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) = -0.31 ; Fitzgerald70 B-V(O7.5V) = -0.291 ; EEM dereddened HD 44811 U-B(O7.5V) = -1.16 ; Fitzgerald70 U-B(O7.5V) = -1.155 ; EEM dereddened HD 44811 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) = 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) = 36000 K (logT = 4.556) [updated 9/29/2019] 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) = -4.6 mag ; halfway between O7V (-4.8) and O8V (-4.4) Mv(O7.5V) = -4.55 mag ; Garmany92 (O7.5V,IV) Mv(O7.5V) = -4.48 mag ; Martins05 => adopt Mv(O7.5V) = -4.6 mag [updated 9/29/2019] BCv(O7.5V) = -3.561 mag ; Flower96 calibration for (Teff=36000K) BCv(O7.5V) = -3.39 mag ; Martins05(obs. scale) BCv(O7.5V) = -3.338 mag ; Bessell98 calibration for (Teff=36000K) BCv(O7.5V) = -3.27 mag ; Martins05(obs. scale) BCv(O7.5V) = -3.269 mag ; Balona94 calibration (Teff=36000K) BCv(O7.5V) = -3.226 mag ; LanzHubeny03/07 calibration (Teff=36000K) => adopt BCv(O7.5V) = -3.30 [updated 9/29/2019] logL(O7.5V) = 5.056 dex ; Mv=-4.6, BCv=-3.30 => Mbol = -7.900 logL(O7.5V) = 5.05 dex ; Martins05(obs. scale) logL(O7.5V) = 5.00 dex ; Martins05(theo. scale) => adopt logL(O7.5V) = 5.056 dex [updated 10/19/2019] => adopt Mbol(O7.5V) = -7.900 mag [updated 10/19/2019] Rad(O7.5V) = 8.671 Rsun ; Teff=36000K, logL=5.056 => adopt Rad(O7.5V) = 8.671 Rsun [updated 10/19/2019] # No Standards MK73, MK78, Walborn90, Garrison94 do not list O7.5V standards. # Candidate Standard? HD 53975 = BD-12_1788 O7.5V: Conti71,Walborn72 O8: Morgan55,Lesh68,Jaschek64(all) O7V: Bisiacchi76,Bisiacchi82 B7IAB/B: Houk88 B5p: Cannon Never mentioned as a standard. But at least agreement between Conti & Walborn. # Other Stars HD 152590 O7.5V: Walborn72 O7V: Garrison77 O7: Jaschek78(Schild69) O8: Houk78 B5: Cannon 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.