2024 II/24 H-{Alpha} Phot Late-Type Stars I. Northern F, G, K Stars D W Peat Mon. Not. R. Astron. Soc. 128 435 1964 1964MNRAS.128..435P Photometry, H-alpha Stars, late-type Stars, dwarfs Observations are presented of the strength of the H-{alpha} absorption line in the spectra of approximately 600 northern F, G and K stars of differing luminosities and chemical compositions. Most of the stars in this catalogue were previously observed by Griffin and Redman (1960), Deeming (1960), and Griffin (1961). Data given in this catalog include HD number, MKK spectral classification, high velocity, (B-V) color index, magnesium b ratio, sodium D line ratio and H-{alpha} ratio.

(Peat, 1964) The integrated light-intensity within a band defined by the wavelength limits 6545-6580A, centered on the wavelength of H-{alpha}, was measured by one photomultiplier. The combined integrated light intensity within the two comparison regions defined respectively by the wavelength limits 6477.5 to 6495.0A and 6630.0 to 6647.5A was measured by a second photomultiplier. The wavelengths were monitored using the bright neon emission at lambda 6402 produced by a neon discharge tube, and were held constant to within +-0.5A. Errors of the order of +- 2A in the wavelength setting, however, were found experimentally to have no effect on the results, and corrections for the Doppler shift due to the stellar radial velocity were therefore unnecessary. The "H-{alpha} ratio" R, was defined by the expression R = [B/B(L)]/[A/A(L)] where B, A represent the photomultiplier output counts for a star, in the side bands and H-{alpha} band respectively, and B(L), A(L) represent the corres- ponding counts for the lamp. One might expect this ratio to be partially determined by features, other than H-{alpha}, situated within the central and comparison regions of the stellar spectrum, but examination of a high reso- lution spectrogram of Arcturus (a K2 giant star typical of the stars on the observing program) taken by Griffin (1962) showed that these other features affected the H-{alpha} ratio by less than 0.3%. This is only of the same order as the estimated observational error in the H-{alpha} ratios, and we shall assume therefore that the H-{alpha} ratio is determined solely by the strength of the H-{alpha} absorption line. Griffin (1961) describes the three-channel spectrophotometer with which observations were made at the coude focus of the Cambridge Observatory 36 in reflecting telescope. Griffin and Redman (1959), Deeming (1960), and Griffin (1961) describe the method of Observation and reduction.

HD "HD" --- HDnum HD number of the star --- Sp MKK spectral classification --- lum Luminosity class indication 10: Ia 13: Iab 14: Iab-Ib 15: Ib 17: Ib-II 20: II 25: II-III 30: III 35: III-IV 40: IV 45: IV-V 50: V --- HV High Velocity 'HV' indicates that the star is a high velocity star with a space motion in excess of 63 km/s as determined by Eggen (1962). --- B-V (B-V) color index from Deeming (1960) and Argue (1962) mag Mgb Mg b ratio measured by Deeming (1960) --- NaD Sodium D line ratio measured by Griffin (1961) --- Ha H {alpha} ratio --- ID Star number --- Julie Anne Watko SSDOO/ADC 1996May10 II_24.xml