The Beer photometric system

Basic Reference

Beer A. 1964, MNRAS 128, 261

Abstract

Analysis has been completed of 3360 photoelectric measurements of the Hgamma intensity in 461 stars of spectral types O and B, situated in the northern sky; 93 per cent of these are brighter than 7.5 mag. Three consistent series of measurements were obtained in the years 1960-1963, using the spectrometer at the f/18 coude focus of the 36-in reflector of the Cambridge Observatories. 154 of the stars were used as standards, adopting Petrie's system of absolute magnitudes. The photometric measuring-errors corresponded to absolute-magnitude errors of about +-0.2 for stars of a mean luminosity of -2.5 mag. There is, addition, the possibility of some physical intrinsic scatter in the relation between absolute magnitude and Hgamma strength, and that of errors in the assignment of standard absolute magnitudes. Some discussion has been made of emission-line stars, and particularly of the relation of these measurements to other absolute magnitude classification, of the use of eclipsing binaires in this work, and of the problem of calibration of the distance scale. Using interstellar absorption, estimated from colour excesses, new distances have been obtained for more than three hundred OB-stars. These have been mapped on the plane of the Milky Way, in order to make a comparison with the distribution of HI-region as revealed by 21-cm radio measurements, in continuation of the earlier work of 1961 concerned with southern B-stars. A star catalogue is given in Section 7.

Content

Access to the data and references

Asiago Database on Photometric System (ADPS)

Indices and Parameters

Rgamma

Rgamma = [(a) star / (a) lamp] / [(b) star / (b) lamp]

where (a) stands for the comparison region and (b) for Hgamma.

Filters

(a) Comparison regions
4255 - 4289 Å
4394 - 4427 Å
(b) Hgamma region
4325 - 4357 Å

Photomultiplier


Please, send your commentsto Jean-Claude.Mermilliod@obs.unige.ch
Jean-Claude.Mermilliod@obs.unige.ch
Last update: 13 September 2002