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Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
| Far-ultraviolet stellar photometry: A field in Orion
Far-ultraviolet photometry for 625 objects in Orion is presented. Thesedata were extracted from electrographic camera images obtained duringsounding rocket flights in 1975 and 1982. The 1975 images were centeredclose to the belt of Orion while the 1982 images were centeredapproximately 9 deg further north. One hundred and fifty stars fell inthe overlapping region and were observed with both cameras. Sixty-eightpercent of the objects were tentatively identified with known starsusing the SIMBAD database while another 24% are blends of objects tooclose together to separate with our resolution. As in previous studies,the majority of the identified ultraviolet sources are early-type stars.However, there are a significant number for which no such identificationwas possible, and we suggest that these are interesting objects whichshould be further investigated. Seven stars were found which were brightin the ultraviolet but faint in the visible. We suggest that some ofthese are nearby white dwarfs.
| Observations of narrow diffuse interstellar bands toward stars with low reddening
The equivalent widths of the 5780-A, 5797-A, and 6613-A diffuseinterstellar bands (DIBs) toward 22 stars with E(B-V) less than 0.1 aredetermined on the basis of observations obtained with a coudespectrograph and Si-photodiode array on the 2.7-m telescope at McDonaldObservatory during June, November, and December, 1982. The results arepresented in sample spectra, tables, and graphs and discussed inrelation to the N(H2) data of Savage et al. (1977). All three bands arefound to be 2-3 times stronger for the group of objects with N(H2)greater than 10 to the 18th/sq cm than for the group with smaller N(H2).Since this observation suggests a molecular origin for the DIBs, but theabundance data argue against a gas-phase molecular carrier, the DIBs areattributed to grain-surface impurity-site/molecular-complexinteractions. The proximity of the DIBs to the velocity of the majoratomic components is held to rule out the grain-sputtering hypothesis ofSmith et al. (1977).
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