The Oja photometric system

Basic Reference

Häggkvist L., Lyngå G. 1970, Astron. Astrophys. Suppl. 1, 299

Abstract

This paper is part of an investigation of the distribution of stars in the direction perpendicular to the galactic plane. It is limited to the late-type stars, which are studied by means of interference filters; the break at the G band and the cyanogen absorption are measured. The catalogue includes, i.a., all late-type stars brighter than V = 5 north of declination -10d, and those brighter than V = 6 north of galactic latitude +60d.

The relation between the two-dimensional classification established for the G and K stars and the MK classification is studied. It is shown that the giants and the dwarfs are well separated from each other and that the separation can be made complete if the criteria are complemented by the B-V colour. It is also found that the M giants can be classified quite accurately by means of the same criteria.

The connection between the spectrophotometric criteria and the intrinsic colours in the UBV system is investigated, and it is found that different relations hold for the dwarfs and the giants. The mean errors of typical B-V colour excess derived from the criteria and B-V are about +- 0.02 for the dwarfs to +-0.05 for the giants.

The absolute magnitudes of the late-type giants are discussed and a relation between the mean absolute magnitude in a volume of space and the spectrophotometric criteria is derived from astrometric data only (trigonometric parallaxes and proper motions in combination with radial velocities), The dispersion of the absolute magnitude is +-0.6.

Content

Access to the data and references

Asiago Database on Photometric System (ADPS)

Indices and Parameters

m45, Ge, Ce

Ge = m(4269) - m(4508)
Ce = m(4176) - m(4269)

Filters

             Peak
 Filter   wavelength  Width
              [Å]      [Å]
     
  4508       4508       50
  4269       4269       43
  4176       4176       40

All interference filter from Baird Atomic.

Photomultiplier

EMI 9502B

Transformations

With Gyldenkerne system
g = 0.416 Ge + 0.105 Ce - 0.257
n = 0.241 Ge**2 -0.489 Ge +0.454 Ce +0.332
With the DDO system
C4245 = 0.085 Ge**2 + 0.846 Ge + 0.070 Ce - 0.329
C4142 = 0.831 Ce + 0.041

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Jean-Claude.Mermilliod@obs.unige.ch
Last update: 21 May 1996