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Einstein Observatory survey of X-ray emission from solar-type stars - The late F and G dwarf stars
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| An empirical H-gamma luminosity calibration for class V-III stars
The W(H-gamma)-M(v) relation for spectral types O to early A of theluminosity classes III-V is calibrated, on the basis of highsignal/noise Reticon spectra for 87 members of eight open clusters andassociations as well as 37 reliable parallax stars, to a mean probabledispersion of + or - 0.28 mag. Although no spectral type corrections arerequired, stellar evolution probably affects the construction of the newcalibration, so care should be exercised in determinations of distancemoduli from slightly evolved cluster sequences. Systematic departuresfrom the calibration may be present for stars with V sin i not less than220-250 km/sec. A comparison of the new calibration with otherearly-type ones shows that it is 1.2 mag brighter than Petrie's (1965)H-gamma calibration at spectral type O6, and 0.7 mag brighter at A3.
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Osservazione e dati astrometrici
| Costellazione: | Cassiopea |
| Ascensione retta: | 00h05m05.95s |
| Declinazione: | +57°46'13.2" |
| Magnitudine apparente: | 8.218 |
| Moto proprio RA: | 33.4 |
| Moto proprio Dec: | 73.1 |
| B-T magnitude: | 8.807 |
| V-T magnitude: | 8.267 |
Cataloghi e designazioni:
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