O9V

Garrison94 lists 10 Lac (=HD 214680 = HR 8622) as an O9V anchor standard,
and MK73 lists 10 Lac as the O9V anchor standard. 

MK43 standard:       10 Lac - O9V
     		     iot Ori - O9V (iot Ori is O9III in later literature!)
JM53 standards:      10 Lac, 14 Cep, HD 46202, HD 52266, HD 57682
Garrison67 standard: 10 Lac - O9V
Lesh68 standard:     10 Lac - O9V
Hiltner69 standard:  10 Lac - O9V 
Walborn71 standard:  10 Lac - O9V 
Houk75 standard      HD 52266 - O9V (primary standard) 
Garrison77 standard: 10 Lac - O9V
MK78 standard:       HD 46202 - O9V
Keenan85 standard:   HD 46202 - O9V
Walborn90 standards: HD 46202 & HD 93028 - O9V
GrayAtlas standard:  HD 46202 - O9V
GrayNStars standard: HD 46202 - O9V

Garcia89 lists 5 O9V MK standards:  HD 46202, 52266, 57682, 209481, 214680
(all of which are in JM53)

Skiff08 lists 2 O9V standards: HD 214680 = 10 Lac (MK73) & HD 46202 (MK73)

Updated all Q-method dereddenings in this file using updated
calibration (Oct 2011). Note from Mar 2021: If one extracts the stars classified as O9V and variants from SIMBAD, with parallax > 1 mas and default UBV photometry,
they follow the reddening vector: (U-B) = -0.8230 + 0.73631885*(B-V), although the bluest ones in SIMBAD are around (B-V)o=-0.25  (although
even these bluest ones are reddened)

B-V(O9V) = -0.318 ; EEM dereddened weak stan. 14 Cep (via Q-method)
B-V(O9V) =  -0.317 ; EEM dereddened pri. stan. 10 Lac (Lyman alpha =>E(B-V))
B-V(O9V) =   -0.314 ; EEM dereddened pri. stan. 10 Lac (via Q-method)
B-V(O9V) =    -0.314 ; EEM dereddened weak stan. HD 57682 (via Q-method)
B-V(O9V) = -0.312 ; from U-B=-1.11 from Q-method
B-V(O9V) =     -0.311 ; EEM dereddened 4 HIP O9V (Q-method, E(B-V) < 0.3)
B-V(O9V) =    -0.310 ; EEM dereddened weak stan. HD 52266 (via Q-method)
B-V(O9V) = -0.31 ; Morgan53,Johnson58,Johnson63,Johnson66,Fitzgerald70,Morgan71,Schmidt-Kaler82
B-V(O9V) =   -0.305 ; EEM dereddened sec. stan. HD 46202 (via Q-method)
B-V(O9V) =  -0.303 ; EEM dereddened sec. stan. HD 93028 (via Q-method)
B-V(O9V) = -0.27  ; Martins06
=> adopt (B-V)(O9V) = -0.312 [updated 2/7/2020]

The bluest B-V I can find for a O9V star is HIP 52849 (B-V = -0.227),
so <(B-V)o> must be bluer than this. 

U-B(O9V)  =  -1.076 ; EEM dereddened deprecated stan. HD 93028 (via Q-method)
U-B(O9V)  = -1.084 ; EEM dereddened sec. stan. HD 46202 (via Q-method)*
U-B(O9V)  =  -1.10 ; Martins06
U-B(O9V)  = -1.104 ; EEM dereddened N=4 O9V (via Q-method, E(B-V) < 0.3 mag)*
U-B(O9V)  =  -1.113 ; EEM dereddened deprecated stan. 14 Cep (via Q-method)
U-B(O9V)  =  -1.114 ; EEM dereddened deprecated stan. HD 57682 (via Q-method)
U-B(O9V)  = -1.119 ; EEM dereddened prim. stan. 10 Lac (via Q-method)*
U-B(O9V)  =  -1.12 ; Johnson58,Johnson63,Bessell98,Schmidt-Kaler82
U-B(O9V)  = -1.122 ; EEM dereddened prim. stan. 10 Lac (using Lyalpha)*
U-B(O9V)  =  -1.13 ; Fitzgerald70, Johnson66
=> adopt (U-B)(O9V) = -1.110 *** [updated 2/7/2020]
=> adopt Q(O9V)     = -0.886 [updated 2/7/2020]
=> adopt (V-K)(O9V) = -1.000 [updated 12/26/2020]
=> adopt (V-J)(O9V) = -0.764
=> adopt (V-H)(O9V) = -0.929
=> adopt (H-K)(O9V) = -0.071
=> adopt (J-H)(O9V) = -0.164
=> adopt (V-I)(O9V) = -0.369

(g-r)(O9V) = -0.62 ; Covey07

(Bp-Rp)(O9V) = -0.512 ; Evans18 trend for V-I=-0.369

Teff(O9V) =  31000 K ; non-stan. HD 326329 (Marcolino09)
Teff(O9V) = 31524 K ; Martins05(theo. scale),Martins06
Teff(O9V) = 31750 K ; Massey05(Milky Way)
Teff(O9V) =  31800 K ; Bessell98 
Teff(O9V) =  32000 K ; Crowther97/Fig.3 
Teff(O9V) = 32000 K ; HD 48099-2 (Martins11)
Teff(O9V) =  32000 K ; non-stan. HD 149757 (Repolust04)
Teff(O9V) = 32172 K ; EEM N=14 Teffs*
Teff(O9V) = 32882 K ; Martins05(obs. scale),GrayCorbally09
Teff(O9V) =  33000 K ; Schmidt-Kaler82
Teff(O9V) =  33200 K ; Bohm-Vitense81
Teff(O9V) = 33250 K ; pri. stan. HD 46202 (median Teff)*
Teff(O9V) = 33300 K ; EEM trend for all O stars 1/2020 **
Teff(O9V) =  33715 K ; U-B=-1.114 => Teff(Bessell98)
Teff(O9V) = 34100 K ; Nieva13 (N=1 star)
Teff(O9V) = 34108 K ; sec. stan. HD 57682 (median Teff)*
Teff(O9V) =  34550 K ; Theodossiou90 
Teff(O9V) = 34638 K ; Q=-0.885 => Nieva13 calibration
Teff(O9V) = 34678 K ; Simon-Diaz14 linear fit for O9V
Teff(O9V) = 34800 K ; Holgado18 
Teff(O9V) = 35355 K ; pri. stan. 10 Lac (median Teff)*
Teff(O9V) = 35481 K ; Simon-Diaz17 median for O9V (N=3)
=> adopt Teff(O9V) = 33300 K (logTeff = 4.522) [updated 1/20/2020]

Mv(O9V) = -4.62 mag ; Wegner07
Mv(O9V) = -4.5  mag ; Schmidt-Kaler82
Mv(O9V) = -4.48 mag ; sec. stan. HD 46202 (see below)
Mv(O9V) = -4.46 mag ; Russeil03
Mv(O9V) = -4.35 mag ; non-stan. HD 149757 (Repolust04)
Mv(O9V) = -4.3  mag ; GrayCorbally09
Mv(O9V) = -4.3  mag ; Conti71(V)
Mv(O9V) = -4.30 mag ; Bowen08
Mv(O9V) = -4.23 mag ; Garmany92 (O9V,IV)
Mv(O9V) = -4.21 mag ; EEM trend for O9V
Mv(O9V) = -4.12 mag ; Martins06/theor. scale
Mv(O9V) = -4.12 mag ; Martins06/obs. scale
Mv(O9V) = -4.10 mag ; pri. stan. 10 Lac (see below)
Mv(O9V) = -4.05 mag ; Martins05
Mv(O9V) = -4.038 mag ; logL/Teff trend for O dwarfs (Teff=33000K,logL=4.8234)
Mv(O9V) = -3.97 mag ; average (HD 46202, 10 Lac, HD48099-2, HD 93028)
Mv(O9V) = -3.89 mag ; HD 48099-2 (Mon OB2 member; Martins11)
Mv(O9V) = -3.7  mag ; Conti71(ZAMS)
Mv(O9V) = -3.6  mag ; 10 Lac (Walborn07)
Mv(O9V) = -3.41 mag ; sec. stan. HD 93028 (see below)
=> adopt Mv(O9V)   = -4.20 mag [updated 2/8/2020]
=> adopt M_Ks(O9V) = -3.20 mag = Mv - (V-Ks) = -4.2 - -1.0 [updated 12/30/2020]

BCv(O9V) =  -3.310 mag ; Flower96(Teff=33300K, set so BCv(Teff)=-0.085))
BCv(O9V) = -3.264 mag ; Chen19 PARSEC Teff=33300K,solar,logg=3.87
BCv(O9V) =  -3.20  mag ; Schmidt-Kaler82(BCv=-3.33 + 0.13 offset)
BCv(O9V) =  -3.169 mag ; Code76(Teff=33300K, set so Teff(5772K)=-0.085)
BCv(O9V) = -3.150 mag ; Nieva13(Teff=33300K)
BCv(O9V) = -3.14  mag ; Martins05(obs. scale)
BCv(O9V) = -3.129 mag ; Bessell98(ATLAS,logg=4.0,Teff=33300, set so Teff(5772K)=-0.085)
BCv(O9V) =  -3.116 mag ; Balona94(Teff=33300K, set so Teff(5772K)=-0.085)
BCv(O9V) = -3.106 mag ; LanzHubeny03(Teff=33300K,Z/Zsun=1)
BCv(O9V) = -3.06  mag ; Martins06(obs.scale)
BCv(O9V) = -3.01  mag ; Martins05(theor.scale)
BCv(O9V) = -2.93  mag ; Martins06(theor.scale)
=> adopt BCv(O9V) = -3.11 [updated 1/31/2020, BCv(5772K)=-0.085]

logL(O9V) = 4.50 dex ; sec. stan. HD 93028 (see below)
logL(O9V) = 4.60 dex ; HD 48099-2 (Martins11)
logL(O9V) = 4.72 dex ; Martins05(theo. scale)
logL(O9V) = 4.74 dex ; Marcolino09/HD326329 
logL(O9V) = 4.764 dex ; logL/Teff trend for O dwarfs (Teff=33000K)
logL(O9V) = 4.77 dex ; Martins05(obs. scale)
logL(O9V) = 4.77 dex ; pri. stan. 10 Lac (see below)
logL(O9V) = 4.820 dex ; Mv=-4.2, BCv=-3.11 => Mbol = -7.310
logL(O9V) = 4.87 dex ; non-stan. HD 149757 (Repolust04)
logL(O9V) = 4.92 dex ; sec. stan. HD 46202 (see below)
=> adopt logL(O9V) =  4.820 dex [updated 2/8/2020]
=> adopt Mbol(O9V) = -7.310 mag [updated 2/8/2020]

Mass(O9V) =  17.08 Msun ; Martins05/obs. Teff scale 
Mass(O9V) =  17.21+-0.46 Msun ; Eclipsing binary V1034 Sco A (Torres10)
Mass(O9V) =  17.78 Msun ; EEM Teff vs. Mass fit for binaries (Teff=32500K)
Mass(O9V) =  18.03 Msun ; Martins05/theo. Teff scale 
Mass(O9V) =  19+-5 Msun ; Weidner10
Mass(O9V) =  19.01+-0.44 Msun ; Eclipsing binary V3903 Sgr B (Torres10)
Mass(O9V) =  19.52 Msun ; EEM logL vs. Mass fit for binaries (logL=4.82)
Mass(O9V) =  19.60+-4.33 Msun ; Hohle10
Mass(O9V) =  19.69 Msun ; pri. stan. 10 Lac (Hohle10)
Mass(O9V) =  19.80 Msun ; Ekers18 ML calibration for logL=4.82
Mass(O9V) = 20.17 Msun ; MIST/Choi16 solar tracks for logT=4.522,logL=4.820
Mass(O9V) =   20.2  Msun ; non-stan. HD 149757 (Repolust04)
Mass(O9V) =  20.60 Msun ; EEM Mv vs. Mass fit for binaries (Mv=-4.2)
Mass(O9V) =  20.6+-1.7 Msun ; WR22B (Weidner10)
Mass(O9V) =  20.62 Msun ; Ekers15 ML calibration for logL=4.82
=> adopt Mass(O9V) = 20.2 Msun [updated 4/16/2022]

logg(O9V) = 3.65 dex ; non-stan. HD 149757 (Repolust04)
logg(O9V) = 3.87 dex ; Holgado18
logg(O9V) = 3.9 +- 0.1 dex ; Marcolino09/HD326329
logg(O9V) = 3.915+-0.15 (stdev) ; Martins05
=> adopt logg(O9V) = 3.87 dex [updated 1/31/2020]

Rad(O9V) = 6.7 +- 1.4 Rsun ; pri stan. 10 Lac (Gordon18)
Rad(O9V) = 7.471 Rsun ; Martins05 (Teff=32883K,logL=4.769)
Rad(O9V) = 7.7226 Rsun ; Teff=33300K, logL=4.820
Rad(O9V) = 8.9   Rsun ; HD149757/Repolust04
=> adopt Rad(O9V) = 7.723 Rsun [updated 2/8/2020]

# Primary Standard

10 Lac = HD 214680 = HR 8622 
  O9V: MK43,JM53,Garrison67(stan),Lesh68(stan),Hiltner69(stan),Walborn71(stan),MK73,Walborn73,Garrison77(stan),Garcia89

  Skiff07: 09V in 7 refs, plus a O8.5III (1936), O7.5V (1982), O8III
  (1971). Johnson (1963) lists the star as one of "The Ten Primary
  Standard Stars of the U, B, V System": V=4.88, B-V=-0.203,
  U-B=-1.04. Q = U-B - 0.72*B-V = -0.894. Mermilliod91:
  V=4.879+-0.014, B-V=-0.201+-0.008, U-B=-1.036+-0.010 => updated
  Q-method (1/2020) => (B-V)o=-0.315, (U-B)o=-1.119, E(B-V)= 0.112,
  Av=0.360.  logN_HI = 20.70+-0.13 (Bohlin78), 20.78+-0.10 (Shull85).
  If we adopt logN_HI = 20.74, then using Savage & Mathis 1979
  [N(HI+H2)/E(B-V) = 4.8e21], I estimate E(B-V) = 0.114. Then (B-V)o =
  (B-V) - E(B-V) = -0.203 - 0.114 = -0.317, and (U-B)o = (U-B) -
  0.72*E(B-V) = -1.04 - 0.72*0.114 = -1.122.  vanLeeuwen07 plx = 1.89
  +-0.22 mas => D = 529+-62 pc. Hence, Mv = -4.10+-0.25 mag, logL =
  4.77+-0.11 dex.  Teffs: 32380+-2220K(Zorec09),
  32845K(Adelman02,ubvy), 33000K(Kubiak73 in Adelman02),
  33690K(Daflon03), 33893K(U-Bo=>Bessell98), 34000K(Rauw12),
  35355K(Prugniel07#3), 35495K(Prugniel07#2), 35595K(Katz11),
  35900K(Snow94), 37500K(Prugniel07#1), 37500+-1000K(Herrero92),
  38000+-1000K(Schonberner88), 40000+-1300K(Gordon18) => <Teff> =
  35355K.  Mass = 19.69+-0.95 Msun(Hohle10).

HD 46202 = Cl* NGC 2244 JOHN 6 = ALS 8991 = MCW 438
 *O9V: JM53,MK78(stan),Keenan85,Garcia89,Walborn90(stan),GrayAtlas
  O9.5V: Martins11

  M91: V=8.186+-0.015, B-V=0.178+-0.011, U-B=-0.737+- => updated
  Q-method (1/2020) => (B-V)o=-0.305, (U-B)o=-1.084, E(B-V)= 0.483,
  Av=1.562. One of Walborn90's two O9V standards, and the O9V standard
  of MK78. Distance to NGC 2244 is 1660 pc (Dias+2001 catalog) => plx
  = 0.602 mas. Hence, Mv ~ -4.48, logL ~ 4.92.  Teffs:
  28952K(Corot12), 31309K(U-Bo=>Bessell98), 31500K(Daflon94),
  33000+-2000K(Mahy11), 33500K(Fitzpatrick07), 33500K(Martins11),
  34100+-600K(Briquet12), 35900K(Snow94) => median = 33250K.
  logg=3.92+-0.14(Fitzpatrick07). Mass = 23.0 Msun(Snow94).
  logL=4.85(Mahy11).

# Secondary Standard

HD 57682 = ALS 9302 = HR 2806 
 *O9V: JM53,Morgan55,Hiltner56,Lesh68,Buscombe69,Conti71,Conti73,Conti74,Bisiacchi76,Bisiacchi82,Garcia89
  O9IV: Walborn72
  B7Ib: Houk99

  Consistent classification as O9 subtype, and all as dwarf except
  Walborn72, and extreme outlier B7Ib by Houk. M91: V=6.418+-0.008,
  (B-V)=-0.189+-0.006, U-B=-1.026+-0.004 => updated Q-method (1/2020)
  => (B-V)o=-0.314, (U-B)o=-1.114, E(B-V)= 0.125, Av=0.401. Note that
  the Houk classification propagated to the XHIP and Wright03
  catalogs. I would think this would be of serious astrophysical
  consequence if the B7Ib classification was correct!  Teffs:
  31800K(Kilian94), 33000K(Rauw12), 33715K(U-Bo=>Bessell98),
  34500+-1000K(Martins11), 34500+-1000K(Grunhut09), ">35000K"(Buss95)
  => median Teff = 34108K. logg=3.85(Kilian94),
  logg=4.0+-0.2(Grunhut09),
  logg=4.00+-0.20(Martins11). [Fe/H]=0.01(Kilian94). logL=4.79+-0.25(Martins11).

# Deprecated Standards

HD 93028 = Cl Collinder 228 27 
  O9V: Jaschek78(Walborn72),Walborn73,Herbst76,Walborn90(stan)
 *O9IV: Sota14
  O9/B0V: Alexander16
  O8.5V: Levato81
  O8/9.5: Houk75
  O8.5III: Massey01
  O9I: Feast57,Beer61,Graham70
  O9III: Humphreys73

  While this is considered a O9V standard by Walborn90, there is
  surprising scatter in the luminosity class for this object. While
  none of the temperature types vary by more than +-0.5 from O9, there
  are multiple studies calling this object a supergiant or
  giant. Given the availability of higher pedigree O9V standards, I'm
  calling this a "weak standard". M91: V=8.366+-0.016,
  B-V=-0.069+-0.011, U-B=-0.936+-0.034 => revised Q-method (1/2020) =>
  (B-V)o=-0.312, (U-B)o=-1.110, E(B-V)= 0.243, Av=0.784.  One of
  Walborn90's O9V standards. Distance to Collinder 228 is 2201 pc
  (Dias+2001 catalog) => plx = 0.454 mas.  Star is surprisingly
  lightly reddened for such a large distance.  Hence, Mv ~ -3.41 mag,
  logL ~ 4.50 dex. Teffs: 33000K(Povich11),
  33500+-1000K(Fitzpatrick07), 35900K(Snow94) => median Teff = 33500K.
  logg=4.02+-0.15(Fitzpatrick07). Mass = 24.0 Msun(Snow94).
  logL=4.86(Povich11).

HD 52266 = ALS 9246 = MCW 494
  O9V: Houk,JM53,Morgan55,Hiltner56a,Hiltner56b,Garcia89
  O9IV(n): Walborn73
  O9.5V: Conti71,Conti73,Conti74
  O9.5III: Bisiacchi82
 *O9.5IIIn: Sota11
  B5Ia/b: Houk99

  Included in JM53 and Garcia89 compendia of standards, but the
  classification drifted after JM53. Weak pedigree for a standard
  star. This is another odd case (similar to HD 57682) where the Houk
  classification is for a mid-B supergiant, while all others consider
  it a late O. M91: V=7.205+-0.025, B-V=-0.035+-0.025,
  U-B=-0.905+-0.005 => updated Q-method (1/2020) => (B-V)o=-0.310,
  (U-B)o=-1.102, E(B-V)= 0.275, Av=0.887. Hiltner56a =
  1956ApJ...124..367H.  Hiltner56b = 1956ApJS....2..389H.  Teffs:
  32750+-1000K(Fitzpatrick07). logg=3.75+-0.25(Fitzpatrick07).  Mass =
  15.15 Msun(Hohle10).

HD 209481 = 14 Cep = HR 8406 = ALS 12096
  O9V: Jaschek78(JM53),Jaschek64(most),Lesh68(O9Vn),Garcia89,Walborn73(O9V:)
 *O9IV(n)+B1:V:: Sota11
  O8.5III+O9.5V: Conti71
  O6/7IV: Zorec09
  B0: Cannon

  Spectroscopic binary (O8.5III+O9.5V; 1971ApJ...170..325C). M91:
  V=5.561+-0.021, B-V=0.060+-0.011, U-B=-0.860+-0.007 => updated
  Q-method (10/8/2011) => (B-V)o=-0.318, (U-B)o=-1.130, E(B-V)= 0.378,
  Av=1.219.

# Other Stars

Walborn72 classifies three stars as O9V or variant: HD 93028 (O9V), HD
214680 (O9V) and HD 193322AB (O9V:((n))).

Lesh68 classifies four stars as O9V or variant: HD 193322, HD 209481,
HD 214680, HD 57682.