Galactic Distribution of Supergiants.

Abstract

A summary of photometric and spectroscopic data for stars later than class B5 and more luminous than absolute visual magnitude -4 has been compiled in Mount Stromlo Mimeogram No. 8. Included are the HD number with other designations for nearly 1000 stars, with radial velocity (available for 50% of entries), visual magnitude, spectral classification on the MK system (or for Cepheids the period of pulsation), the assumed absolute magnitude, the color excess from multicolor photoelectric photometry, and an estimate of distance (again for just 50% of the stars). Variable stars believed to be associated with the halo population (such as RV Tauri, semiregular and some Cepheids) are specifically excluded, usually because the available data are too incomplete to present statistics on a comparable basis. Although the incompleteness of detection of non- variable supergiants even to 9th magnitude, and of Cepheids to 13th magnitude, vary considerably over the sky, the distribution with galactic longitude is given. Broad frequency minima in all spectral types are noted at 2150 and 3320, and narrower ones at 350, 950, 1530, 2560, and 2720. L" 136-B9 A F G K M Cep. 0-60 8 8 19 16 4 1 63 60 120 28 59 36 23 24 6 89 120 180 35 43 17 11 18 17 58 180 240 9 15 12 11 6 6 55 240 300 4 13 30 9 8 11 122 300 360 4 4 7 4 2 1 62 Grateful acknowledgment is made to the hospitality of Professor J. Landi Dessy at Cordoba, where most of the literature search was carried out. Mrs. E. R. Wilkie has given valuable assistance in arranging the list of stars.