The Bappu photometric system
Bappu M.K.V., Chandra S., Sanwal N.B., Sinvhal S.D. 1962, MNRAS 123, 521
Photoelectric determinations of Hgamma absorption line intensity have been
made of stars in selected clusters and associations as well as in the general
galactic field. Interference filters having a width at half intensity of 45
Å were used to isolate spectral regions centred on 4280 Å, Hgamma
and 4410 Å.
The gamma indices derived, which represent a measure of the Hgamma absorption,
can be used in conjunction with unreddened values of either (U-B) or (B-V) for
spectral and luminosity class determinations of stars in the spectral range O6
to A0. The separation of age loci is shown to exist on gamma, (U-B)o diagrams
of clusters and associations having different ages. A gamma, Mv calibration
for the young, or less evolved stars, has been derived. Tests of such a
calibration have been made on the Orion association and NGC 2362. The distance
moduli thus obtained are in good agreement with the values derived from the
colour magnitude arrays.
Access to the data and references
Asiago Database on Photometric System (ADPS)
Indices and Parameters
Baird Atomic interference filters, at 4280 Å, Hgamma and 4410 Å
Half width 45 Å.
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Last update: 13 September 2002