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β Cephei stars in the ASAS-3 data. II. 103 new β Cephei stars and a discussion of low-frequency modes
Context: The β Cephei stars have been studied for over a hundredyears. Despite this, many interesting problems related to this class ofvariable stars remain unsolved. Fortunately, these stars seem to bewell-suited to asteroseismology. Hence, the results of seismic analysisof β Cephei stars should help us to better understand pulsationsand the main sequence evolution of massive stars, particularly theeffect of rotation on mode excitation and internal structure. It istherefore extremely important to increase the sample of known βCephei stars and select targets that are useful for asteroseismology. Aims: We analysed ASAS-3 photometry of bright early-type stars with thegoal of finding new β Cephei stars. We were particularly interestedin β Cephei stars that would be good for seismic analysis, i.e.,stars that (i) have a large number of excited modes; (ii) showrotationally split modes; (iii) are components of eclipsing binarysystems; (iv) have low-frequency modes, that is, are hybrid βCephei/SPB stars. Methods: Our study was made with a homogeneous sampleof over 4100 stars having MK spectral type B5 or earlier. For thesestars, the ASAS-3 photometry was analysed by means of a Fourierperiodogram. Results: We have discovered 103 β Cephei stars,nearly doubling the number of previously known stars of this type. Amongthese stars, four are components of eclipsing binaries, seven have modesequidistant or nearly equidistant in frequency. In addition, we foundfive β Cephei stars that show low-frequency periodic variations,very likely due to pulsations. We therefore regard them as candidatehybrid β Cephei/SPB pulsators. All these stars are potentially veryuseful for seismic modeling. Moreover, we found β Cephei-typepulsations in three late O-type stars and fast period changes in one, HD168050.Table 2 and Figs. 2-14 are only available in electronic form athttp://www.aanda.org The V photometry for all 103 stars is available inelectronic 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/477/917
| New Estimates of the Solar-Neighborhood Massive Star Birthrate and the Galactic Supernova Rate
The birthrate of stars of masses >=10 Msolar is estimatedfrom a sample of just over 400 O3-B2 dwarfs within 1.5 kpc of the Sunand the result extrapolated to estimate the Galactic supernova ratecontributed by such stars. The solar-neighborhood Galactic-plane massivestar birthrate is estimated at ~176 stars kpc-3Myr-1. On the basis of a model in which the Galactic stellardensity distribution comprises a ``disk+central hole'' like that of thedust infrared emission (as proposed by Drimmel and Spergel), theGalactic supernova rate is estimated at probably not less than ~1 normore than ~2 per century and the number of O3-B2 dwarfs within the solarcircle at ~200,000.
| New runaway OB stars with HIPPARCOS
A Monte Carlo method for detection of runaway OB stars fromobservational data is proposed. 61 runaway OB star candidates have beendetected by an analysis of Hipparcos proper motions. The peculiartangential and total transverse velocities have been determined forthese stars. A list of the detected runaway star candidates ispresented. The evidence of a discrepancy between photometric andparallactic distances of runaway OB star candidates is presented.
| Catalog of Galactic OB Stars
An all-sky catalog of Galactic OB stars has been created by extendingthe Case-Hamburg Galactic plane luminous-stars surveys to include 5500additional objects drawn from the literature. This work brings the totalnumber of known or reasonably suspected OB stars to over 16,000.Companion databases of UBVβ photometry and MK classifications forthese objects include nearly 30,000 and 20,000 entries, respectively.
| Astrometric positions of stars associated with nebulosities in the southern hemisphere.
Several stars associated with nebulosities and cited by S. van den Berghand W. Herbst are included in the preliminary programme for theHIPPARCOS mission. When performing preparatory measurements of plates,we encountered difficulties in identifying certain of these objects whenrelying only on coordinates, which led us to take advantage of thiswork, which relates to the southern sky, in order to determine theastrometric position of all the objects in the list, to within 0.35''.This catalogue is available from the Centre for Astronomic Data atStrasbourg.
| Catalog of multiple Trapezium type systems
Not Available
| R associations. I - UBV photometry and MK spectroscopy of stars in southern reflection nebulae
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975AJ.....80..212H&db_key=AST
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| Сазвежђа: | Олтар |
| Ректацензија: | 17h04m01.23s |
| Deклинација: | -51°05'01.1" |
| Apparent магнитуда: | 8.349 |
| Даљина: | 10000000 parsecs |
| Proper motion RA: | -6.1 |
| Proper motion Dec: | -4 |
| B-T magnitude: | 8.335 |
| V-T magnitude: | 8.348 |
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