FF7V Garrison94 does not list an F7V anchor standard, and MK73 does not list an MK73 dagger standard. None of the standards is particularly great, at least in terms of representing a near solar-metallicity F7V that is close to the color-mag main sequence. tet Per is worthy of some follow-up to see if it is truly halfway between F6V and F8V -- but its [Fe/H], Mv, and B-V are suggestive that it might be very representative of ~solar metallicity F7V stars (i.e. might be the best candidate standard of the bunch). iot Psc (= HD 222368) probably has the best pedigree of the F7V standards, however it appears to be slightly metal poor. JM53 standards: iot Psc - F7V tet Boo - F7V tet Per - F7V chi Dra - F7V Houk75 standard: iot Psc - F7V (primary standard) Cowley76 stardards: tet Boo - F7V HR 3794 - F7IV-V Houk/Michigan classifications: Houk's Michigan Spectral Survey catalogued 2370 stars as "F7V". Of these, 42 were later classified by Gray and collaborators (2001, 2003, 2006) with the median subtype being F8V (clipped mean F7.6 +-0.2 s.e.m., +-1.2 st.dev.). About a third of the Houk F8V stars were classified as stars of later hydrogen type with metal poor flags by Gray et al. (e.g. F8 through G0 with Fe and CH flags; the latest being "G0V Fe-0.8 CH-0.5"). I recommend grouping Houk's F7V stars with F7.5Vs classified since the 1970s (e.g. Gray's). Note that the median Teff of stars classified by Houk as F7V in the PASTEL compilation of Teffs (530 values) is 6208 K (+-168 K 1sigma scatter). For F7V Hipparcos stars within 75pc, with parallax S/N > 8, and within 1 mag of the MS (N=184): (F7V) = 0.989 (+-0.005 sem, +-0.053 stdev; N=184) (F7V) = 1.217 (+-0.006 sem, +-0.076 stdev; N=184) (F7V) = 1.290 (+-0.005 sem, +-0.083 stdev; N=184) (F7V) = 0.226 (+-0.003 sem, +-0.036 stdev; N=184) (F7V) = 0.072 (+-0.002 sem, +-0.026 stdev; N=184) (F7V) = 0.556 (+-0.003 sem, +-0.032 stdev; N=184) (F7V) =-0.060 (+-0.001 sem, +-0.010 stdev; N=184) (F7V) = 1.819 (+-0.010 sem, +-0.102 stdev; N=192) (B-V)(F7V) = 0.535 ; median CATSUP d<30pc (N=4; wide dispersion; 0.49-0.55) (F7V) = 0.527 (+-0.002 sem, +-0.025 stdev); HIP d<75pc S/N>8 (N=184) (B-V)(F7V) = 0.514 ; prim. stan. iot Psc (but [Fe/H] ~ -0.3) (F7V) = 0.511 (+-0.003 sem, +-0.012 stdev); Gray01/03/06 (N=20) (B-V)(F7V) = 0.50 ; Fitzgerald70, Morgan71 (B-V)(F7V) = 0.50 ; KenyonHartmann95 (B-V)(F7V) = 0.497 ; sec. stan. tet Boo (B-V)(F7V) = 0.491 ; median SIMBAD F7V d<25pc (N=12) (B-V)(F7V) = 0.49 ; cand. stan. 70 Tau (F7V) = 0.48 ; MorganAbt73/TableIII => adopt (B-V)(F7V) = 0.51 *** [updated 8/31/2019] => adopt (U-B)(F7V) = -0.012 => adopt (V-I)(F7V) = 0.579 => adopt (V-R)(F7V) = 0.290 => adopt (R-I)(F7V) = 0.289 => adopt (V-J)(F7V) = 0.971 => adopt (V-H)(F7V) = 1.184 => adopt (V-Ks)(F7V) = 1.244 => adopt (H-Ks)(F7V) = 0.060 => adopt (J-H)(F7V) = 0.213 => adopt (K-W1)(F7V) = 0.027 => adopt (G-V)(F7V) = -0.100 => adopt (Bp-Rp)(F7V)= 0.671 => adopt (Bp-G)(F7V) = 0.264 => adopt (G-Rp)(F7V) = 0.408 (U-B)(F7V) = 0.00 ; Fitzgerald70 (U-B)(F7V) = 0.000 ; HIP d<75pc S/N>8 F7V N=99 (Mermilliod91 photometry) (F7V) = 0.579 (+-0.004 sem, +-0.022 stdev); Gray01/03/06 (N=20) (F7V) = 0.600 (+-0.001 sem, +-0.024 stdev); HIP d<75pc S/N>8 (N=192) Teff(F7V) = 6185 K ; sec. stan. iot Psc (median Teff, slightly metal poor) Teff(F7V) = 6207 K ; mean photometric Teff Teff(F7V) = 6208 K ; median Teff for Houk F7V stars with PASTEL Teffs (but Houk F7V~Gray F7.5V) Teff(F7V) = 6250 K ; GrayCorbally09 Teff(F7V) = 6253 K ; Boyajian12 Teff(F7V) = 6276 K ; median of 945 published Teffs for F7V stars Teff(F7V) = 6283 K ; Teff from smoothed SpT(Teff) trend Teff(F7V) = 6297 K ; pri. stan. tet Per (median Teff) Teff(F7V) = 6360 K ; GrayCorbally94 Teff(F7V) = 6394 +- 104 K ; vanBelle09 Teff(F7V) = 6417 K ; candidate stan. 70 Tau (median Teff, slightly metal rich) => adopt Teff(F7V) = 6250 K (logT = 3.796) [updated 8/31/2019] BCv(F7V) = 0.013 mag ; Balona94(Teff=6250K) BCv(F7V) = 0.011 mag ; Bertone04(Teff=6250K) BCv(F7V) = -0.019 mag ; Flower96(Teff=6250K) BCv(F7V) = -0.032 mag ; Masana06(Teff=6250K) BCv(F7V) = -0.037 mag ; Casagrande18(Teff=6250K,logg=4.5) BCv(F7V) = -0.038 mag ; Bessell98(ATLAS9,logg=4.5,Teff=6250K) BCv(F7V) = -0.045 mag ; EEM fit to Casagrande06/08/10(Teff=6240K) BCv(F7V) = -0.045 mag ; Code76(Teff=6250K) => adopt BCv(F7V) = -0.035 [last updated 8/31/2019; adjusted so that BCv(5772K)=-0.085] Mv(F7V) = 3.09 mag ; exemplar 70 Tau (Hyad) Mv(F7V) = 3.22 mag ; deprecated stan. HD 126660 = tet Boo Mv(F7V) = 3.30 mag ; Wegner07 Mv(F7V) = 3.43 mag ; sec. stan. iot Psc Mv(F7V) = 3.61 mag ; median SIMBAD F7V d<25pc (N=1 Mv(F7V) = 3.8 mag ; GrayCorbally09 Mv(F7V) = 3.84 mag ; d<60pc SIMBAD F7V (N=138) Mv(F7V) = 3.87 mag ; pri. stan. tet Per Mv(F7V) = 3.87 mag ; B-V=0.510 => Mv(Wright05) Mv(F7V) = 3.95 mag ; B-V=0.510 => EEM fit to SIMBAD dwarfs d<25pc Mv(F7V) = 4.02 mag ; deprecated stan. HD 170153 = chi Dra (metal poor) => adopt Mv(F7V) = 3.85 mag [updated 9/20/2019] logL(F7V) = 0.370 dex ; Mv=3.85, BCv=-0.035 => Mbol = 3.815 => adopt logL(F7V) = 0.370 dex [updated 9/20/2019] => adopt Mbol(F7V) = 3.815 mag [updated 9/20/2019] Rad(F7V) = 1.306 Rsun ; Teff=6250K, logL=0.370 => adopt Rad(F7V) = 1.306 Rsun [updated 9/26/2019] Mass(F7V) = 1.28 Msun ; EEM Teff vs. Mass fit for binaries (Teff=6240K) Mass(F7V) = 1.212 Msun ; Ekers15 ML calibration for logL=0.36 Mass(F7V) = 1.21 Msun ; EEM logL vs. Mass fit for binaries (logL=0.36) Mass(F7V) = 1.18 Msun ; EEM Mv vs. Mass fit for binaries (Mv=3.87) Mass(F7V) = 1.15 Msun ; sec. stan. tet Per (Ghezzi10) => adopt Mass(F7V) = 1.21 Msun # No standard Morgan65, MK73, MorganAbt73, Cowley74, MK78, Keenan85, Corbally86, Gray89, and GrayNstars do not list a F7V standard. MorganAbt73 lists F6V standard (B-V=0.46) and F8V standard (B-V=0.52), but no F7V standard. Skiff08 did not flag any stars as F7V MK standards. # Primary Standard HD 16895 = tet Per = 13 Per = HIP 12777 = HR 799 = GJ 107A *F7V: JM53,Cowley76,Gray01 F7.5V: Morgan38 F8V: Barry70(F8Vb),Abt81,Bidelman85(F8) F6V: Roman50 F5: Ljunggren61 No Houk type. Lit. types have ranged F6-F8, but the only decent F7V standard that is near the color-mag main sequence (tet Boo and iot Psc are >0.4 mag off). B-V(HIP)=0.514, Vmag=4.10, Mv=3.85, dMv=-0.05, par=89.0+-0.5 mas. Has M-type companion 13" away. Schiavon07 lists [Fe/H]=-0.02 dex, Teff=6118K, logg=4.35 dex. Takeda07 lists T=6350K, logg=4.32 dex, [Fe/H] = 0.06. The PASTEL catalog lists several Teff, logg, [Fe/H] estimates: = 6297K (+-36K sem, +-145K rms), = 4.35 (+-0.04 sem, +-0.19 rms), <[Fe/H]> = -0.006 (+-0.017 sem, +-0.071 rms). So the gravity is very dwarf-like and its metallicity is apparently very solar-ish. It's color is very representative of the median B-V for F7V stars. This might be the F7V standard with the best pedigree (given the problems with the other ones). Mv=3.87(HIP,HIP2). # Secondary Standards HD 222368 = iot Psc = 17 PSc = HIP 116771 *F7V: JM53,Jaschek64(majority),Jaschek78,Houk,Gray89,Gray01 F8V: Barry70(F8Va uv metals weak),Roman50,Kennedy83,Bidelman85(F8) Gray agreed twice with original JM53 classification. B-V(HIP)=0.507, Vmag=4.13, Mv=3.43, dMv=-0.42, par=72.5+-1.1 mas. PASTEL compilation has many estimates of Teff, logg, metallicity: = 6185 K (+-23 K sem, +-97 K rms), = = 4.13 (+-0.04 sem, +-0.20 rms), <[Fe/H]> = -0.17 (+-0.02 sem, +-0.11 rms). So star is slightly metal poor and slightly lower surface gravity than typical dwarfs. Mass = 1.15+-0.1 Msun (Ghezzi10). # Exemplar HD 27991 = 70 Tau (Hyades member) *F7V: Morgan65,Cowley76,Gray01 F8V: Treanor60 G0V: Harlan74 Hyades member, so slightly metal rich. Has benefit that Morgan classified amongst other F-type stars (many of which are now considered standards). But, it is a 0.1" separation visual binary with 13.15 year orbit, apparently nearly equal mass (K1=12.37 km/s, K2=13.63 km/s; Pourbaix00). B-V = 0.490 (Mermilliod91), U-B=0.012+-0.018(Mermilliod91), V = 6.462 (Mermilliod91). plx = 21.20+-0.92 mas (vanLeeuwen07). PASTEL catalog: = 6417 K (+-19 K sem, +-37 K rms), = 4.49 (+-0.01 sem, +- 0.01 rms), <[Fe/H]> = 0.07 (+-0.04 sem, +-0.05 rms). Metallicity estimates roughly consistent with Hyades metallicity [Fe/H] ~ +0.1. Mv = 3.09. # Deprecated Standards HD 126660 = tet Boo = HIP 70497 = HR 5404 = GJ 549A *F7V: JM53,Barry70(uv metals vweak),Cowley76(stan),Gray01 F7II-III: Bouw81 (unlikely given its Mv) F6IV: MK43 F6V: Bouigue59 F5: Bidelman85 No Houk type. B-V(HIP)=0.497, Vmag=4.04, Mv=3.22, dMv=-0.57, par=68.6+-0.6 mas Probably OK standard if JM53, Gray, & Barry all agree its F7V. Surprisingly lack of Teff estimates, except Taylor05 => Teff=6238. HD 170153 = chi Dra = 44 Dra = HIP 89937 = HR 6927 = GJ 713 F7V: JM53,Cowley76,Cowley67 *F7V metal-weak: Gray01 hF8gF6mF6: Jaschek89 F8Vb: Barry70 F6V: Roman50 ("lines strong"), MK43(!) This star appears to be inappropriate for use as a standard given the comments by Gray01, Jaschek89, and Roman50. B-V(HIP)=0.489, Vmag=3.55, Mv=4.02, dMv=0.28, par=124.1+-0.5 mas. HD 82543 = HR 3794 F6IV-V: Cowley76(stan) F7IV-V: MorganAbt72(stan) F8II: Cowley73 F8IV: Harlan74,Cowley79(F8IV:) F5: Cannon K0III+A/F: Houk99 Houk99 notes "HR 3794; VISUAL DOUBLE p=153°d=0.1arcsec MAGS 7.0, 7.0; vSINi<15" Is the Houk99 type a typo? Cowley went from F8II (1973) -> F6IV-V (1976; standard!) -> F8IV: (1979). Not a useful standard at this time. # Other Stars Morgan65 classified 3 F7V Hyads: HD 27808, 27991, 28394. Might be worth looking at these a bit closer, as one or more might make for a better F7V standard than the stars previously mentioned. HD 27808: F7V according to Morgan65, but Morgan made it a F8V standard in MK78, and F8V according to Gray89 and Gray01. B-V=0.520+-0.007 (Mermilliod91). So no good as a potential F7V standard. HD 27991 = 70 Tau: F7V according to Morgan65, Cowley76, and Gray01, but G0V according to Harlan74. B-V=0.490+-0.000 (Mermilliod91). 0.1" separation visual binary with 13.15 year orbit, apparently nearly equal mass (K1=12.37 km/s, K2=13.63 km/s; Pourbaix00) HD 28394: F7V according to Morgan65, but F8V according to Gray01, and F6V according to Abt04. B-V=0.501+-0.001 (Mermilliod91). Too much variation in published types to be worthy of being considered a standard. Of the three F7V Hyads from Morgan65, HD 27991 would seem to have the best agreement among classifiers as an F7V, but it is a tight binary. HD 27808 can't be a F7V standard as it is a well-used F8V standard.