uvbybeta: Derive dereddened colors, metallicity, and Teff from Stromgren colors

Description

Derive dereddened colors, metallicity, and Teff from Stromgren colors

Usage

uvbybeta(xby, xm1, xc1, xhbeta, xn, eby_in, name)

Arguments

xby

Stromgren b-y color, in real magnitudes, scalar or vector

xm1

Stromgren line-blanketing parameter, real, scalar or vector

xc1

Stromgren Balmer discontinuity parameter, real, scalar or vector

xhbeta

H-beta line strength index. See details for use.

Spectral class integer indicator (1-8), scalar or vector. See details for class assignments.

eby_in

E(b-y) color, in real magnitudes, scalar. If not supplied, then E(b-y) will be estimated from the Stromgren colors.

name

string giving name(s) of star(s), scalar or vector. Used only when writing to disk for identification purposes.

Value

name: string giving name(s) of star(s), scalar or vector.
group: derived n, approximate spectral class
by: Stromgren b-y color, in real magnitudes, scalar or vector
hbeta.status: Flag: 0 = H-beta value is input; 1 = H-beta value is estimated
by0: dereddened color index, E(b-y)_0
m0: dereddened magnitude, m_0
c0: dereddened Stromgren Balmer discontinuity parameter, c_0
eby: color excess, E(b-y)
mv: dereddened visual magnitude, M_V
radius: estimated stellar radius, in R_solar
delm0.status: Metallicity flag: 1 if n=1; 2 if n=3; otherwise 0
delm0: estimated metallicity index, m0_ZAMS - m_0
teff: estimated stellar effective temperature, T_eff
warn: warnings from code

Details

Method and code adapted from FORTRAN routine of same name published by T.T. Moon, Communications of University of London Observatory, No. 78 (1985).

Set input xhbeta to 0 if it is not known, and the function ubvybeta will estimate a value based on xby, xm1,and xc1. H-beta is not used for stars in group 8. The indicator n gives approximate spectral class assignments as follows:

	
  n=1 B0 - A0, classes III - V, 2.59 < Hbeta < 2.88,-0.20 <   c0  < 1.00 
  n=2 B0 - A0, class   Ia     , 2.52 < Hbeta < 2.59,-0.15 <   c0  < 0.40 
  n=3 B0 - A0, class   Ib     , 2.56 < Hbeta < 2.61,-0.10 <   c0  < 0.50 
  n=4 B0 - A0, class   II     , 2.58 < Hbeta < 2.63,-0.10 <   c0  < 0.10 
  n=5 A0 - A3, classes III - V, 2.87 < Hbeta < 2.93,-0.01 < (b-y)o< 0.06 
  n=6 A3 - F0, classes III - V, 2.72 < Hbeta < 2.88, 0.05 < (b-y)o< 0.22 
  n=7 F1 - G2, classes III - V, 2.60 < Hbeta < 2.72, 0.22 < (b-y)o< 0.39 
  n=8 G2 - M2, classes  IV - V, 0.20 < m0    < 0.76, 0.39 < (b-y)o< 1.00

Examples

Run this code

#  Suppose 5 stars have the following Stromgren parameters.
#  Determine their stellar parameters.  
#  Result: 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

by = c(-0.001 ,0.403, 0.244, 0.216, 0.394)
m1 = c(0.105, -0.074, -0.053, 0.167, 0.186)
c1 = c(0.647, 0.215, 0.051, 0.785, 0.362)
hbeta = c(2.75, 2.552, 2.568, 2.743, 0)
nn = c(1,2,3,7,8)   
          
out = uvbybeta(by, m1, c1, hbeta, nn)
c(out$by0, out$teff, out$mv, out$radius)