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Magnetic stars, 2004, 247-249

Study of magnetic fields of different luminosity hot stars
Butkovskaya V., Plachinda S.
Crimean Astrophysical Observatory, Nauchny, Crimea, 98409, Ukraine

Abstract. Circular sp ectrop olarimetric observations of four different luminosity hot stars were obtained in an attempt to detect magnetic fields via longitudinal ° Zeeman effect in the sp ectral line HeI 6678.149 A: Pegasi (Sp B2 IV), Orionis (Sp B2 I I I), Orionis (Sp B3 I I Ie), Persei (Sp B1 Ib). No statistically significant values of the mean magnetic field were detected. The pulsation p erio d of Pegasi was refined as P = 0d 151750393 ± 6.4 в 10-8 . . Key words: stars: magnetic fields stars: pulsations

Circular spectropolarimetric observations of four different luminosity hot stars were obtained in an attempt to detect magnetic fields via longitudinal Zeeman effect in the spectral line HeI 6678.149 ° Stars were selected A. to sample over the range of spectral types from B1 to B3 and of luminosity types from I to IV: Pegasi (HR 39; HD 886; B2 IV), Orionis (HR 1790; HD 35468; B2 III), Orionis (HR 1934; HD 37490; B3 III), Persei (HR 1203; HD 24398; B1 Ib). In Figure 1 one can see an example of the profile of the line HeI 6678.149 ° normalized to the continuum A in the spectrum of Pegasi. The restriction level of the used part of the contour is shown by the straight line. Pegasi is one of the Cephei (or Canis Ma joris) type stars. This star displays the visual light curve with the amplitude V 0.017, radial velocity curve with the amplitude 2K 7.0 (k m sec -1 ) and with the pulsation period P = 0d 15175020 ± 4 в 10-8 , which is comparable to the periods of other Cephei-type . variable stars (Ducatel et al. 1981). In order to add a new sample of velocity measurements for Pegasi, 178 exposures were made during 5 nights. The duration of the set of radial velocity measurements per night was more than the pulsation period of the star. For period calculation our data were complemented by data of McNamara (1955), Sandberg et. al. (1960), Ducatel et al. (1981). A single pulsation period was found using Martin Sperl's program "Period98" : HJD
max

= 2451060.4614 + n0d 151750393 ± 6.4 в 10 .

-8

.

(1)

The radial velocity values as a functions of phases of the pulsation period of Pegasi are given in Figure 2. The mean radial velocities per night are subtracted from each radial velocity value. The mean values per night of the longitudinal magnetic field and radial velocity are presented in Table 1.

References
Ducatel D., Le Contel J.-M., Sareyan J.-P., Valtier J.-C., 1981, Astron. Astrophys. Suppl. Ser., 43, 359 Sandberg H.E., Mc.Namara D.H., 1960, Publ. Astr. Soc. Pacific, 72, 508 McNamara D.H., 1955, Astrophys. J., 122, 95

c Sp ecial Astrophysical Observatory of the Russian AS, 2004

248

BUTKOVSKAYA, PLACHINDA

1 .0 0 .9 0 .8 0 .7 0 .6 0 .5 0 .4 6676

0.87

r

6678

6680

Wavelenght (е)

Figure 1: The profile of the line HeI 6678.149 ° in the spectrum of Pegasi, which was observed on 1998 A September 3, normalized to the continuum.

59 NP HF V

Ў

3KDVH

Figure 2: The radial velocity curve of Pegasi.

STUDY OF MAGNETIC FIELDS OF DIFFERENT...

249

Table 1: Results of measurements of magnetic fields and radial velocities JDH (+2400000.000) 50681.516 50684.495 50802.318 51060.481 51061.480 51088.430 51172.251 51488.272 52217.366 51171.223 51172.256 51486.424 51487.522 51488.512 52280.261 51489.610 51502.514 50692.481 51522.347 52280.184 52624.192 52625.219 Set Be ± (hours) (Gauss) Pegasi (Sp B2 IV) 1.05 -7.70 ± 5.55 3.02 -2.56 ± 3.59 1.08 -6.48 ± 9.07 5.17 -4.97 ± 6.28 5.40 10.51 ± 4.83 4.53 0.75 ± 5.96 4.93 4.97 -2.66 ± 4.08 5.45 Orionis (Sp B2 III) 0.67 2.78 1.80 10.37 ± 18.33 5.33 -28.32 ± 14.15 6.02 -11.55 ± 7.39 1.83 80.28 ± 32.08 Orionis (Sp B3 IIIe) 1.42 -14.89 ± 183.32 5.67 31.77 ± 117.00 Persei (Sp B1 Ib) 1.83 8.61 ± 15.04 2.58 -72.44 ± 37.14 1.58 83.15 ± 90.30 1.67 81.76 ± 29.73 1.42 114.79 ± 51.10 Vr (km sec 2.27 3.71 3.11 1.86 3.52 19.59 18.76 17.96 17.29 17.93 ± ± ± ± ± 17.67 ± 0.23 21.51 ± 0.07 21.36 ± 0.09 0.18 0.001 0.11 0.03 0.06
-1

)