A7IV

MK73 dagger standard:    iot UMa (=HR 3569) - A7IV
Morgan71 standard:       iot UMa (=HR 3569) - A7IV
MorganAbt72 standard:    iot UMa (=HR 3569) - A7IV
Cowley74 standard:       iot UMa (=HR 3569) - A7IV
GarrisonGray89 standard: HR 3270 - A7IV [low-vsini stan.]
			 iot UMa - A7IVn [high vsini stan.]

The only two A7IV standards proposed appear to have HRD positions
consistent with other dwarfs (both HR 3270 and iot UMa). Suggests that
among late As, the spectral differences between dwarfs and subgiants
are subtle and may not necessarily signify differences in luminosity.

(B-V)(A7IV) = 0.237  ; (B-V)(A7V)=0.21 plus trend seen for other IV stars
(B-V)(A7IV) = 0.233  ; exemplar kap Boo = HD 124675 
(B-V)(A7IV) = 0.222  ; pri. stan. HD 70060 = HR 3270
(B-V)(A7IV) = 0.223(+-0.017 sem,+-0.036 stdev) ; SIMBAD median A7IV d<75pc,V<6.5(N=7)
(B-V)(A7IV) = 0.223  ; deprecated stan. HD 76644 = iot UMa 
(B-V)(A7IV) = 0.191  ; exemplar gam Boo = HD 127762 
=> adopt (B-V)(A7IV) = 0.22 [updated 2/2/2022]

Mv(A7IV) = 2.40 ; exemplar iot Boo = HR 5350 = HD 125161 (~main sequence)
Mv(A7IV) = 2.31 ; exemplar HD 76644 = iot UMa (~main sequence) 
Mv(A7IV) = 2.16 ; pri. stan. HD 70060 = HR 3270 (~main sequence)
Mv(A7IV) = 1.79(+-0.26 sem,+-0.59 stdev) ; SIMBAD median A7IV d<75pc,V<6.5(N=7)
Mv(A7IV) =  1.5  ; GrayCorbally09
Mv(A7IV) = 1.05 ; exemplar kap Boo = HD 124675
Mv(A7IV) = 0.92 ; exemplar gam Boo = HD 127762 


# No standards

JM53 and Houk88 do not list a A7IV standard. 

# Primary Standard

HD 70060 = HR 3270 (J0818-3639, V=4.4)
 *A7IV: GrayGarrison89(low-vsini stan.)
  A7III: Jaschek64(most),deVaucouleurs57,
  A4(M)A5-A7: Houk82
  A5: Cannon
  A5/7: Loden69

  Houk82 notes "HR 3270; |V SIN|I=130; OR COULD BE A5/7 III"
  Plx=34.93+-0.18 (HIP2), Vmag=4.44, B-V=0.222. HIP2 =>
  Mv=2.16, and only 0.03 mag above main sequence!

# Deprecated Standard 

HD 76644 = iot UMa = 9 UMa = HR 3569 = HIP 44127
  A7V: JM53,Jaschek64(all),Cowley67,Cowley69(stan),Barry70,Gray03(A7Vn)
 *A7IV: MorganAbt72,MK73,Cowley74(stan),Garcia89,GrayGarrison89(high-vsini stan.)
  A6V: Palmer68
  A5: Cannon
  
  V=3.12(HIP), B-V=0.223+-0.003(HIP), V-Ic=0.25(HIP).
  plx=68.92+-0.16mas(HIP2) => Mv=2.31 => 0.18 mag below MS, so seems
  to be MS. Spectroscopic binary. Basically A7V until ~Morgan72, then
  A7IV since until Gray03.  M2V component "BC" only 3.7" away.

# Exemplars

gam Boo = HD 127762 = HR 5435 (J1432+3818; V=3.0)
    A7III: MK43,Cowley76(standard),Abt81
    A7IIIn: Palmer68
   *A7IV+(n): Gray01
    A7IV+: GrayGarrison89
    A7III-IV: Abt95
    A5V: Adams35,Bouw81

    Generally good agreement on "A7" temperature type due to use in
    MK43. However GrayGarrison89 and Gray01 consider the star to be
    "IV+" luminosity class. I've decided to list this star as a
    candidate "A7IV+" standard. (B-V)=0.191+-0.006(HIP). V=3.04(HIP).
    plx=37.58+-0.14mas(HIP2) => Mv=0.92 => 1.07 mag above MS.

kap Boo = HD 124675 = HIP 69483
   A6V+: GrayGarrison89
  *A7IV: Slettebak55,Slettebak63,1962AnAp...25....1B,Palmer68,Gray01
   A7V: Adams35,Abt81,Abt95
   A8IV: Barry70(uv metals weak),Morgan72
   A8V: Levato78
   A9IV: 1958JO.....41..105B,Cowley69
   F0V: Roman49
   
   A of bright 14" cpm pair (STF 1821), with companion B (HIP 69481)
   of type F2V(Gray01) and Vmag=6.62. V=4.53(HIP),
   B-V=0.233+-0.012(HIP),
   V-I=0.23+-0.03(HIP). plx=20.1530+-0.0943mas(GaiaEDR3) => Mv=1.05 =>
   1.13 mag above MS.

iot Boo = HR 5350 = HD 125161 = HIP 69713
   A6V: Abt95
   A7V: Slettebak55
  *A7IV: Abt81,GrayGarrison89,Gray01(A7IV-)
   A8V: Barry70
   A9V: Cowley69

   37" binary. V=4.75(HIP), B-V=0.236+-0.015(HIP), V-I=0.19+-0.03(HIP).
   plx=33.8856+-0.082mas(GaiaEDR3) => Mv=2.40 => 0.20 mag below MS. 


# Other Stars

JM53 lists Altair (alf Aql) and alf Cep as non-standard A7IV/V stars.

Morgan65 classified only one Hyad as a subgiant: HD 28319 (=
BD+15_632) as a A7IVn.  But it is called A7III by MK78 and all
subsequent literature (GrayGarrison89, Gray89, Gray01).


HD 17093 = HR 812 = HIP 12832
   A7III: Abt95
   A7III-IV: Cowley69
  *A7IV: 1951ApJ...113..304B,GrayGarrison89