B1.5V Garrison94 does not list a B1.5V anchor standard, and MK73 does not list a B1.5V dagger standard. There is little agreement on which stars to use for B1.5V standards. None of the proposed standards originally were classified B1.5V before being considered standards. It appears that the standards themselves are a bit hotter and bluer than the mean colors for the majority of B1.5V in the literature. Garrison67 standard: Cl* NGC 2244 JOHN 10 - B1.5V [from Morgan65] Lesh68 standard: HD 215191 - B1.5V Walborn71 standard: HD 154445 - B1.5V Walborn90 standard: HD 36959 - B1.5V Tough to say what might be the best standard - none have long pedigree as B1.5V standard. HD 154445 may be best as its on the Walborn system, and it appears to be single. All Q-method calculations in this file have been updated with the most recent calibration (10/9/2011). B-V(B1.5V) = -0.265 ; EEM dereddened pri. stan. HD 154445 (via Q method) B-V(B1.5V) = -0.261 ; EEM dereddened sec. stan. HD 36959 (via Q method) B-V(B1.5V) = -0.252 ; calculated Q-method using U-B=-0.91 B-V(B1.5V) = -0.25 ; Fitzgerald70, Morgan71(halfway_B1-B2), JohnsonBorgman63 B-V(B1.5V) = -0.240 ; EEM dereddened N=9 HIP B1.5V stars (Q method,E(B-V)<0.1) => adopt (B-V)(B1.5V) = -0.252 [updated 9/26/2019] U-B(B1.5V) = -0.954 ; EEM dereddened pri. stan. HD 154445 (via Q-method) U-B(B1.5V) = -0.941 ; EEM dereddened sec. stan. HD 36959 (via Q-method) U-B(B1.5V) = -0.91 ; Bessell98, JohnsonBorgman63 U-B(B1.5V) = -0.872 ; EEM dereddened 17 HIP B1.5V stars (via Q-method) U-B(B1.5V) = -0.895 ; Johnson63 (interp. between B1V-B2V) U-B(B1.5V) = -0.88 ; Fitzgerald70 => adopt (U-B)(B1.5V) = -0.91 *** [updated 2/7/2020] => adopt Q(B1.5V) = -0.728 (=(U-B)-0.72*(B-V)) [updated 2/7/2020] => adopt (V-I)(B1.5V) = -0.281 => adopt (V-R)(B1.5V) = -0.115 => adopt (R-I)(B1.5V) = -0.168 => adopt (V-J)(B1.5V) = -0.572 => adopt (V-H)(B1.5V) = -0.703 => adopt (V-Ks)(B1.5V) = -0.752 => adopt (H-Ks)(B1.5V) = -0.047 => adopt (J-H)(B1.5V) = -0.132 (Bp-Rp)(B1.5V) = -0.390 ; Evans18 trend for V-I=-0.281 (g-r)(B1.5V) = -0.483 ; Covey07 interp B1V -0.49 to B3V -0.46 (G-V)(B1.5V) = -0.021 ; fit for B dwarfs from Kervella19 corrected for E(B-V), eval for (V-Ks)=-0.752 => adopt (G-V)(B1.5V) = -0.021 [updated 4/8/2022] Teff(B1.5V) = 20184 K ; Simon-Diaz17 for B1.5V (N=8; gap between logT=4.34-4.37, 4.25-4.27) Teff(B1.5V) = 21584 K ; N=9 B1.5V from Brown94 Teff(B1.5V) = 21630 K ; EEM N=51 Teffs Teff(B1.5V) = 21787 K ; N=21 B1.5V from Philip80 (Jaschek78 SpTs) Teff(B1.5V) = 22948 K ; U-B=-0.91 => Teff(Bessell98) Teff(B1.5V) = 23000 K ; Bohm-Vitense81 Teff(B1.5V) = 23400 K ; Chavez95 (+700-400K) Teff(B1.5V) = 23516 K ; interp. B1V and B2V Teffs as f(B-V) for B-V=-0.25 Teff(B1.5V) = 24000 K ; non-standard HD 37744 (Nieva14) Teff(B1.5V) = 24400 K ; Bessell98 Teff(B1.5V) = 24575 K ; Q=-0.730 => Nieva13 calibration Teff(B1.5V) = 24627 K ; sec. stan. HD 36959 (median Teff) Teff(B1.5V) = 24845 K ; median for Braganca12 B1.5V stars (N=2) Teff(B1.5V) = 24918 K ; pri. stan. HD 154445 (median Teff) Teff(B1.5V) = 25000 K ; Crowther97/Fig.3 Teff(B1.5V) = 25087 K ; B-V=-0.25 => Teff(Napiwotzki93) Teff(B1.5V) = 25340 K ; Theodossiou90 Teff(B1.5V) = 25881 K ; B-V=-0.25 => Teff(Bessell98,logg=4.3) Teff(B1.5V) = 26100 K ; non-standard HD 36969 (Nieva14) => adopt Teff(B1.5V) = 24500 K (logT = 4.389) [updated 9/20/2019] BCv(B1.5V) = -2.408 ; Bertone04 (ATLAS, Teff=24500K, set so BCv(5772K)=-0.085) BCv(B1.5V) = -2.435 ; LanzHubeny03/07 (Teff=24500K, set so BCv(5772K)=-0.085) BCv(B1.5V) = -2.438 ; Nieva13(Teff=24500K, set so BCv(5772K)=-0.085) BCv(B1.5V) = -2.440 ; Balona94 (Teff=24500K, set so BCv(5772K)=-0.085) BCv(B1.5V) = -2.449 ; Bessell98 (Teff=24500K, set so BCv(5772K)=-0.085) BCv(B1.5V) = -2.455 ; Flower96 (Teff=24500K, set so BCv(5772K)=-0.085) BCv(B1.5V) = -2.464 ; Code76 (Teff=24500K, set so BCv(5772K)=-0.085) => adopt BCv(B1.5V) = -2.44 [updated 9/20/2019, set so BCv(5772K)=-0.085] Mv(B1.5V) = -3.42 mag ; pri. stan. HD 154445 (see below) Mv(B1.5V) = -2.89 mag ; Upper Sco main sequence (B-V=-0.25, rms +-0.39 mag) Mv(B1.5V) = -2.88 mag ; Wegner07 Mv(B1.5V) = -2.81 mag ; Russeil03 Mv(B1.5V) = -2.66 mag ; Bowen08 Mv(B1.5V) = -2.58 mag ; sec. stan. HD 36959 (see below, in ONC) Mv(B1.5V) = -2.50 mag ; ONC main sequence (B-V=-0.25, rms +-0.48 mag) => adopt Mv(B1.5V) = -2.60 mag [updated 9/20/2019] => adopt M_Ks(B1.5V) = -1.848 mag = Mv - (V-Ks) = -2.60 - 0.752 [updated 12/30/2020] logL(B1.5V) = 3.912 dex ; Mv = -2.6, BCv=-2.44 => Mbol = -5.04 logL(B1.5V) = 3.839 dex ; logL/Teff trend for OB dwarf EBs (Torres10; Teff=24500K) => adopt logL(B1.5V) = 3.912 dex [updated 9/26/2019] => adopt Mbol(B1.5V) = -5.040 mag [updated 9/26/2019] Mass(B1.5V) = 10.19 Msun ; EEM Teff vs. Mass fit for binaries (Teff=25000K) Mass(B1.5V) = 10.14 Msun ; Ekers15 ML calibration for logL=3.98 Mass(B1.5V) = 9.95 Msun ; MIST/Choi16 solar tracks logT=4.389,logL=3.912 Mass(B1.5V) = 9.85 Msun ; EEM logL vs. Mass fit for binaries (logL=3.89) Mass(B1.5V) = 9.73 Msun ; Harmanec88 Mass(B1.5V) = 9.59+-0.27 Msun ; Eclipsing binary V1034 Sco B (Torres10) Mass(B1.5V) = 9.53 Msun ; EEM Mv vs. Mass fit for binaries (Mv=-2.6) Mass(B1.5V) = 8.49 Msun ; Eclipsing binary mu01 Sco (vanAnterwerpen09) => adopt Mass(B1.5V) = 9.9 Msun [updated 4/16/2022] Rad(B1.5V) = 5.016 Rsun ; Teff=24500K, logl=3.912 => adopt Rad(B1.5V) = 5.016 Rsun [updated 9/26/2019] # No Standard Houk75 and Keenan85 do not list a B1.5V standard # Primary Standard HD 154445 = HR 6353 = HIP 83635 *B1.5V: Walborn71(stan),Walborn72 B1V: Morgan55,Feast57(B1V:),Jaschek64(all),Houk99(from SIMBAD) No new published classifications after Walborn72. No sign of binarity from Vizier search. V=5.620+-0.010 (Mermilliod91), Cousins71 lists B-V=0.155, U-B=-0.65 => updated Q-method calibration (10/9/2011) => (B-V)o = -0.265, E(B-V) = 0.420, (U-B)o = -0.954, Av=1.363. Plx = 2.92+-0.46 mas => D = 342+-55 pc => Mv = -3.42+-0.34 mag (but no statistical correction for poor parallax). Hauck97 photometry dereddened following Castelli91: (b-y)o=-0.132, c0=0.027, E(b-y)=0.314, Av=1.375 mag. Teffs: 24515K(U-Bo=>Bessell98), 24545K(EEM,Hauck97 phot. => Balona94 calibration), 24918K(EEM,Hauck97 beta phot.=>BalonaShobbrook84 calibration), 24945K(EEM,Hauck97 phot.=>Napiwotzki93 calibration), 25200K(Philip80) => median Teff = 24918K. # Secondary Standard HD 36959 = HR 1886 *B1.5V: Walborn90(stan) B1V: Sharpless52,Morgan55,Jaschek64(all),Lesh68,Houk99(Garrison type),Abt77 Jaschek64 lists a mix of B0 and B1 temp types. V=5.6 mag, but has V=8.8 mag companion 0.55" away. Bright B1V standard star HD 36960 is 36" away. Strangely *all* publshed types before Walborn90 considered the star B1V, but Walborn90 considered it a B1.5V standard. Johnson66 lists V=5.67. Cousins71 lists B-V = -0.220, U-B = -0.91 => Q = (U-B) - 0.72*(B-V) = -0.7516 => updated Q-method (10/9/2011) => (B-V)o = -0.261, E(B-V)=0.041, (U-B)o = -0.941, Av=0.133. Shull85 reports logN_HI = 20.40+-0.10, so using Savage & Mathis (1979) relation logN_HI/E(B-V) = 4.8e21 atoms/cm^2/mag, then E(B-V) = 0.052. Then (B-V)o = (B-V) - E(B-V) = -0.220 - 0.052 = -0.272, and (U-B)o = (U-B) - 0.72*E(B-V) = -0.91 - 0.72*0.052 = -0.947. vanLeeuwen07 plx = 1.21+-0.41 mas. In Orion Nebula Cluster, so adopt mean plx = 2.38+-0.03 mas (Menten+2007,Kraus+2007, Hirota+2007,Jeffries+2007) => Mv = -2.58+-0.03 mag. Hauck97 photometry dereddened following Castelli91: (b-y)o=-0.110, co=0.036, E(b-y)=0.018, Av=0.080 mag. Teffs: 23301K(EEM, Hauck97 phot. => Napiwotzki93 calibration), 24208K(U-Bo=>Bessell98), 24547K(Brown94; but Brown94 classifies it as B1V variable), 24620K(EEM, Hauck97 beta phot.=>BalonaShobbrook84 calibration), 24635K(EEM, Hauck97 phot.=>Balona94 calibration), 24890K(Cunha94), 25100K(Kaufer94), 25380K(Gies92) => median Teff = 24627K. # Deprecated Standard HD 215191 B1V: Blaauw53,Jaschek64(all) *B1.5V: Lesh68(stan),Levato76 B2IV: Zorec09 All classifications B1-B2 range. HD 259105 = Cl* NGC 2244 JOHN 10 = NGC 2244 128 = BD+05_1281 B1V: Johnson62,Massey95,Vrancken97 *B1.5V: Morgan65,Garrison67(stan),Perez87 B2V: Hoag59 Garrison67 adopted JOHN 10 as B1.5V standard from Morgan65's B0V-B2V main sequence stars for NGC 2244. All classifications in B1-B2 range, but not consistent enough to probably consider as a standard star. # Other Stars The brightest star classified by Morgan55 as B1.5V is HD 151890 (V=3.0). The brightest star classified by Hiltner69 as B1.5V is HR 4942 (V=4.3) and HR 5440 (B1.5Vn; V=2.3). There are no B1.5V stars in Garrison96's table "The Brightest Stars". # Notes (G-V) for B dwarfs (4/8/2022): Using Kervella19, I selected B dwarfs with Hipparcos and Gaia DR2 parallaxes >3 mas, G & K mag errors of <0.03 mag, and E(B-V) <= 0.05, and corrected their VGKs photometry using the Kervella19 E(B-V) values (from STILISM) - corrected as Av=3.1*E(B-V), A_G = 0.9536*Av (LuhmanEsplin20 for low Av), A_Ks=0.382*E(B-V). For 627 B dwarfs with -0.79 < (V-Ks) < 0.10, I fit: (G-V) = 1.5662975867923815e-002 - 4.5474915703530211e-002*(V-Ks) - 2.0632426850689073e-001*(V-Ks)^2 - 1.0690949761461190e-001*(V-Ks)^3 (rms = 0.0148 mag). This fit should be OK between B1.5V and B9.5V types.