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UVBYBETA

UVBYBETA

Name


      UVBYBETA

Purpose


      Derive dereddened colors, metallicity, and Teff from Stromgren colors.

Explanation


      Adapted from FORTRAN routine of same name published by T.T. Moon,
      Communications of University of London Observatory, No. 78. Parameters
      can either be input interactively (with /PROMPT keyword) or supplied
      directly.

Calling Sequence


      uvbybeta, /PROMPT ;Prompt for all parameters
      uvbybeta,by,m1,c1,Hbeta,n ;Supply inputs, print outputs
      uvbybeta, by, m1, c1, Hbeta, n, Te, Mv, Eby, delm0, radius,
                      [ TEXTOUT=, Eby_in =, Name = ]

Inputs


      by - Stromgren b-y color, scalar or vector
      m1 - Stromgren line-blanketing parameter, scalar or vector
      c1 - Stromgren Balmer discontinuity parameter, scalar or vector
      Hbeta - H-beta line strength index. Set Hbeta to 0 if it is not
            known, and UVBYBETA will estimate a value based on by, m1,and c1.
            Hbeta is not used for stars in group 8.
      n - Integer (1-8), scalar or vector, giving approximate stellar
            classification
      (1) B0 - A0, classes III - V, 2.59 < Hbeta < 2.88,-0.20 < c0 < 1.00
      (2) B0 - A0, class Ia , 2.52 < Hbeta < 2.59,-0.15 < c0 < 0.40
      (3) B0 - A0, class Ib , 2.56 < Hbeta < 2.61,-0.10 < c0 < 0.50
      (4) B0 - A0, class II , 2.58 < Hbeta < 2.63,-0.10 < c0 < 0.10
      (5) A0 - A3, classes III - V, 2.87 < Hbeta < 2.93,-0.01 < (b-y)o< 0.06
      (6) A3 - F0, classes III - V, 2.72 < Hbeta < 2.88, 0.05 < (b-y)o< 0.22
      (7) F1 - G2, classes III - V, 2.60 < Hbeta < 2.72, 0.22 < (b-y)o< 0.39
      (8) G2 - M2, classes IV _ V, 0.20 < m0 < 0.76, 0.39 < (b-y)o< 1.00

Optional Input Keyword


      Eby_in - numeric scalar specifying E(b-y) color to use. If not
            supplied, then E(b-y) will be estimated from the Stromgren colors
      NAME - scalar or vector string giving name(s) of star(s). Used only
              when writing to disk for identification purposes.
      /PROMPT - if set, then uvbybeta.pro will prompt for Stromgren indicies
                interactively
      TEXTOUT - Used to determine output device. If not present, the
              value of the !TEXTOUT system variable is used (see TEXTOPEN)
              textout=1 Terminal with /MORE (if a tty)
              textout=2 Terminal without /MORE
              textout=3 uvbybeta.prt (output file)
              textout=4 Laser Printer
              textout=5 User must open file
              textout=7 Append to existing uvbybeta.prt file
              textout = filename (default extension of .prt)
      /PRINT - if set, then force display output information to the device
              specified by !TEXTOUT. By default, UVBYBETA does not display
              information if output variables are supplied (and TEXTOUT is
              not set).

Optional Outputs


      Te - approximate effective temperature
      MV - absolute visible magnitude
      Eby - Color excess E(b-y)
      delm0 - metallicity index, delta m0, (may not be calculable for early
              B stars).
      radius - Stellar radius (R/R(solar))

Example


      Suppose 5 stars have the following Stromgren parameters
      by = [-0.001 ,0.403, 0.244, 0.216, 0.394 ]
      m1 = [0.105, -0.074, -0.053, 0.167, 0.186 ]
      c1 = [0.647, 0.215, 0.051, 0.785, 0.362]
      hbeta = [2.75, 2.552, 2.568, 2.743, 0 ]
      nn = [1,2,3,7,8] ;Processing group number
      Determine stellar parameters and write to a file uvbybeta.prt
      IDL> uvbybeta, by,m1,c1,hbeta, nn, t=3
            ==> E(b-y) = 0.050 0.414 0.283 0.023 -0.025
                Teff = 13060 14030 18420 7250 5760
                M_V = -0.27 -6.91 -5.94 2.23 3.94
                radius= 2.71 73.51 39.84 2.02 1.53

System Variables


      The non-standard system variables !TEXTOUT and !TEXTUNIT will be
      automatically defined if they are not already present.
      DEFSYSV,'!TEXTOUT',1
      DEFSYSV,'!TEXTUNIT',0

Notes


      (1) **This procedure underwent a major revision in January 2002
      and the new calling sequence may not be compatible with the old** (NAME
      is now a keyword rather than a parameter.)
      (2) Napiwotzki et al. (1993, A&A, 268, 653) have written a FORTRAN
          program that updates some of the Moon (1985) calibrations. These
          updates are *not* included in this IDL procedure.

Procedures Used


      DEREDD, TEXTOPEN, TEXTCLOSE

Revision History


      W. Landsman IDL coding February, 1988
      Keyword textout added, J. Isensee, July, 1990
      Made some constants floating point. W. Landsman April, 1994
      Converted to IDL V5.0 W. Landsman September 1997
      Added Eby_in, /PROMPT keywords, make NAME a keyword and not a parameter
                W. Landsman January 2002



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