K9V

JM53, Houk75, KeenanMcNeil76, Keenan85, Keenan85, Kirkpatrick91,
Henry02 do not list any K9V standards.  Skiff08 does not flag any
stars as K9V MK standards.

Pecaut13 standard:     HIP 3261 [K9V following Gray06]

Keenan84 does not list K9 as a full subtype like K5 and M0, and "other
possible subdivisions are utilized only for interpolation whenever we
think that we can classify accurately enough to justify their
use. Thus when we call a star G3 we mean only that it is closer to G2
than to G5."

Gray01/03/06 classify 13 stars are K9V, and 11 have useful BVI colors
in HIP. The brightest are HIP 8768 (V=8.89) and HIP 63833
(V=9.05). Median HIP colors:

<B-V>(K9V) = 1.418 (+-0.016 sem, +-0.040 stdev; N=11)
<V-I>(K9V) = 1.735 (+-0.039 sem, +-0.103 stdev; N=11)
<B-I>(K9V) = 3.156 (+-0.057 sem, +-0.144 stdev; N=11)
The K9V star with median B-I color is HIP 3261 (V=10.58)

<B-V>(K9V) =  1.37  ; Fitzgerald70
(B-V)(K9V) =  1.38  ; 1 ARICNS K8V star
(B-V)(K9V) =  1.40  ; interpolated between K7V (1.34) and M0V (1.43)
<B-V>(K9V) = 1.418 ; 11 Gray03/06 K9V stars (+-0.016 sem, +-0.040 stdev)
(B-V)(K9V) =  1.44  ; B-V for Gray03/06 star with median B-I: GJ 1016 
=> adopt (B-V)(K9V)  = 1.42  ***
=> adopt (U-B)(K9V)  = 1.197 
=> adopt (V-I)(K9V)  = 1.808
=> adopt (V-R)(K9V)  = 0.902
=> adopt (R-I)(K9V)  = 0.906
=> adopt (V-J)(K9V)  = 2.915
=> adopt (V-H)(K9V)  = 3.539
=> adopt (V-Ks)(K9V) = 3.737 
=> adopt (H-Ks)(K9V) = 0.198
=> adopt (J-H)(K9V)  = 0.624
=> adopt (K-W1)(K9V) = 0.082

(G-V)(K9V) = -0.688 ; from color locus fit for B-V = 1.42
(G-V)(K9V) = -0.69  ; GJ_1016
=> adopt (G-V)(K9V) = -0.69 [updated 12/10/2018]


Teff(K9V) = 3724 K ; Casagrande08 Teff calibration for V-Ks=3.737
Teff(K9V) = 3808 K ; vanBelle09 Teff calibration for V-Ks=3.737
Teff(K9V) = 3816 K ; Mozurkewich03 for V-Ks=3.737
Teff(K9V) = 3856 K ; mean photometric Teff
Teff(K9V) = 3865 K ; Bessell95 for V-Ks=3.737
Teff(K9V) = 3883 K ; smooth Teff(SpT) trend
Teff(K9V) = 3884 K ; diBenedetto98 Teff calibration for V-Ks=3.728
Teff(K9V) = 3943 K ; Ramirez05 Teff calibration for B-V=1.42
Teff(K9V) = 3970 K ; GJ 1016 (Morales08)
Teff(K9V) = 4045 K ; Gray92 for B-V=1.42
Teff(K9V) = 4246 K ; Biazzo07 Teff calibration for B-V=1.42
=> adopt Teff(K9V) = 3880 K (logT = 3.589)

Mv(K9V)  =  8.78 mag ; Wegner07
Mv(K9V)  = 8.92 mag ; V-K=3.737 => EEM fit to MS data
Mv(K9V)  = 8.97 mag ; V-K=3.737 => EEM fit to Reid CNS3 data
Mv(K9V)  = 9.00 mag ; B-V=1.42 => Mv(Wright05)
Mv(K9V)  = 9.04 mag ; V-K=3.737 => Mv(JohnsonApps09)
Mv(K9V)  = 9.07 mag ; V-K=3.737 => Mv(EEM, fit to Winters15 data)
=> adopt Mv(K9V)   = 9.00 mag    [updated 4/27/2017]
=> adopt M_Ks(K9V) = 5.26 mag    [updated 4/27/2017]

BCv(K9V) =  -1.310 mag ; Flower96(Teff=3880K)
BCv(K9V) = -1.220 mag ; Mann15(V-J=2.907)
BCv(K9V) = -1.141 mag  ; interp K7V-M0V for V-K=3.737
BCv(K9V) =  -1.121 mag ; Bessell98(ATLAS9,logg=4.5,Teff=3880K)
BCv(K9V) =  -1.084 mag ; EEM fit to Casagrande06/08/10 (Teff=3880K)
=> adopt BCv(K9V) = -1.14 mag  [updated 3/8/2018]

BC_Ks(K9V) = 2.597 mag ; BCv=-1.14, V-Ks=3.737
BC_Ks(K9V) = 2.528 mag ; Mann15(V-J=2.907)
BC_Ks(K9V) = 2.517 mag ; BCv=-1.14, V-Ks=3.737
=> adopt BC_Ks(K9V) = 2.60 mag [updated 3/8/2018; BCv=-1.14, V-Ks=3.737]

logL(K9V) = -1.216 dex ; Mv=9.00, BCv=-1.22 => Mbol = 7.78
=> adopt logL(K9V) = -1.22 dex
=> adopt Mbol(K9V) =  7.78 mag

Mass(K9V) = 0.558 Msun ; Mann18 calib. for M_Ks=5.26
Mass(K9V) =  0.565 Msun ; EEM Teff vs. Mass fit for binaries (Teff=3880K)
Mass(K9V) =  0.567 Msun ; Eker15 calibration for logL=-1.22
Mass(K9V) =  0.58  Msun ; EEM logL vs. Mass fit for binaries (logL=-1.25)
Mass(K9V) =  0.611 Msun ; Benedict16 for M_Ks=5.26
Mass(K9V) =  0.660 Msun ; Torres10 for Mv=9.00
=> adopt Mass(K9V) = 0.558 Msun [updated 8/2/2018]

Rad(K9V) = 0.544 Rsun ; logL=-1.22,Teff=3880K
=> adopt Rad(K9V) = 0.54 Rsun

# Standard

GJ 1016 = HIP 3261 = CD-34_239 = LTT_377 = G269-17
  K9V: Gray06,Pecaut13
  K7V: Hawley97 (a rare K7?), Reid04

  There appear to be no K9V standard stars in the literature before
  2013.  PecautMamajek13 adopted HIP 3261 as their K9V standard based
  on Gray06's classification and an intermediate appearance of the red
  spectrum between that of GJ 673 (K7V) and GJ 701 (M0V) [HIP 111288
  was adopted as K8V standard; Gray06].  Gliese91 lists only "k"
  type. U-B=1.170 (M91), B-V = 1.440 (M91), plx = 51.2+-2.2 (HIP2),
  B-V=1.432 (HIP), V-I=1.75+-0.03 (HIP), Ks=6.884+-0.007 (2M)
  V=10.597+-0.05 (M91), (V-Ks) = 3.713 +- 0.05: Hamuy94
  spectrophotometric standard?  Teff(Morales+2008) = 3970K.