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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| 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
| Scattering and absorption in soft X-ray selected AGN: an optical polarization survey
We have surveyed the optical linear polarization of a completelyidentified sample of 43 bright soft-X-ray-selected ROSAT AGN. Most (40)of these AGN show low polarization (~1%), and no clear opticalreddening. This supports the suggestion from rapid X-ray variability,disk-like spectral energy distributions, and lack of cold X-rayabsorption, that we are viewing a bare AGN disk. IRASF12397+3333 andIRAS13349+2438 show high polarization increasing to the UV - clearevidence for scattering. As well as steep, soft-X-ray spectra, they showoptical reddening and rapid X-ray variability, but almost no cold X-rayabsorption - a combination that suggests dusty ionized gas along theline-of-sight. Brandt et al. suggested and found these `warm absorbers'for IRAS13349+2438. IRASF12397+3333 is a new candidate. Combining ourdata with the optical and X-ray spectra of the high polarizationnarrow-line Seyfert 1 nuclei (NLSy1s) investigated by Goodrich revealsstrong correlations among optical reddening indicators (alpha_opt andHα /Hβ ), [OIII]/Hβ_b , and cold intrinsic X-rayabsorption Delta N_H. Optical reddening underpredicts the cold X-rayabsorption, suggesting dusty warm absorbers in all the highly polarizedAGN. The existence of these scattering-polarized and reddened NLSy1ssuggests an orientation Unified Scheme within the class of NLSy1s,analogous to that linking Seyfert 1 and Seyfert 2 nuclei. For somehighly polarized and optically selected AGN we present new analysis ofarchival X-ray data, and for the highly polarized AGN new opticalspectroscopy is presented in an appendix.
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | דרקון |
| התרוממות ימנית: | 12h31m53.98s |
| סירוב: | +72°10'44.0" |
| גודל גלוי: | 8.049 |
| מרחק: | 242.131 פארסק |
| תנועה נכונה: | -5.2 |
| תנועה נכונה: | 14 |
| B-T magnitude: | 8.303 |
| V-T magnitude: | 8.07 |
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