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Abundance analysis of prime B-type targets for asteroseismology. II. B6-B9.5 stars in the field of view of the CoRoT satellite
Context: Aims: The main goal of the ground-based seismologysupport program for the CoRoT mission was to obtain photometric andspectroscopic data for stars in the fields monitored by the satellite.These ground-based observations were collected in the GAUDI archive.High-resolution spectra of more than 200 B-type stars are available inthis database, and about 45% of them is analysed here. Methods:To derive the effective temperature of the stars, we used photometricindices. Surface gravities were obtained by comparing observed andtheoretical Balmer line profiles. To determine the chemical abundancesand rotational velocities, we used a spectrum synthesis method, whichconsisted of comparing the observed spectrum with theoretical ones basedon the assumption of LTE. Results: Atmospheric parameters,chemical abundances, and rotational velocities were determined for 89late-B stars. The dominant species in their spectra are iron-peakelements. The average Fe abundance is 7.24 ± 0.45 dex. Theaverage rotational velocity is 126 km s-1, but there are 13and 20 stars with low and moderate V sin i values, respectively. Theanalysis of this sample of 89 late B-type stars reveals many chemicallypeculiar (CP) stars. Some of them were previously known, but at least 9new CP candidates, among which at least two HgMn stars, are identifiedin our study. These CP stars as a group exhibit V sin i values lowerthan the stars with normal surface chemical composition.Atmospheric parameters and abundance analysis results are only availablein electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/506/213 The CoRoT spacemission was developed and is operated by the French space agency CNES,with participation of ESA's RSSD and Science Programmes, Austria,Belgium, Brazil, Germany, and Spain. Tables [see full textsee full text]and [see full textsee full text] are only available in electronic format http://www.aanda.org
| An Einstein Observatory SAO-based catalog of B-type stars
About 4000 X-ray images obtained with the Einstein Observatory are usedto measure the 0.16-4.0 keV emission from 1545 B-type SAO stars fallingin the about 10 percent of the sky surveyed with the IPC. Seventy-fourdetected X-ray sources with B-type stars are identified, and it isestimated that no more than 15 can be misidentified. Upper limits to theX-ray emission of the remaining stars are presented. In addition tosummarizing the X-ray measurements and giving other relevant opticaldata, the present extensive catalog discusses the reduction process andanalyzes selection effects associated with both SAO catalog completenessand IPC target selection procedures. It is concluded that X-rayemission, at the level of Lx not less than 10 exp 30 ergs/s, is quitecommon in B stars of early spectral types (B0-B3), regardless ofluminosity class, but that emission, at the same level, becomes lesscommon, or nonexistent, in later B-type stars.
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| Сазвежђа: | Једнорог |
| Ректацензија: | 06h52m12.15s |
| Deклинација: | -05°38'43.4" |
| Apparent магнитуда: | 7.251 |
| Даљина: | 518.135 parsecs |
| Proper motion RA: | -0.3 |
| Proper motion Dec: | -0.8 |
| B-T magnitude: | 7.194 |
| V-T magnitude: | 7.247 |
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