The 102, 65, 62 photometric system

Basic Reference

Eggen O.J. 1967, ApJ. Suppl. 14, 307


A total of 1300 observations in the UBV system have been obtained for 370 stars mostly later than K5, north of -10 deg. and brighter than 6.5 mag (visual). An additional 1000 observations of 260 of these stars were made using a 7102 photomultiplier and narrow-band filters centered near 6250, 6500 and 10200 A. Also, 100 UBV and 150 narrow-band observations were made of 41 fainter, known variables mostly of the semiregular and long-period types. The narrow-band magnitudes and colors are referred to as follows: (102), the magnitude at 10200A; (65, 62), the magnitude difference between the band passes at 6250A, which contains a strong TiO bandhead and 6500A which does not; and (102, 65), the magnitude difference between the 10200 and 6500 A band passes, both of which are relatively free of TiO and terrestrial water-vapor absorbtion.

The relation between the infrared luminosity, M(102), and the continuum color (102, 65) for values of (102, 65) redder than about - 1.6 mag (black-body Te = 6000 deg. K) is found to be the same for young disk (Hyades group) and old disk (Wolf 630 group, M67) giants. The reddest halo giants (M13, M5, M92) are at (102, 65) = -1.0 mag (black-body Te = 4200 deg.) and at a given temperature are about 2.5 mag brighter than the disk giants.

The TiO absorption in disk giants is the same as in the supergiants but less than half that in the main-sequence stars of the same temperature. The red instability region for disk stars begins near (102, 65) = -0.1 mag (black-body Te = 2800). The young disk variables show a well-defined period-temperature relation.

The space motions indicate that the brightest red stars are about equally divided between young and old disk populations.


Access to the data and references

Asiago Database on Photometric System (ADPS)

Indices and Parameters

M102, C65-62, C102-65


Transmission curves


RCA 7102
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Last update: 21 May 1996