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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.
| A study of galactic structure in a region of Puppis
Galactic structure and rotation in the region of the Puppis OB 1 and OB2 associations are investigated on the basis of spectrophotometric andkinematic observations. Data was obtained from measurements of platestaken at the ESO objective prism astrograph at a spectral dispersion of110 A/mm. Spectral types, B magnitudes, distance moduli andgalactocentric distances are presented for 102 stars, including 74 oftypes O5 through B3 and the remainder of types B5 and B6, and radialvelocities determined by Fehrenbach's method as well as derived circularvelocities are presented for 63 OB stars. The results demonstrate thereality of the Pup OB 1 association, which is found at a distancemodulus of 12.20 with a mean radial velocity of 37 km/sec. The physicalreality of the Pup OB 2 association, however, appears doubtful, due tothe spread of the more distant group of OB stars (distance modulus13.45, mean radial velocity 57 km/sec) over a distance of more than 3kpc; this more distant group, as well as the H II region S 311, areassigned to an extension of the Perseus arm. The galactic rotation curvederived is found to exhibit a clear rise for galactocentric distancesgreater than 12.5 kpc.
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