uvbybeta {astrolibR}R Documentation

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.

xn

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.

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 

Value

A data frame with the following columns:

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

Author(s)

W. Landsman IDL coding 1988

R adaptation by Arnab Chakraborty June 2013

See Also

deredd

Examples

#  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)

[Package astrolibR version 0.1 Index]