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

In astrolibR: Astronomy Users Library

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)

Example output

 [1] -1.001000e+00 -5.970000e-01 -7.560000e-01 -7.840000e-01  3.940000e-01
 [6]  1.512000e+04  1.332600e+05 -4.200000e+04 -8.649000e+04  5.760000e+03
[11] -2.518191e-01 -6.704173e+00 -5.539919e+00  3.810778e+00  3.944941e+00
[16]  2.180991e-23  1.026017e-05  7.264477e-11  8.606610e-14  1.533924e+00

astrolibR documentation built on May 2, 2019, 3:26 a.m.