = 1.071 Msun ; EEM logL vs. Mass fit (logL=0.122) Mass(G0V) = 1.120 Msun ; HenryMcCarthy93 fit for Mv=4.5 Mass(G0V) = 1.182 Msun ; EEM Teff vs Mass fit (Teff=5930K) => adopt Mass(G0V) = 1.06 Msun [updated 12/29/2019] logg(G0V) = 4.35 ; median for 44 Gray03/Gray06 G0V stars with Valenti05 logg # No standard Houk75 does not list a G0V standard. Houk mentions Bet Com was listed as a G0V standard by MK73, but MK73 was only published when they were half way done with Volume 1 (1975). Instead, Houk considered Bet Com to be a G2V standard. Hence, among the early Gs, it is possible that Houk's stars are ~2 subtypes later than what Morgan/Keenan would adopt. # Primary Standard bet CVn = HD 109358 = HR 4785 = GJ 475 *G0V: MKK43,JM53,Morgan65,Garrison72(stan),MK73,KeenanMcNeil76(stan),Jaschek78,Keenan85,Turnshek85(stan),Keenan88,Garrison94,Gray01,Gray03,GrayNstars G1V: MorganAbt73 B-V=0.585+-0.005(Mermilliod91), B-V=0.586(Jerzykiewicz66), B-V=0.587(Just08), B-V=0.588+-0.009(HIP), B-V=0.59(Johnson66), B-V=0.593+-0.002(Tycho) => adopt B-V=0.588. V=4.260+-0.007(Mermilliod91), U-B=0.046+-0.011(Mermilliod91). PASTEL mean values (Soubiran22): Teff=5878+-14K(N=38), logg=4.42+-0.02(N=26), [Fe/H]=-0.20+-0.01(N=28). plx = 116.1298 +- 0.6776 mas (GaiaDR2), plx= 118.0266+-0.1530(GaiaEDR3). Mv=4.59(HIP,GaiaDR2). GaiaDR2 photometry, G corrected, Bp and Rp OK. G = 4.0147+-0.0047 (GaiaDR2, uncorrected), G(corr)=4.098, Bp-Rp = 0.7667, Bp-G = 0.318(corr), G-Rp = 0.448(corr). G-V=-0.162+-0.008(corr). GaiaEDR3: G=4.094672 0.003013, E(BP/RP)=1.212, Bp-Rp=0.794468, Bp-G=0.301629, G-Rp=0.492839. G-V=4.095-4.26 = -0.165(GaiaEDR3,Mermilliod91). # Secondary Standard iot Per = HD 19373 = HR 937 = Cl Melotte 20 44 F9.5V: Adams38,Gray03 *G0V: 1937ApJ....85..380M,MK43,Heckman56(G0),1961UppAn...4j...1L,Keenan80,Keenan85,Keenan89(stan) G0IV-V: Gray01 G1V: Adams35,1956AN....283..109H,Bidelman85(G1) G2V: Moore50 Continuity in use by Keenan from MK43 through Keenan89, and Gray keeps at same subtype. B-V=0.590(Argue66), B-V=0.595+-0.007(Mermilliod91,HIP), B-V=0.60(Johnson66), U-B=0.118+-0.010(Mermilliod91), V=4.049+-0.007(Mermilliod91). PASTEL mean values (Soubiran22): Teff=5952+-12K(N=35), logg=4.22+-0.02(N=19), [Fe/H]=+0.09+-0.01(N=23). plx = 95.1587 +- 0.3021mas(GaiaDR2). GaiaDR2 photometry, G and Rp needed correction: G(corr)= 3.907, Bp(corr)= 4.226, Rp(corr)= 3.446, (Bp-Rp)(corr)= 0.780, (Bp-G)(corr)= 0.319, (G-Rp)(corr)= 0.461. G-V = 3.907 - 4.049 = -0.142+-0.008. Mv = 3.94(HIP,GaiaDR2). logg and Mv seems somewhat evolved. # Tertiary Standards HD 14802 = kap For = HR 695 = GJ 97 F5: Cannon *G0V: Keenan85(G0Va),Keenan89,Gray89,Keenan99,Gray06 G1V: Jaschek78(Buscombe62),Torres06 G2V: Houk88 Torres06 says SB? Was only other G0V star besides the primary standard chi2 Ori listed in Keenan's final list (Keenan99, but was only complete to RA=11:03). I would consider it a tertiary standard given the lack of agreement among other classifiers besides Keenan. This one also demonstrates the differences between Keenan's and Houk's early G sequence - Keenan calls G0, Houk calls G2. B-V=0.597+-0.004(Mermilliod91), B-V=0.60(Johnson66), B-V=0.608+-0.017(HIP), B-V=0.612+-0.004(TYC) => adopt (B-V)=0.597. V=5.190+-0.007(Mermilliod91), U-B=0.120+-0.161(huge error!). PASTEL mean values (Soubiran22): 5865+-20K(N=10), logg=4.03+-0.04(N=9), [Fe/H]=+0.07+-0.02(N=9). plx = 44.0905 +- 0.2799mas(GaiaDR2). GaiaDR2, only G needed to be corrected following Evans18: G(corr)= 5.024, Bp= 5.366, Rp= 4.553, (Bp-Rp)= 0.812, (Bp-G)(corr)= 0.341, (G-Rp)(corr)= 0.471. G-V = 5.024 - 5.190 = -0.166+-0.008. Mv = 3.412(HIP,GaiaDR2). HD 39587 = chi01 Ori = HR 2047 = HIP 27913 F8V: Moore50 F9V: Adams35 G0-V Ca0.5: Keenan88 *G0V: 1927MeUpp..28....1L,Morgan38,MK43,Roman52,Slettebak55,Keenan80,Keenan85,Bidelman85(G0),Keenan89,Keenan99 G0IV-V: Gray03(G band slightly weak) G0V CH-0.3: Gray06 G1V: Cowley76,Levato78 Ursa Major group member, so probably ~0.4 Gyr old (also logR'HK = -4.54; Brewer16). I only consider it tertiary as there have been some spectral flags mentioned, however this is puzzling as Brewer16 shows the star to have very solar abundance pattern: [M/H]=0.04, [C/H]=0.02, [N/H]=0.00, [O/H]=0.07, [Fe/H]=0.08. So it is a bit puzzling to explain the "G band slightly weak" comment from Gray03 and CH-0.3 flag from Gray06. A warning that "Chi02 Ori" is a V=4.6 B2 supergiant! V=4.39(HIP), V=4.404+-0.009(Mermilliod91), V=4.41(Johnson66), B-V=0.589+-0.008(Mermilliod91), B-V=0.59(Johnson66), B-V=0.594+-0.008(HIP), B-V=0.597+-0.003(TYC), U-B=0.065+-0.009(Mermilliod91). PASTEL compendium averages (Soubiran22): Teff=5943+-12K(N=34), logg=4.46+-0.02(N=26), [Fe/H]=-0.03+-0.01(N=29). Ramirez13 lists precise values near the medians: Teff=5949+-64K, logg=4.48+-0.03, [Fe/H]=-0.04+-0.04. Hence the star appears to be ~solar metallicity and ~solar surface gravity. plx = 113.1240+-0.3178 mas (GaiaDR2), plx = 115.43+-0.27 mas (vanLeeuwen07). Mv = 4.72(HIP,vanLeeuwen07). Binary with M dwarf companion B at separation 0.5" (P=14.12yr). Koenig02 measures companion H=7.70+-0.15 at sep=0.4976", and estimates masses of 1.02+0.08 & 0.15+-0.01 Msun (so spectral type should be ~M5V?). Han & Gatewood(2002) estimate P=5156.291d(14.12yr). # Depricated Standards (alas, there are many!) HD 114710 = bet Com = HR 4983 = GJ 502 *F9.5V : KeenanYorka85,Keenan89(prim.stan.) G0V : Maury1897(G0IV/V),Adams35,MK43,JM53,Morgan71,MK73(dagger),Cowley76(stan),KeenanMcNeil76(stan),Bidelman85(G0),Gray01,GrayAtlas G2V : Houk(changed, but she doesn't recommend use as a standard) Appears to be a common G0V standard among Morgan,Keenan & Gray, but not Houk. Houk acknowledges that her late Fs and early Gs might be earlier than that for the MK73 system, and one can see one of the reasons for the offset if she considered this F9.5V or G0V star as a G2V. Keenan89 called it a "F9.5V" primary standard! B-V=0.572+-0.006 (HIP). PASTEL: Teff = 5999+-21K(N=38), HD 4614A = eta Cas A = HR 219A = HIP 3821 = GJ 34A *F9V: Keenan88,Keenan89,Hoffleit91,Keenan99,Gray01,GrayNstars,Abt08 G0V: MK43,Moore50,JM53,Barry70(G0Vb),MorganAbt73,Cowley76(stan),KeenanMcNeil76(stan),MK78(stan),Abt81,Keenan83,Keenan85,GrayAtlas,Garrison96 B-V(HIP)=0.587, Vmag=3.46, Mv=4.59, dMv=+0.20, par=168.0+-0.4 mas. Spectroscopic binary; not in Houk. Probably inappropriate as standard as G0V mostly in ~1940s-80s. Garrison96 lists eta Cas A as the only G0V star among the brightest ~300 stars in the sky with V<3.55mag. Gray calls it G0V in his atlas, but F9V in his 2001 catalog. It appears G0V is where "MK" had an "M" version and a "K" version?. KeenanMcNeil76 and MK78 agree on using eta Cas as a "G0V" standard. Keenan had it as G0V in MK43, KeenanMcNeil76, Keenan83, and Keenan85 *but* changed it to F9V in Keenan88, Keenan89, Keenan99. I would recommend this star is never used as a standard given its inconsistent use by expert classifiers. del Tri = HR 660 = HD 13974 G0V: Maury1897(G0IV/V),Adams35,Keenan41,MK43,Ljunggren61,Keenan80,Bidelman85(G0),Gray01 G0.5V: Keenan83 *G0.5V Fe-0.5: Keenan89 F9V: Abt85 One of the G0V standards with the longest history and continuity, but Keenan89 switched subtype in his last compilation. Teff=5920K(Gray01), logg=4.31(Gray01), [M/H]=-0.21(Gray01), E(b-y)=0.02(Gray01). PASTEL compilation shows that most metallicity estimates are between [Fe/H] ~ -0.5 and -0.2, so clearly metal poor. WDS shows is tight binary. HD 27406 = Cl Melotte 25 31 = V986 Tau = HIP 20237 G0V: Perraud62,Morgan65,Corbally86(stan,Morgan65),Fehrenbach96 *F9V+: Gray01, Wilson48(F9) F8: HD, Adams35(F8V) One of the two G0V Hyads classified by Morgan65, and adopted as a G0V standard by Corbally86, however Gray01 calls it F9V+. HD 95128 = 47 UMa = HR 4277 G0V: HD(G0),Adams35,MK43,Roman50,Keenan80,Bidelman85,Keenan88 G1V: Gray01 *G1-V Fe-0.5: Keenan89,Keenan99 Was G0V standard in 1943 MKK atlas, but then Keenan changed mind in 1980s to make it a bit later. HD 141004 = lam Ser = HR 5868 = GJ 598 G0V: Adams35,Moore50,MK73 *G0-V: Keenan80,Keenan85,Keenan88,Keenan89 G0IV-V: Gray03 G0.5V: Stebbins57 G1: Bidelman50 G2V: MK43 I would prefer not to consider a star a standard if Keenan changed the classifications 3 times. Hard to believe was G2V in MK43, then swtiched to G0V by MK73! B-V = 0.604+-0.008 (HIP). rho CrB = HD 143761 = HR 5968 F8V: 1957ArA.....2...55O *G0+Va Fe-1: Keenan85,Keenan89(stan) G0V: 1927MeUpp..28....1L,Adams35,Hagan67,Gray01,Gray06 G0IV: Cowley76 G1: Bidelman85 G2V: Roman52(lines weak),Roman55,Harlan81 HD 160269 = 26 Dra = HR 6573 F9V+K3V: Edwards76 G0: Bidelman85 G0IV-V: Keenan89(stan) *G0V: Cowley67,Keenan80(G0Va),Abt81,Keenan85(G0Va),Christian01 G1V: Adams35,Johnson53 G2V: Roman50,Cowley76(G2V::) WDS has it as 0.6" binary, which may cuts its desirability as a standard. WDS: mag1=5.28, mag2=8.54. Edwards76 calls the pair F9V+K3V. Keenan89 was only one that had IV-V. Using HIP2 parallax, Mv=4.47, which is right on main sequence for B-V=0.602. PASTEL compendium: = 5933K(N=8), = 4.42(N=7), [Fe/H]=-0.04(N=7). So the star is a ~solar metallicity, ~solar surface gravity. # Exemplars HD 50692 = 37 Gem = HR 2569 = 2MASS J06551867+2522320 *G0V: Adams35, 1953UppAn...3h....W, Harlan69, Cowley79, Clausen79, Gray03 All N=6 Skiff compendium references have G0V classification! V=5.74(HIP), B-V=0.573+-0.010(HIP), B-V=0.570+-0.014(Mermilliod91). Mv = 4.56(HIP,HIP2). Candidate standard? PASTEL compendium: =5913K(N=9), <[Fe/H]>=-0.105(N=9), =4.42(N=9). HD 105 = HIP 490 = 2MASS J00055255-4145109 *G0V: Evans57, Houk78, Stocke91(G0Ve), Torres06 Chromospherically active nearby young star in ~40 Myr-old Tuc-Hor association. PASTEL compendium has 4 Teff estimates + Pecaut13 has another (Teff=5990+-16 K), overall median Teff ~ 6045K), and two metallicity estimates ([Fe/H] = 0.02+-0.04 Tsantaki14, [Fe/H] = 0.08+-0.03 Valenti05), so near solar. V = 7.513+-0.005(Mermilliod91), B-V=0.600+-0.000(Mermilliod91). J=6.464+-0.020(2MASS), H=6.189+-0.023(2MASS), Ks=6.117+-0.020(2MASS), V-Ks = 1.396(Mermilliod91,2MASS). Mv=4.53(HIP,HIP2). Morgan65 classified two Hyads as G0V: HD 27406 (B-V=0.560; see above among deprecated standards) & 27691. They have B-V colors of 0.560 & 0.518, respectively (median B-V ~ 0.54). Oddly, Morgan65's F8V stars had almost identical median B-V ~ 0.55. # Other Stars HD 43587 F9V: Adams35,Cowley79 *G0V: Harlan74,Gray03,Gray06 G0.5Vab: Barry70 # B-V vs. Mv COLOR-MAG SEQUENCE F4V-G2V B-V vs. Mv linear fit: Mv = 0.387 + 6.827731*(B-V) 0.412 < B-V < 0.65 So stars with [Fe/H] within 0.05 dex of solar in Gaspar16, with [Fe/H] errors of <=0.05 dex, with dwarf luminosity class (V) in Gray01/03/06 studies, I find the following color-mag trend: 0.37 (~F2V) < B-V < 1.05 (~K3.5V) Mv = -0.50015894191808496 + 10.171262192637201*(B-V) - 3.1160587447998815*(B-V)^2 (rms=0.20mag) # TEFF-METALLICITY DEPENDENCE FOR "G0V" stars From the Gray03 and Gray06 NStars surveys, I extracted 77 stars that had "G0 V" types. I retained those that had peculiarity flags afterwards (e.g. "Fe-0.8") as I wanted stars with a wide range of chemical compositions for a given Balmer/Teff subtype. Using the Gray03/Gray06 Teffs and [M/H] values, the following trends are present: Teff = 5934 K + 140.339*[M/H] ; rms = 80K Cross-referencing this list with the ValentiFischer05 catalog, there are 45 matches, and I find these trends: Teff = 5924 K + 133.930*[M/H] ; rms = 55 K range (-0.39 < [M/H] < 0.26) (B-V) = 0.599 - 1.348869e-4*(Teff - 5900K) ; rms = 0.0186 Teff = 5910 K - 1109.704*(B-V - 0.599) ; rms = 53 K So the lesson seems to be that even for G0V stars with [M/H] ~ -0.2 or +0.2, this only translates to systematic shifts of +-27K in Teff (unresolvable given typical errors). Querying the Gray G0V stars through xHIP for d<50pc (for [Fe/H] errors <0.1 dex, (B-V) errors <=0.01), I find: (B-V) = 0.6036 + 0.0192*[Fe/H] (rms=0.013) Here are the stars with Gray03/Gray06 "G0 V" spectral types (some have peculiarities and chemical flags) and ValentiFischer05 catalog data: #Name Teff logg [M/H] B-V uB-V HIP_1444 5952 4.42 -0.04 0.599 0.004 HIP_2021 5873 4.08 -0.09 0.618 0.008 HIP_3170 6014 4.23 -0.21 0.564 0.016 HIP_3559 5839 4.10 -0.18 0.603 0.009 HIP_13902 5874 4.37 -0.20 0.590 0.008 HIP_15371 5845 4.54 -0.23 0.600 0.009 HIP_22905 5879 4.39 -0.16 0.606 0.015 HIP_24205 5904 4.43 -0.12 0.588 0.016 HIP_26394 5950 4.36 0.04 0.600 0.003 HIP_27244 5995 4.40 0.01 0.594 0.009 HIP_27913 5882 4.34 0.00 0.594 0.008 HIP_29673 6022 4.32 -0.16 0.562 0.007 HIP_29860 5892 4.33 -0.08 0.610 0.000 HIP_32322 5937 4.31 -0.39 0.550 0.021 HIP_33277 5891 4.36 -0.13 0.573 0.010 HIP_34017 5889 4.41 -0.10 0.595 0.008 HIP_34065 5827 4.44 -0.15 0.624 0.009 HIP_39710 5838 4.45 -0.18 0.600 0.004 HIP_42291 5959 4.41 0.09 0.598 0.004 HIP_49769 5837 4.10 -0.13 0.615 0.009 HIP_50075 5949 4.41 -0.04 0.592 0.001 HIP_54400 5865 4.41 -0.17 0.606 0.009 HIP_59143 5977 4.27 0.12 0.613 0.002 HIP_61317 5930 4.44 -0.10 0.588 0.009 HIP_64459 5821 4.14 -0.20 0.591 0.008 HIP_66047 5964 4.35 0.00 0.603 0.010 HIP_67246 5873 4.23 0.12 0.630 0.006 HIP_74273 5914 4.37 0.08 0.623 0.003 HIP_77760 5861 4.14 -0.39 0.563 0.014 HIP_78459 5823 4.36 -0.14 0.612 0.003 HIP_79862 5884 4.40 -0.02 0.631 0.009 HIP_80399 6006 4.10 0.08 0.625 0.126 HIP_98819 5932 4.45 0.02 0.600 0.005 HIP_98819 5932 4.45 0.02 0.600 0.005 HIP_100017 5886 4.48 -0.11 0.602 0.004 HIP_101983 6040 4.02 -0.32 0.544 0.022 HIP_102125 5948 4.38 0.26 0.620 0.015 HIP_106213 5971 4.34 0.01 0.596 0.004 HIP_107350 5974 4.47 -0.01 0.587 0.003 HIP_107649 5889 4.42 -0.04 0.601 0.003 HIP_108736 5901 4.42 -0.13 0.572 0.011 HIP_110712 5897 4.33 -0.04 0.599 0.002 HIP_113044 5999 4.15 0.21 0.621 0.005 HIP_114424 5900 4.35 0.06 0.604 0.000 For the 4 well-characterized standard stars: [Fe/H] B-V -0.21 0.588 bet_CVn -0.04 0.594 chi01_Ori -0.06 0.597 kap_For +0.10 0.595 iot_Per (B-V) = 0.5947 + 0.0223*[Fe/H] (rms = 0.0032 mag; remarkably small scatter!) recommend adopting (B-V)=0.595 for solar metallicity # Mapping of Houk/Michigan Spectral Survey Types to Modern MK Grid (Gray/Keenan) for G Dwarfs See section 4.1 of Pecaut & Mamajek (2016) for a discussion on the subtle differences between specral classifications for dwarfs between the Michigan Spectral Survey catalog (Houk et al.) and those classified by Gray and collaborators on the modern MK grid (MK78 for hot stars through late F, Keenan standards for late F through M): https://ui.adsabs.harvard.edu/abs/2016MNRAS.461..794P/abstract . For the G dwarfs, PecautMamajek16 estimate the following mapping of types: SpT(Houk) SpT(Gray) F8/G0V => F9V G0V => F9.5V G0/1V => F9.5V G0/2V => G3:V G1V => G0+V G1/2V => G0V G2V => G0.5V G2/3V => G1V G3V => G1.5V G3/5V => G4V G5V => G4.5V G5/6V => G6V G8V => G8.5V K0V => K0V