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Multi-site, multi-technique survey of γ Doradus candidates. I. Spectroscopic results for 59 stars
We present the first results of a 2-year high-resolution spectroscopycampaign of 59 candidate γ Doradus stars which were mainlydiscovered from the HIPPARCOS astrometric mission. More than 60% of thestars present line profile variations which can be interpreted as due topulsation related to γ Doradus stars. For all stars we alsoderived the projected rotation velocity (up to more than 200 kms-1). The amplitude ratios 2K/Δ m for the mainHIPPARCOS frequency are in the range 35-96 kms-1,mag-1. About 50% of the candidates arepossible members of binary systems, with 20 stars being confirmedγ Doradus. At least 6 stars present composite spectra, and in allbut one case (for which only one spectrum could be obtained), the narrowcomponent shows line profile variations, pointing towards anuncomfortable situation if this narrow component originates from a shellsurrounding the star. This paper is the first of a series concerningmode identification using both photometric and spectroscopic methods forthe confirmed γ Doradus stars of the present sample.Partially based on observations obtained at the Observatoire deHaute-Provence.
| Multi-color Polarimetry of the Dust Disk Candidate BD+31 degrees 643
The tentative detection of a dust disk around the main-sequence star BD+31 deg643 was recently announced by Kalas & Jewitt and representsonly the second such object ever to be imaged. Here, we presentmultiband visual polarimetry of this object. Our single-aperturepolarimetry also strongly suggests the presence of a disk. We find thatthe poles of the disk are oriented parallel to the polarization of themajority of background sources in the region and, hence, probably to themagnetic field in the cloud, as would be expected from star formationtheory. The polarization observed toward BD +31 deg643 can be modeled asa combination of Rayleigh scattering from material in the polar regionsof the disk and a term due to the disk itself.
| Interstellar extinction in the direction of the open cluster IC 348 and the Per OB2 association
The relationship between interstellar extinction and distance in thedirection of dark clouds in the areas around the open cluster IC 348 andthe association Per OB2 is determined using the results of photoelectricphotometry of 189 stars in the Vilnius photometric system. Two absorbinglayers are found. The nearest layer, covering the whole area around IC348, shows the mean extinction A(V) of about 0.7 mag. It begins at thedistance of 160 pc and probably is an extension of the Taurus darkclouds to the northwest. The second absorbing layer has the form of achain of dark condensations named L1468, L1470, and L1471 and is at 260pc distance. This layer has a higher density, its mean extinction beingabout 2.0 mag. The cluster IC 348 is at about the same distance and isphysically related to the dark cloud L1470. The distance of the Per OB2association is found to be 340 pc and the mean extinction of its membersis 0.95 mag. A model of the spatial distribution of the Perseus andTaurus dark clouds based on photometric distance determinations in thisand previous papers is proposed. Six stars in the IC 348 area aresuspected to have emission in the H-alpha line.
| Uvbyβ Photometry of Stars in the Direction of the Association Perseus OB 2
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971PASP...83..656R&db_key=AST
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| Takýmyýldýz: | Kahraman |
| Sað Açýklýk: | 03h50m27.51s |
| Yükselim: | +31°33'13.0" |
| Görünürdeki Parlaklýk: | 8.554 |
| Uzaklýk: | 201.613 parsek |
| özdevim Sað Açýklýk: | 5.6 |
| özdevim Yükselim: | -6.6 |
| B-T magnitude: | 8.881 |
| V-T magnitude: | 8.581 |
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