The distribution of optical spectral indices for QSO's fromU, B, V data
Abstract
A term is derived to correct the U, B, V measurements for the quasistellar objects for the presence of emission lines. The corrected colours for 102 objects are calculated using different values of emission line equivalent widths. From the corrected colours, the spectral indices for the optical continua are obtained, assuming that the continua may be represented by a powerlaw function F(v) v . The spectral indices so derived are compared with those calculated from scanner measurements, and the colour spectral indices that give the best agreement with the available scanner spectral indices are used to find the distribution of optical spectral indices for quasistellar objects. The mean spectral index for the sample is I 02 with standard deviation . No significant difference is found between the spectral indices of `radioquiet' objects and those that are strong emitters at radio frequencies.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 1972
 DOI:
 10.1093/mnras/160.4.407
 Bibcode:
 1972MNRAS.160..407E