O7.5V There are no known O7.5V standards, including in Walborn90 HIP contains only one O7.5V star: HIP 30496 = HD 44811. B-V(O7.5V) = -0.321 ; exemplar HD 152590 B-V(O7.5V) = -0.317 ; U-B=-1.125 trend Q-method B-V(O7.5V) = -0.314 ; exemplar HD 53975 B-V(O7.5V) = -0.31 ; Fitzgerald70 B-V(O7.5V) = -0.291 ; EEM dereddened HD 44811 => adopt (B-V)(O7.5V) = -0.317 [updated 2/7/2020] U-B(O7.5V) = -1.16 ; Fitzgerald70 U-B(O7.5V) = -1.155 ; EEM dereddened HD 44811 U-B(O7.5V) = -1.143 ; exemplar HD 152590 U-B(O7.5V) = -1.125 ; interp O3-O9V U-B(O7.5V) = -1.116 ; exemplar HD 53975 => adopt (U-B)(O7.5V) = -1.125 [updated 2/7/2020] Teff(O7.5V) = 34419 K ; Martins05(theo. scale) Teff(O7.5V) = 34750 K ; Massey05(Milky Way) Teff(O7.5V) = 35874 K ; Martins05(obs. scale),GrayCorbally09 Teff(O7.5V) = 36100 K ; EEM trend for O dwarfs 1/2020 ** Teff(O7.5V) = 36728 K ; Simon-Diaz17 median for O7.5V (N=4) Teff(O7.5V) = 36947 K ; Simon-Diaz14 linear fit for O7.5V Teff(O7.5V) = 37230 K ; Holgado18 Teff(O7.5V) = 37500 K ; Crowther97/Fig.3 => adopt Teff(O7.5V) = 36100 K (logT = 4.558) [updated 1/20/2020] Mv(O7.5V) = -4.88 mag ; Russeil03 Mv(O7.5V) = -4.835 mag ; Wegner07 (halfway between O7V and O8V) Mv(O7.5V) = -4.8 mag ; GrayCorbally09 Mv(O7.5V) = -4.75 mag ; Bowen08 Mv(O7.5V) = -4.68 mag ; EEM trend for O7.5V Mv(O7.5V) = -4.6 mag ; halfway between O7V (-4.8) and O8V (-4.4) Mv(O7.5V) = -4.6 mag ; Conti71(V) Mv(O7.5V) = -4.56 mag ; Martins06/obs.scale Mv(O7.5V) = -4.55 mag ; Martins06/theor.scale Mv(O7.5V) = -4.55 mag ; Garmany92 (O7.5V,IV) Mv(O7.5V) = -4.48 mag ; Martins05 Mv(O7.5V) = -4.1 mag ; Conti71(ZAMS) => adopt Mv(O7.5V) = -4.65 mag [updated 2/8/2020] BCv(O7.5V) = -3.570 mag ; Flower96 calibration for (Teff=36100K) BCv(O7.5V) = -3.39 mag ; Martins05(obs.scale) BCv(O7.5V) = -3.346 mag ; Bessell98 calibration for (Teff=36100K) BCv(O7.5V) = -3.334 mag ; LanzHubeny03/07 calibration (Teff=36100K) BCv(O7.5V) = -3.325 mag ; EEM interp O7V(-3.41),O8V(-3.24) BCv(O7.5V) = -3.32 mag ; Martins06(obs.scale) BCv(O7.5V) = -3.275 mag ; Balona94 calibration (Teff=36100K) BCv(O7.5V) = -3.27 mag ; Martins05(obs.scale) BCv(O7.5V) = -3.20 mag ; Martins06(theor.scale) => adopt BCv(O7.5V) = -3.33 [updated 1/31/2020] logL(O7.5V) = 5.088 dex ; Mv=-4.65, BCv=-3.33 => Mbol = -7.980 logL(O7.5V) = 5.05 dex ; Martins05(obs. scale) logL(O7.5V) = 5.040 dex ; EEM O dwarf trend for O7.5V logL(O7.5V) = 5.00 dex ; Martins05(theo. scale) => adopt logL(O7.5V) = 5.088 dex [updated 2/8/2020] => adopt Mbol(O7.5V) = -7.980 mag [updated 2/8/2020] logg(O7.5V) = 3.84 dex ; Holgado18 => adopt logg(O7.5V) = 3.84 dex [updated 1/31/2020] Rad(O7.5V) = 8.9462 Rsun ; Teff=36100K, logL=5.088 Rad(O7.5V) = 8.639 Rsun ; Martins05 (Teff=35876K,logL=5.047) => adopt Rad(O7.5V) = 8.946 Rsun [updated 2/8/2020] Mass(O7.5V) = 25+7-5 Msun ; Weidner10 Mass(O7.5V) = 26.06 Msun ; MIST/Choi16 solar tracks for logT=4.558,logL=5.088 => adopt Mass(O7.5V) = 26 Msun [updated 4/16/2022] # No Standards MK73, MK78, Walborn90, Garrison94 do not list O7.5V standards. # Exemplars HD 152590 O7V: Garrison77,Schild69(O7) *O7.5Vz: Sota14 O7.5V: Walborn72,Mathys88 O8: Houk78 V=8.454+-0.023, B-V=0.135+-0.014, U-B=-0.817+-0.011(Mermillio91) => Q-method(1/2020) => (B-V)o=-0.321, (U-B)o=-1.143, E(B-V)=0.456, Av=1.473. HD 53975 O7V: Bisiacchi76,Bisacchi82 O7.5V: Conti71,Walborn72 *O7.5Vz: Sota11 O8: Morgan55,Lesh68,Claria74 B7Iab/Ib: Houk88(apparently erroneous) V=6.473+-0.016, B-V=-0.099+-0.005, U-B=-0.963+-0.016(Mermilliod91) => Q-method(1/2020) => (B-V)o=-0.314, (U-B)o=-1.116, E(B-V)=0.215, Av=0.693. HD 53975 = BD-12_1788 O7.5V: Conti71,Walborn72 O8: Morgan55,Lesh68,Jaschek64(all) O7V: Bisiacchi76,Bisiacchi82 B7IAB/B: Houk88 B5p: Cannon # Other Stars Morgan55 classified three stars as O7.5V or variant: HD 44811 (O7.5V; V=8.4), HD 194334 (O7.5V; V=8.8) and HD 165921 (O7.5V:nn; V=7.3). Conti71 classified three stars as O7.5V or variant: HD 53975 (O7.5V; V=6.5), HD 46573 (O7.5Vf; V=8.0) and HD 171589 (O7.5Vf; V=8.3). Walborn72 classified two stars as O7.5V: HD 53975 and HD 152590. HD 152590 O7.5V: Walborn72 O7V: Garrison77 O7: Jaschek78(Schild69) O8: Houk78 B5: Cannon BD+60 513 HD 35619 HD 46573 HD 155806 *O7.5V((f))(e): Maiz-Apellaniz16 O7.5V((f))z(e): Sota14 O7.5IIIe: Conti73,Conti74,Negueruela04 O7.5Ve: Bisiacchi82 O7.5V[n]e: Walborn73 O7.5((f)): Mathys88 O8IIIe: Garrison77 O8Ve: Hiltner69 O8e: Weaver53 O9: Houk82 Emission lines. There are some other pre-1970 classifications. Good agreement on O7.5 subtype in recent decades. V=5.525+-0.008, B-V=0.005+-0.008, U-B=-0.965+-0.014(Mermilliod91). Q-method => (B-V)o=-0.336, (U-B)o=-1.202, E(B-V)=0.341, Av=1.097 (perhaps corrupted by the emission lines).