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Keck Infrared Spectroscopy of WZ Sagittae: Detection of Molecular Emission from the Accretion Disk
Time-resolved IR spectroscopy of WZ Sge was obtained using NIRSPEC onKeck II. We detect CO and H2 emission from the accretiondisk, placing WZ Sge in a rarefied class of astronomical objectsincluding young stellar objects and high-luminosity early-type stars.During the eclipse phase, the molecular emission greatly weakens, but nofirm evidence for the secondary star is seen, allowing new limits on itsluminosity to be determined. The detection of molecular emissionprovides physical properties T=3000 K andnH>1010 cm-3 within the outer disk.Such a cool, dense region not associated with areas of H I and He Iemission provides the first observational confirmation of predictionsmade by accretion disk models.
| Stars with ISM Polarization Observed with HPOL. II
Polarization data are given for stars whose polarizations are mostlyinterstellar which were observed with the University of Wisconsinspectropolarimeter (HPOL) during 1995-2003. Several cases are found forwhich K in the Serkowski Law for ISM polarization is higher than allowedby published formulas.
| New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
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Osservazione e dati astrometrici
| Costellazione: | Cigno |
| Ascensione retta: | 20h04m25.79s |
| Declinazione: | +42°11'54.2" |
| Magnitudine apparente: | 8.33 |
| Distanza: | 334.448 parsec |
| Moto proprio RA: | 0.3 |
| Moto proprio Dec: | -0.4 |
| B-T magnitude: | 8.21 |
| V-T magnitude: | 8.321 |
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