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Radial velocity measurements. IV - Ground-based accompaniment to the HIPPARCOS observation program
The paper presents 396 radial velocities of stars distributed in 19fields of 4 x 4 degrees. The study employs the Fehrenbach objectiveprism method and the same measuring technique used in a previous paper(Fehrenbach et al., 1987).
| On the origin and distribution of C IV and SI IV ions in the neighboring interstellar medium
IUE spectrometer observational data are reported on the C IV, Si IV, andN V absorption lines in 46 distant stars at FWHM resolution of 30km/sec. A simple analytic theory is given for these contributions,including the effects of ionization by a soft X-ray background. Whilefor some of the most distant field stars a photoionized contribution maybe ruled out, C IV absorption lines are detected which are shallow andbroad. It is suggested that what are being detected in these cases arecontributions from the hot interstellar gas that is responsible for theO VI absorption lines. Most of the Si IV and C IV lines probably arisein the H II regions surrounding the observed star or its neighbors.
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Osservazione e dati astrometrici
| Costellazione: | Cigno |
| Ascensione retta: | 20h28m48.71s |
| Declinazione: | +45°43'07.8" |
| Magnitudine apparente: | 7.384 |
| Distanza: | 303.03 parsec |
| Moto proprio RA: | 8.4 |
| Moto proprio Dec: | -4.5 |
| B-T magnitude: | 7.362 |
| V-T magnitude: | 7.383 |
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