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The Pul-3 catalogue of 58483 stars in the Tycho-2 system
A catalogue of positions and proper motions of 58483 stars (Pul-3) hasbeen constructed at the Pulkovo observatory. The Pul-3 is based on theresults of measurements of photographic plates with galaxies (Deutsch'splan). All plates were taken using the Pulkovo Normal Astrograph (thefirst epoch is in the 1950s and the second epoch is in the 1970s).The Pul-3 catalogue contains stars of mainly 12 to 16.5 mag in 146fields with galaxies in the declination zone from -5o to+85o. The Tycho-2 has been used as a reference catalogue.The mean epoch of the Pul-3 is 1963.25. The internal positional accuracyof the Pul-3 catalogue at the mean epoch of observations is ±80mas. The accuracy of the proper motions is mostly within ±3mas/yr to ±12 mas/yr. Comparisons of the Pul-3 with Tycho-2 andARIHIP have been done at the mean epoch of the Pul-3. The Pul-3 externalpositional accuracy relative to Tycho-2 is ±150 mas.The catalogue is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/357
| Discovery of New Candidate Vega-type Systems from IRAS and the 2 Micron All-Sky Survey
We obtained J (1.25 μm), H (1.65 μm), and Ks (2.17μm) photometry from the 2 Micron All-Sky Survey and 12, 25, 60, and100 μm photometry from the IRAS Faint Source Catalog of 2834 fieldstars. We identified in this sample 296 main-sequence (luminosity classIV, IV-V, or V) stars. We searched the sample of main-sequence stars forexcess 12 μm emission with respect to J, H, and Ksphotospheric emission. We discovered eight systems with 12 μm excessemission newly reported here. These excesses are likely to be fromVega-type circumstellar dust, but small-aperture photometry is needed toconfirm their nature. Preliminary models that assume the excesses arecircumstellar show the dust to be located ~1-10 AU from the stars, whereit is heated to ``terrestrial'' temperatures, ~200-500 K. Colder dustmight also exist in the systems but below the IRAS sensitivity limit.The exception is HD 93331 (B9.5 V), previously known for its IRASfar-infrared excess.
| The Vienna-KPNO search for Doppler-imaging candidate stars. I. A catalog of stellar-activity indicators for 1058 late-type Hipparcos stars
We present the results from a spectroscopic Ca ii H&K survey of 1058late-type stars selected from a color-limited subsample of the Hipparcoscatalog. Out of these 1058 stars, 371 stars were found to showsignificant H&K emission, most of them previously unknown; 23% withstrong emission, 36% with moderate emission, and 41% with weak emission.These spectra are used to determine absolute H&K emission-linefluxes, radial velocities, and equivalent widths of theluminosity-sensitive Sr ii line at 4077 Ä. Red-wavelengthspectroscopic and Strömgren y photometric follow-up observations ofthe 371 stars with H&K emission are used to additionally determinethe absolute Hα -core flux, the lithium abundance from the Li i6708 Å equivalent width, the rotational velocity vsin i, theradial velocity, and the light variations and its periodicity. Thelatter is interpreted as the stellar rotation period due to aninhomogeneous surface brightness distribution. 156 stars were found withphotometric periods between 0.29 and 64 days, 11 additional systemsshowed quasi-periodic variations possibly in excess of ~50 days. Further54 stars had variations but no unique period was found, and four starswere essentially constant. Altogether, 170 new variable stars werediscovered. Additionally, we found 17 new SB1 (plus 16 new candidates)and 19 new SB2 systems, as well as one definite and two possible new SB3systems. Finally, we present a list of 21 stars that we think are mostsuitable candidates for a detailed study with the Doppler-imagingtechnique. Tables A1--A3 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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| Takýmyýldýz: | Buyuk Ayi |
| Sað Açýklýk: | 09h29m13.96s |
| Yükselim: | +68°46'05.2" |
| Görünürdeki Parlaklýk: | 9.067 |
| özdevim Sað Açýklýk: | 34.2 |
| özdevim Yükselim: | 6 |
| B-T magnitude: | 10.38 |
| V-T magnitude: | 9.176 |
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