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A catalogue of multiplicity among bright stellar systems
We consider the multiplicity of stellar systems with (combined)magnitude brighter than 6.00 in Hipparcos magnitudes. We identify 4559such bright systems (including the Sun), and the frequencies ofmultiplicities 1, 2,..., 7 are found to be 2718, 1437, 285, 86, 20, 11and 2. We discuss the uncertainties, which are substantial. We alsoconsider the distributions of periods of orbits and suborbits. We notethat for even more restricted set of 478 systems with VH<= 4.00, the proportions of higher multiples up to sextuple areprogressively larger (213, 179, 54, 19, 8, 5), suggesting substantialincompleteness in even the reasonably well studied larger sample.This sample can be seen as relatively thoroughly studied formultiplicity, and reasonably representative of stars more massive thanthe Sun. But the restriction to VH <= 6 means that oursample contains hardly any systems where all components are low-massmain-sequence stars (K or M).Data on multiplicity are important as a constraint on (i) the starformation problem, (ii) the problem of the evolution of the Galacticstellar population and (iii) the interaction of dynamics and evolutionthrough the effect of Kozai cycles. We discuss these topics briefly.
| Broad-band photometry of selected southern ultraviolet-bright stars.
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| Optical observations of ultraviolet objects. I - Spectral classification of 103 stars /l = 200-275 deg/
Results are presented of a program of spectral classification of 103stars originally selected as ultraviolet objects from TD-1 satellitephotometry with the S2/68 experiment. Most of the objects appear to bespectroscopically normal stars; the method of selection yielded a sampleof relatively unreddened B stars at distances up to about 2 kpc. Thisresult is compared with recent studies of the spatial distribution ofinterstellar extinction in the same regions of the sky.
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