Intrinsic b-y, H-beta (for B stars), and V-I colors, and absolute magnitudes (plus appendix with J-K and V-K colors) version: 24 Mar 2002 Av = 4.2E(b-y); E(b-y) = 0.74E(B-V) Av = 3.1E(B-V); Ab = 4E(B-V) Av = 2.6E(V-I); E(V-I)/E(B-V) = 1.546 <---- main-sequence ----> <-- giants --> Ib (b-y)o beta V-I Mv (b-y)o V-I Mv (b-y)o Mv Spec O2 -5.6 -6.0 -7.0 O3 -5.6 -6.0 -7.0 O4 -5.4 -6.0 -6.5 O5 -5.2 -6.0 -6.5 O6 -5.2 -5.7 -6.5 O6.5 -5.1 O7 -4.9 -5.6 -6.5 O8 -4.6 -5.1 -6.5 O9 -0.13: -4.4 ^ -5.1 -6.1 O9.5 -4.0 | -5.1 -6.0 B0 -0.12 2.606 -3.8 | -5.0 -6.0 B0.5 2.604 | B1 -0.11 2.609 -0.24 -3.2 | -4.3 B2 -0.09 2.646 -2.5 same -3.7 B3 -0.08 2.681 -1.7 as for -3.0 B4 -0.073 dwarfs B5 -0.068 2.701 -0.16 -1.1 | -2.2 B6 -0.06 2.716 -0.9 | -1.9 B7 -0.051 2.723 -0.6 | -1.6 B8 -0.042 2.748 -0.07 -0.2 | -1.2 B9 -0.025 2.795 -0.04 +0.2 | -0.8 B9.5 2.827 -0.02 | A0 -0.005 2.861 0.00 0.6 | -0.6 0.032 -5.2 A1 +0.013 1.2 | -0.4 A2 0.031 1.4 v -0.2 0.051 -5.0 A3 0.054 1.7 0.054 0.0 0.074 -4.8 A5 0.072 2.1 0.072 0.3 0.062 -4.8 A7 0.114 2.4 0.102 0.5 0.107 -4.8 A9 0.172 2.5 0.150 0.6 F0 0.191 0.38 2.6 0.165 0.33 0.6 0.177 -4.7 F1 0.208 2.8 0.181 0.6 F2 0.225 3.0 0.197 0.6 0.203 -4.6 F5 0.285 0.52 3.4 0.260 0.7 0.271 F6 0.311 3.7 0.291 0.7 F7 0.323 3.8 0.307 0.6 0.348 F8 0.335 4.0 0.323 0.6 0.375 F9 0.356 4.2 0.6 G0 0.374 4.4 0.386 0.6 0.475 G1 0.382 G2 0.406 0.71 4.7 0.417 0.520 G3 0.416 G5 0.428 5.2 G7 0.57 -0.2 G8 0.444 5.6 0.58 0.92 -0.2 K0 0.472 0.87 5.9 0.60 1.05 -0.2 K1 0.492 6.1 K2 0.514 1.0 6.3 0.75 1.2 -0.3 K3 0.80 K4 0.85 -0.45 K5 0.656 1.2 8.0 0.90 1.4 K7 0.791 8.5 M0 1.5 9.2 1.00 1.6 -0.5 M1 1.88 M2 1.8 10.1 1.05 2.05 -0.6 M3 1.10 2.26 M4 11.3 1.15 2.55 -0.7 M5 2.7 12.3 1.20 2.87 -0.7 M6 1.35 3.30 -0.3 M7 1.9 3.78 +0.6 M8 4.34 +1.6 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Appendices I. Q versus spectral type for early-type stars Q = (U-B) - 0.72(B-V) [Johnson & Morgan 1953] = (U-B) - 0.645(B-V) for B1V-A1V [Heintze 1973, IAU Symp 54] type Q(JM) Q(H) O5 -0.93 -0.93 O6 -0.93 -0.93 O8 -0.93 -0.93 O9 -0.90 -0.89 B0 -0.90 -0.85 B0.5 -0.85 -0.81 B1 -0.78 -0.78 B2 -0.70 -0.70 B3 -0.57 -0.62 B4 -0.55 B5 -0.44 -0.47 B6 -0.37 -0.39 B7 -0.32 -0.32 B8 -0.27 -0.24 B9 -0.13 -0.16 B9.5 -0.12 A0 0.00 ------------------------------------------------------------------------------- II. Intrinsic colors for early-type Ia supergiants source: 1988ApJ...335..703F MK (b-y)o (B-V)o (U-B)o B0Ia -0.075 -0.22 -1.03 B0.5Ia -0.065 -0.19 -0.99 B1Ia -0.050 -0.17 -0.96 B2Ia -0.040 -0.15 -0.91 B2.5Ia -0.025 -0.14 -0.84 B3Ia -0.015 -0.12 -0.79 B5Ia 0.000 -0.09 -0.72 B8Ia 0.040 -0.01 -0.58 ------------------------------------------------------------------------------- III. V-I for late-type long-period variables For late-M type LPVs, the first volume of the H/T printed documentation offers the following V-I colors derived empirically. For types < M5, their colors match the The' et al. colors within errors. MK V-I err M5 3.3 0.8 M5.5 3.6 0.8 M6 4.0 0.8 M6.5 4.3 0.8 M7 4.7 0.8 M7.5 5.0 0.8 M8 5.4 0.8 M8.5 5.8 0.8 M9 6.1 0.8 M10 6.8 1.2 ------------------------------------------------------------------------------- IV. Intrinsic J-K and V-K colors Typical values found from MK standards and Johnson+2MASS data. MK J-K V-K B0V -0.17 -0.97 B2V -0.22 -0.89 B5V -0.20 -0.71 A0V -0.01 -0.17 F0V 0.15 0.52 G2V 0.29 1.26 K0V 0.40 1.74 M0V 0.80 3.29 G8III 0.66 1.77 K0III 0.76 1.94 K5III 0.95 3.14 M2III 1.04 3.89 M5III 1.17 4.73 M6III 1.26 M5e 1.38 M6e 1.2 M2Ib 1.22 M5Ib 1.25 carbon stars V460 Cyg 1.57 U Hya 1.57 Y CVn 1.72 T Lyr 2.31 ------------------------------------------------------------------------------- V. Solar colors from averages for MK standards between G1V and G3V B-V b-y U-B V-R R-I V-I MK stds 0.647 0.407 0.16 0.362 0.341 0.704 =============================================================================== sources: Mv for B0 and earlier from Phil Massey's 8th Canary Islands Winter School lectures, "Observations of the most luminous stars in Local Group galaxies". ??? Mv for later types from Keenan map in "MK Process". for giants G7 and later: Keenan & Barnbaum 1999 ApJ 518,859 b-y --- up to G0 from Garrison and Gray series, last is 2001 AJ 121,2148 --- later dwarfs from averages of MK standards with Crawford and/or Olsen photometry. --- later-type giants, from Ardeberg & Lindgren V-I --- for most stars from rough averages using E-region and Landolt standards --- M giants from The' et al PASP 102,565 --- G2V from average for many MK standards G1V to G3V. see also Table 4 of Bessell 1990PASP..102.1181B for computed colors from model spectra. discussion of O2 and O3 stars by Walborn et al. 2002 May AJ.