A9V

Garrison94 does not list an A9V anchor standard, and MK73 does not
list an A9V dagger standard. 

44 Cet (= HR 401 = HD 8511) is a A9V standard. Unfortunately 44 Cet is
significantly bluer than the d<75 pc A9V stars in the Hipparcos
catalog, perhaps due to a difference in standards between Houk and
Gray? Surprisingly none of the stars in the Gray03/Gray06 Nstars
surveys are classified as a pure A9V (although HD 20320 is classified
kA4hA9mA9V).

Based on the literature search reflected in this file, Pecaut12 adopts
HD 73450 as an A9V standard (good agreement among multiple
classifiers). 

GrayGarrison89:       HR 401 (=44 Cet)  - A9Vn (high-vsini standard) 
GrayNstars standards: HR 401 (=HD 8511) - A9V(n)
Pecaut12 standard:    HD 73450 (=BS Cnc) - A9V 

For A9V Hipparcos stars within 75pc, with parallax S/N > 8, and within
1 mag of the MS (N=13):

<V-I>(A9V)   = 0.353 (+-0.014 sem, +-0.044 stdev; N=13)
<V-J>(A9V)   = 0.623 (+-0.025 sem, +-0.091 stdev; N=13)
<V-H>(A9V)   = 0.740 (+-0.032 sem, +-0.106 stdev; N=13)
<V-Ks>(A9V)  = 0.800 (+-0.025 sem, +-0.112 stdev; N=13)
<J-H>(A9V)   = 0.118 (+-0.012 sem, +-0.030 stdev; N=13)
<H-K>(A9V)   = 0.059 (+-0.004 sem, +-0.015 stdev; N=13)
<Bt-Vt>(A9V) = 0.323 (+-0.010 sem, +-0.032 stdev; N=13)
<V-Vt>(A9V)  =-0.032 (+-0.002 sem, +-0.007 stdev; N=13)
<B-K>(A9V)   = 1.110 (+-0.037 sem, +-0.141 stdev; N=13)

(B-V)(A9V)   = 0.324 ; exemplar HD 6670 
(B-V)(A9V)   = 0.321 ; exemplar HD 50635 (Garrison89)
<B-V>(A9V)   = 0.306 (+-0.011 sem, +-0.035 stdev) ; HIP d<75pc S/N>8 (N=13)
(B-V)(A9V)   =  0.30  ; Fitzgerald70
(B-V)(A9V)   = 0.288 ; d<60pc SIMBAD A9V (N=8)
(B-V)(A9V)   =  0.275 ; Schmidt-Kaler82(halfway A8V-F0V)
(B-V)(A9V)   =  0.27  ; KenyonHartmann95
(B-V)(A9V)   = 0.268 ; smoothed trend SpT vs (B-V)o B9.5V-F3V 11/2021
(B-V)(A9V)   =  0.26  ; Morgan71
(B-V)(A9V)   = 0.255 ; A9V star HD 28910 (Garrison89)
(B-V)(A9V)   = 0.241 ; med B-V among Bidelman56 Praesepe A9Vs (minus E(B-V)=+0.01). 
(B-V)(A9V)   = 0.235 ; A9Vn weak standard HD 8511 (Garrison89)
(B-V)(A9V)   = 0.227 ; A9V+ star HD 70574 (Garrison89)
(B-V)(A9V)   = 0.214 ; A9V+ star HD 30780 (Garrison89)
=> adopt (B-V)(A9V)  = 0.27  *** [updated 9/20/2019]
=> adopt (U-B)(A9V)  = 0.069 
=> adopt (V-I)(A9V)  = 0.311
=> adopt (V-R)(A9V)  = 0.152
=> adopt (R-I)(A9V)  = 0.159 
=> adopt (V-J)(A9V)  = 0.545
=> adopt (V-H)(A9V)  = 0.630
=> adopt (V-Ks)(A9V) = 0.674
=> adopt (H-Ks)(A9V) = 0.044
=> adopt (J-H)(A9V)  = 0.086


(Ks-W1)(A9V) = 0.048 ; EEM trend for d<30pc for B-V=0.27
=> adopt (Ks-W1)(A9V) = 0.048 [updated 12/29/2019]

(G-V)(A9V) =  -0.087  ; HD 196385 PM* A9V
(G-V)(A9V) =  -0.078  ; HD 103928 PM* A9V
(G-V)(A9V) =  -0.075  ; HD 112934 PM* A9V
(G-V)(A9V) =  -0.072  ; HD 138936 PM* A9V
(G-V)(A9V) =  -0.065  ; HD 37594 * A9V
(G-V)(A9V) =   -0.064 ; V* DO Eri a2* A9VpSrEuCr
(G-V)(F0V) =  -0.06  ; adopted for F0V
(G-V)(A9V) =   -0.051 ; * 9 Lac PM* A9VkA7mA6
(G-V)(A9V) = -0.051  ; polynomial fit f(B-V)
(G-V)(A8V) =  -0.04  ; adopted for A8V
(G-V)(A9V) = -0.036 ; fit for A dwarfs from Kervella19 corrected for E(B-V), eval for (V-Ks)=0.674
=> adopt (G-V)(A9V) = -0.05 [updated 4/8/2022]

(Bp-Rp)(A9V) =  0.3194 ; 44_Cet
(Bp-Rp)(A9V) = 0.349   ; color trend for B-V=0.27
(Bp-Rp)(A9V) =  0.387  ; Evans18 trend for V-I=0.311
=> adopt (Bp-Rp)(A9V) = 0.349 [updated 11/18/2020]

(Bp-G)(A9V)  = 0.131   ; color trend for B-V=0.27
(Bp-G)(A9V)  =  0.1415 ; 44_Cet
=> adopt (Bp-G)(A9V) = 0.131 [updated 11/18/2020]
 
(G-Rp)(A9V) =  0.1780  ; 44_Cet
(G-Rp)(A9V) = 0.219    ; color trend for B-V=0.27
=> adopt (G-Rp)(A9V) = 0.219 [updated 11/18/2020]

(U-B)(A9V)   = 0.08  ; Fitzgerald70
(U-B)(A9V)   = 0.069 ; HIP d<75pc S/N>8 A9V N=11 (Mermilliod91 photometry)

(V-I)(A9V)   = 0.26  ; weak standard HD 8511
(V-Ks)(A9V)  = 0.596 ; weak standard HD 8511

(g-r)(A9V)   = 0.137 ; Jordi06 (V-R)=>(g-r) for V-R=0.152
(g-r)(A9V)   = 0.060 ; Covey07 interp A7V to F0V
(g-r)(A9V)   = 0.052 ; Bilir05 (B-V)=>(g-r) for B-V=0.27
=> adopt (g-r)(A9V) = 0.06 [updated 10/10/2020]

Teff(A9V) =   7020 K ; Boyajian12
Teff(A9V) =   7380 K ; GrayCorbally09
Teff(A9V) =   7390 K ; Schmidt-Kaler82(halfway A8V-F0V)
Teff(A9V) = 7396 K ; Zorec12 median 
Teff(A9V) = 7430 K ; mean photometric Teff
Teff(A9V) = 7451 K ; median of 90 published Teffs for A9V stars
Teff(A9V) = 7500 K ; median Teff for 3 A9V from Gray17
Teff(A9V) =   7540 K ; GrayCorbally94
Teff(A9V) = 7606 K ; weak stan. HD 8511 median Teff (see below)
=> adopt Teff(A9V) = 7400 K (logT = 3.869) [updated 9/24/2020]
[EEM 9/24/2020: 7400K fits smoothly on B-V vs. Teff sequence, agrees with modern Zorec Teff estimates]

BCv(A9V) =  0.060 mag ; Balona94(Teff=7400K,BCv(5772K)=-0.085)
BCv(A9V) =  0.058 mag ; Bertone04(Teff=7440K,BCv(5772K)=-0.085)
BCv(A9V) =   0.035 mag ; Schmidt-Kaler82(halfway A8V-F0V + 0.13 mag)
BCv(A9V) =  0.031 mag ; Flower96(Teff=7400K,BCv(5772K)=-0.085)
BCv(A9V) =  0.020 mag ; EEM trend As/Fs
BCv(A9V) =  0.017 mag ; Masana06(Teff=7400K,BCv(5772K)=-0.085)
BCv(A9V) =  0.000 mag ; Bessell98(ATLAS9,logg=4.5,Teff=7440K,BCv(5772K)=-0.085
BCv(A9V) =  0.000 mag ; Code76(Teff=7400K,BCv(5772K)=-0.085)
BCv(A9V) = -0.005 mag ; Casagrande18(Teff=7400K,logg=4.5,BCv(5772K)=-0.085)
=> adopt BCv(A9V) = 0.02 [updated 9/24/2020, adjusted so that BCv(5772K)=-0.085]

logg(A9V) = 4.2 ; median logg for 3 A9V from Gray17

Mv(A9V) =  2.84 mag ; exemplar HD 6670
Mv(A9V) =  2.82 mag ; d<60pc A9V median N=8
Mv(A9V) =  2.73 mag ; d<60pc median N=8
Mv(A9V) =   2.55 mag ; Schmidt-Kaler82(halfway A8V-F0V)
Mv(A9V) =  2.51  mag ; median Mv for A9V calc using Kervella19 HIP & Gaia DR2 (d<100pc)
Mv(A9V) =   2.5  mag ; GrayCorbally09
Mv(A9V) =  2.45 mag ; A/F dwarf sequence for B-V=0.27
Mv(A9V) = 2.43 mag  ; linear B-V vs. Mv fit to d<50pc Gray01/03/06 dwarfs for B-V=0.27
Mv(A9V) =  2.42 mag ; interp BAF dwarf seq for B-V=0.27
Mv(A9V) =  2.38 mag ; Wright05(B-V=0.27)
Mv(A9V) =  2.18 mag ; d<60pc Mv(B-V=0.255)
Mv(A9V) =   2.07 mag ; Wegner07
Mv(A9V) =  2.07 mag ; sec. stan. HD 8511 = 44 Cet 
Mv(A9V) =  2.03 mag ; pri. stan. HD 73450 
=> adopt Mv(A9V)   = 2.43  mag [updated 9/26/2020]
=> adopt M_G(A9V)  = 2.37  mag [updated 12/10/2020] (Mv=2.43, G-V=-0.06)
=> adopt M_Ks(A9V) = 1.756 mag [updated 12/30/2020] (Mv=2.43, V-Ks=0.674)

logL(A9V) = 0.908 dex ; Mv=2.45, BCv=0.02 => Mbol = 2.47
logL(A9V) = 0.916 dex ; Mv=2.43, BCv=0.02 => Mbol = 2.45
logL(A9V) = 1.146 dex ; Zorec12 median
=> adopt logL(A9V) = 0.916 dex [updated 9/26/2020]
=> adopt Mbol(A9V) = 2.450 mag [updated 9/26/2020]

Mass(A9V) = 1.65 Msun ; HenryMcCarthy93 fit for Mv=2.4
Mass(A9V) = 1.65 Msun ; EEM Teff vs. Mass fit for binaries (Teff=7440K)
Mass(A9V) = 1.63 Msun ; EEM logL vs. Mass fit for binaries (logL=0.928)
Mass(A9V) = 1.63 Msun ; Ekers18 ML calibration for logL=0.928
Mass(A9V) = 1.62 Msun ; EEM Mv vs. Mass fit for binaries (Mv=2.4)
=> adopt Mass(A9V) = 1.63 Msun [updated 12/29/2019]

Rad(A9V) =  1.752 Rsun ; smoothed SpT vs Rad trend A/F dwarfs
Rad(A9V) = 1.7466 Rsun ; logL=0.916, Teff=7400K
Rad(A9V) = 1.7424 Rsun ; interp A7V-F2V for logT=3.869
Rad(A9V) =  1.731 Rsun ; logL=0.908, Teff=7400K
=> adopt Rad(A9V) = 1.747 Rsun [updated 9/26/2020]

# No standard

MK43, JM53, Morgan65, Cowley69, MK73, Cowley74, Houk75, Cowley76,
MK78, Keenan85, GrayNstars do not provide an A9V standard

Skiff08 did not flag any stars as A9V MK standards. 

Looked for stars with multiple A9V entries in Skiff07 MK catalog:
HD 73450 (3 refs; V=8.5; del Scu), many with two A9V refs.

# Primary Standard

HD 73450 = BS Cnc = BD+20_2144 = Cl* NGC 2632 RG 328 (Praesepe member)
 *A9V: Jaschek64(Bidelman56),Jaschek78(Bidelman56),Abt86,Gray02,Pecaut12(stan)
  A7V: Kennedy83(Rebeirot66)
  A0: Cannon

  At least agreement between Bidelman/Abt/Gray. This was the only
  "normal" A9V classified amongst 130 A-type stars in nearby open
  clusters in the survey of Gray & Corbally (2002).  Not in Hipparcos.
  Delta Scuti variable with amplitude 0.02 mag and period=0.05
  days. Member of NGC 2632 = M44 = Praesepe at d ~ 187 pc, with E(B-V)
  = 0.009 mag (WEBDA) => Av ~ 0.028. Neckel80 lists negligible
  extinction. Bidelman56 classified 5 Praesepe members as "A9" or
  "A9n", with median B-V=0.25 (but did not use A8 as a subtype). HD
  73450 has the median B-V of these five Bidelman56 A9
  stars. V=8.59(Tycho), B-V=0.208+-0.029(Tycho), B-V=0.25(Morel78),
  J=8.006+-0.019(2MASS), H=7.949+-0.027(2MASS),
  Ks=7.875+-0.026(2MASS), (V-Ks)=0.715(Tycho,2MASS).  Hence,
  correcting for 0.009 mag of E(B-V) reddening, the intrinsic (B-V)o
  for Praesepe A9 stars is 0.241. plx=4.9408+-0.2722mas(GaiaDR2).  Mv
  = 2.03.

# Secondary Standard

HD 8511 = 44 Cet = HR 401 (J0124-0800)
  A7Vn: Abt95
 *A9Vn: GrayGarrison89(stan)
  F0IVn(wk met): Paunzen01
  F0V: Cowley69,Grenier99

  GrayGarrison89 & GrayNstars A9Vn standard, but not considered A9V by
  anyone else (however part of the disagreement could be due to the
  changing late-A/early-F standards between the 50s/60s and
  post-MK78?).  plx=14.83+-0.77 mas(HIP), so probably unreddened.
  V=6.21(HIP), V=6.214+-0.003(Hauck97), B-V=0.235+-0.005(HIP,
  Mermilliod91), U-B=0.079+-0.010(Mermilliod91), V-I=0.26+-0.01(HIP),
  b-y=0.134+-0.004(Hauck97), J=5.791+-0.023(2MASS),
  H=5.65+-0.034(HIP), Ks=5.618+-0.008(2MASS),
  (V-Ks)=0.596(Mermilliod91, 2MASS), median of 4 published Teffs =
  7606 K => Teff=7762(Allende-Prieto99), Teff=7422+-187(Paunzen06),
  Teff=7680(Gerbaldi07#1), Teff=7532(Gerbaldi07#2). All the colors are
  bluer than the nearby (d<75pc) A9V stars in the Hipparcos catalog.
  Mv = 2.07.

# Exemplar

HD 6670 = 016.75451456974  -29.61514374503
   A6: Philip72
   A8V: Bond71
  *A9V: Houk82,Lu92,Chen03
   F0: Slettebak71,Drilling77

   V=9.38(HIP), B-V=0.338+-0.017(HIP), B-V=0.328+-0.009(Mermilliod91).
   plx = 4.9532+-0.0678 mas (GaiaDR2) => 202+-3 pc.  STILISM reddening
   map predicts E(B-V)=0.004+-0.014 => Av ~ 0.012 => E(B-V) = 0.328 -
   0.004 = 0.324.  Mv = 2.84.

# Other Stars

GrayGarrison89 did not classify any stars as A9V. 

Morgan65 classified one Hyad as A9V: HD 27459. 

Cowley76 did not have an A9V standard, but classified three bright
stars as A9V: HR 3284 (A9V:), HR 4916 (A9V), HR 820 (A9V).

Gray01/03/06 listed zero A9V stars in their nearby star survey. 

HD 4399 = SB 312 = [PS72] 253
   A6: Phillip72
  *A8V: Lu92,Chen03
   A9V: Bond71,Houk82,
   F0: Slettebak71

   Near south Galactic pole. V=9.68(Tycho), V=9.640(Mermilliod910,
   B-V=0.264+-0.037(Tycho), B-V=0.280(Mermilliod91),
   U-B=0.030(Mermilliod91). Av=0.03(Guarino92),
   E(B-V)=0.024(Bianchi11).

HD 27459 = HR 1356
   A7V: Adams35
   A8III: Gray01
   A9IV: Cowley74
   A9n: Wilson48
   A9V: Morgan65, Peniche81
   F0: 1920AN....211..289K
  *F0IV: GrayGarrison89,Abt95
   F0V: 1940ApJ....91..256T

   Only Hyad classified A9V by Morgan65. 

HD 6114 = HR 289
   A0: 1952IzKry...9...82G
   A3V: Adams35
  *A9V: Cowley74,Abt95
   A9IV: Abt81

HD 89455 = HR 4055
  *A9V: Malaroda95,Abt95

   Only two classifications are A9V.

HD 103928 = HR 4574
  *A9V: Cowley67,Cowley79
   F0V: Abt95

HD 184977 = HR 7453
   A9V: Cowley69,Abt95

HD 84812 = HR 3885
  *A9Vn: Cowley69,Abt95
   F0IVn: Cowley76
   F2: 1926MeUpp..11....1L