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Physics of Magnetic Stars, 2007, pp. 102­104

Rotation and kinematics for a sample of new magnetic stars
D. O. Kudryavtsev1 , I.I. Romanyuk1 , E. A. Semenko1 , G.A. Solov'ev
1 2

2

Special Astrophysical Observatory of the Russian AS, Nizhnij Arkhyz 369167, Russia Stavropol State University, ul. Pushkina, 1, Stavropol, Russia

Abstract. The sp ectra taken with the 6 m telescop e are used to determine the radial velo cities and pro jected rotational velo cities for 32 newly discovered magnetic CP stars. Eight of them are found or confirmed to b e binary and binarity is susp ected for another four stars. Six ob jects are memb ers of op en clusters and asso ciations of various age.

1

Intro duction

An extensive program of the search for new magnetic stars is now carried out at the 6-m telescop e of the Sp ecial Astrophysical Observatory of the Russian Academy of Sciences (Kudryavtsev et al. 2006). We suggested a new efficient technique to search for such stars, which allowed us to discover more than 70 such ob jects in a relatively short time (ab out five years). Our observational data -- Zeeman sp ectra taken within the framework of the program for the search for new magnetic stars can b e used for determination of radial velo cities (V r ) and pro jected rotational velo cities (v e sin i).

2

Observations and data reduction

Observations were made in 2000­2005 with the Main Stellar Sp ectrograph of the 6 m telescop e equipp ed with 1160 â 1040 and 2000 â 2000 CCDs. We reduced the data using the LONG context of ESO MIDAS environment and programs develop ed by Kudryavtsev (2000). ° We to ok our sp ectra in the wavelength interval 4450­4650 A with sp ectral resolution R 15000. Note, that the lower limit for the pro jected rotational velo city (v e sin i) which can b e achieved with our mo derate-resolution sp ectra is equal to 18 km/s. Since an essential part of magnetic stars are slow rotators, we obtain for them only the instrumental profiles of sp ectral lines. We determined the radial velo cities in a standard way by comparing the wavelength of the lines of the ob ject with the computed wavelengths adopted from Vienna Atomic Line Database (VALD)(Kupka et al. 1999). We inferred the radial velo cities from the combined sp ectrum made up by coadding the sp ectra of left and right circular p olarization. We used a hollow-catho de Th­Ar lamp to p erform the wavelength calibration of our sp ectra. Our studies of standard stars demonstrated the correctness of the adopted approach. Our median radial velo city agrees accurately with the published values for all the four standard stars employed. 102


ROTATION AND KINEMATICS FOR A SAMPLE OF NEW MAGNETIC STARS

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3

Results

Table 1 lists the rotation and radial velo cities of the 32 newly-discovered magnetic stars. HIPPARCOS catalog (ESA, 1997) gives the parallaxes and prop er motions for 27 stars of our list. For these stars we determined their space-velo city comp onents in the Cartesian co ordinate system (U, V, W). Table 1. Rotation and kinematics of 32 magnetic CP stars HD 2957 5601 6757 9147 19712 27404 34162 34719 36955 38823 39082 39658 40711 40759 41403 43819 47756 49040 66350 115606 142554 149822 151199 158450 169842 170973 178892 184471 196606 205087 207188 343872 ve sin i km/s 27 ± 3 22 ± 2 18 23 ± 2 42 ± 3 37 ± 3 23 ± 2 49 ± 6 37 ± 3 20 ± 2 60 ± 2 32 ± 5 20 ± 2 25 ± 3 28 ± 3 18 28 ± 2 24 ± 2 30 ± 2 22 ± 2 27 ± 2 64 ± 2 55 ± 2 20 ± 2 50 ± 7 18 18 18 42 ± 3 25 ± 2 43 ± 3 20 ± 2 VR km/s +11.0 ± 1.4 +11.2 ± 2.1 -6.5 ± 1.5 -30 var +17.6 ± 1.3 +10.0 ± 3.3 +36.7 ± 1.3 +16 var +27.8 ± 2.8 -8.5 ± 1.2 +25.2 ± 1.2 -5.6 ± 1.1 -16.2 ± 4.4 +33.1 ± 1.9 +0.9 ± 0.4 +49.0 ± 1.0 +20.8 ± 1.4 +20.7 ± 0.4 +28.4 ± 1.1 -18.3 ± 1.9 -31.9 ± 1.6 +20.8 ± 3.4 -51.9 ± 2.8 -17.2 ± 1.4 -30.8 ± 2.9 -11.7 ± 1.4 -19.4 ± 1.0 -35 var -17 var -10.7 ± 0.7 -8.1 ± 2.1 -10.0 ± 1.1 U km/s 7.2 -18.1 0.4 5.9 14.6 5.5 -16.4 13.6 -25.1 20.6 -9.0 -0.2 11.1 20.0 14.6 33.4 -33.9 22.6 1.8 17.9 6.5 -17.7 -13.9 1.5 14.0 8.3 V km/s 9.4 6.0 6.1 -20.1 -8.4 -0.3 21.0 2.0 13.6 1.9 20.9 9.7 5.7 -20.0 -4.8 -6.9 2.5 -5.7 -11.9 -3.2 16.3 -20.9 -26.2 -3.4 2.2 8.5 W km/s -2.3 -3.6 -8.1 -0.7 -24.0 2.6 -0.3 2.3 11.3 -7.4 -21.7 -1.9 0.8 -7.9 9.6 -4.8 20.4 -49.0 3.8 4.0 -5.9 -5.7 -12.2 0.1 -4.2 3.0

We determined radial and rotational velo cities for 32 new magnetic stars. It was the first stage of an extensive program aimed at the study of the space distribution, kinematics and physics of magnetic stars in our Galaxy. The stars studied b elongs to the most numerous classes of CP stars with Si, Si+ and SrCrEu anomalies. Earlier, magnetic stars of this typ e were observed only in the immediate vicinity of the Sun (at helio centric distances of up to 100­200 p c). Our new sample features more distant ob jects.


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Of the 32 new magnetic stars 14 have parallaxes smaller than 4 mas and five more ob jects have no parallaxes determined by HIPPARCOS satellite (ESA, 1997). Given that they are faint ob jects of 9­10th magnitude, it is safe to assume that they are lo cated at the helio centric distances greater than 250 p c. Eight out of the total numb er of these stars are binary and four other stars are susp ected binaries. Hence, the fraction of binaries somewhat exceeds the common 20 % level for magnetic stars. Six ob jects are memb ers of op en clusters and asso ciations of various age. Their detailed study is of sp ecial interest for understanding of origin and evolution of stellar magnetism.
Acknowledgements. This work was supported by the Russian Foundation For Basic Research (grant No. 06-02-16110a) and the Russian Science Support Foundation.

References
ESA, 1997, The Kupka F., Ryab Kudryavtsev D. Kudryavtsev D. HIPPARCOS catalog, ESA SP-1200 chikova T. A., Piskunov N. E., et al., 1999, Astron. Astrophys. Suppl. Ser., 130, 119 O., 2000, Baltic Astron., 9, 649 O., Romanyuk I.I., Elkin V. G., Paunzen E., 2006, Mon. Not. R. Astron. Soc., 372, 1804