β Lyrae: on the magnetic field
β Lyrae shows a complicated and intricate time-dependent behaviour of the magnetic field.
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Головна астрономічна обсерваторія НАН України
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| Zitieren: | β Lyrae: on the magnetic field / M. Skulsky, S. Plachinda // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 237-238. — Бібліогр.: 12 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859596129003372544 |
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| author | Skulsky, M. Plachinda, S. |
| author_facet | Skulsky, M. Plachinda, S. |
| citation_txt | β Lyrae: on the magnetic field / M. Skulsky, S. Plachinda // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 237-238. — Бібліогр.: 12 назв. — англ. |
| collection | DSpace DC |
| container_title | Кинематика и физика небесных тел |
| description | β Lyrae shows a complicated and intricate time-dependent behaviour of the magnetic field.
|
| first_indexed | 2025-11-27T21:08:47Z |
| format | Article |
| fulltext |
β LYRAE: ON THE MAGNETIC FIELD
M. Skulsky1, S. Plachinda2
1Lviv Polytechnic National University
12 Bandera Str., 79013 Lviv, Ukraine
e-mail: mysky@polynet.lviv.ua
2Scientific-Research Institute “Crimean Astrophysical Observatory”
Nauchny, 98409 Crimea, Ukraine
e-mail: plach@crao.crimea.ua
β Lyrae shows a complicated and intricate time-dependent behaviour of the magnetic field.
INTRODUCTION
A system of periodicities is observed for the eclipsing binary β Lyrae. The more important and main period is
the orbital period Porb
∼= 12.94d, which is being increased to the value of 18.9 s yr−1 [3] because the brightest
B8 II star (∼ 3M�) losing mass due to a more massive (∼ 13M�) and invisible in the spectrum component,
which surrounded by an accretion disc. A more shorter transient period of 1.85d was observed in the absolute
radiative flux of the Hα emission [1]. P ∼= 4.74d was derived from the radial velocities behaviour of strong
emission lines [2]. There are present the considerably longer periods as well: P = 283d ± 1d, which was
evaluated from the analysis of light curves in [12] and [2], and P ≈ 340d that was evaluated in [6].
OBSERVATIONS
The first extensive study of the magnetic field of the eclipsing binary system β Lyrae was carried out in 1980–1988
using the 6-m telescope of the Special Astrophysical Observatory [8–10]. The Zeeman splitting was measured in
the atmospheric lines of the brightest B8 giant. These photographic observations showed the negative mean value
of the magnetic field equal to −1240 G. An amplitude of the variance versus the orbital period was ∼ ±450 G.
Measurements of Zeeman splitting in the Si II 6347, 6371 Å lines were made in 1991–1992 with the Stokesmeter
and CCD detector, mounted in front of the coude spectrograph of the 2.6-m Shajn telescope at the Crimean
Astrophysical Observatory [11]. The presence of the magnetic field on the primary component was confirmed.
The amplitude of the variability against the orbital period was ∼ ±100 G and the mean value was 0. Since
1993, we have continued the observations studying some lines of metals. Results of photographic measurements
as well as our magnetic field measurements during 1993–1995 and 2000 using a total sample of spectral lines
and results of magnetic field measurements at the Catania Astrophysical Observatory in the summer of 1999
are presented in [4]. The mean value of the measured effective magnetic field in 1999 was +1290 G. Therefore,
the change of the magnetic field on β Lyrae for the long-time-scale variability is 2.5 kG.
All the Crimean observations since 1993 have been reprocessed using the Monte Carlo method of numerical
simulation of standard deviations [7]. Spectral lines which have huge errors of magnetic field measurements
have been eliminated from the sample. Results of the processing of the Crimean observations since 1993 to
2004, of the photographic measurements from 1980 to 1988, and of the Catania observations in 1999 are shown
in Fig. 1. The Crimean observations do not show any periodicity with the orbital period. This period is not
clearly present in the Catania observations of 1999 even by taking into account the 1980s observations.
The multi-periodicity and resonances are observed in the cataclysmic variable stars with the accretion disc
(SU UMa-type dwarf novae). As it is showed in [5] for SU UMa stars, the interconnection between the external
critical radius of the disc (∼ 0.46A, where A is the distance between the centers of stars), the relation of
the masses (q ≤ 0.3), the orbital period Porb, and the disc precession period T = Ppr are as follows:
Ppr =
4
3
Porb(Rext/A)−3/2(q + 1)1/2q−1. (1)
The mass ratio in the β Lyrae system is q ∼= 0.22. The external critical Rex and internal Rin radii of
the disc were obtained from radial velocities of the disc satellite lines, and from the light curve at 6488 Å [1]:
c© M. Skulsky, S. Plachinda, 2004
237
Figure 1. Magnetic field of β Lyrae
Rex
∼= 0.45A and Rinq
∼= 0.295A. The precession periods determined from the formula (1) are then equal to
282.4d and 564.8d, respectively. Thus, the external edge of the accretion disc is rotating round the accretor
during 282.4d. This period is equal to the period of the tidal wave on the surface of donor that is in the resonance
with it. Moreover, the accretion disc is arranged so that his internal edge is turning twice slower and its time
is equal to the fundamental period of Tf = 564.8d. The rotation period of the disc matter on the Keplerian
orbits of the disc’s internal edge is 0.25P (P is the orbital period) at the linear velocity of 266 km s−1, and it is
0.5P on the disc’s external part with the linear velocity of 208 km s−1. It coincides with the observable frames
of the radial velocity of the satellite lines which are formed in the disc. Thus, the matter in the accretion disc
is revolving strictly differentially.
We phased the data of an uniform sample of the Crimean observations with periods of 282d and 338d.
The significant periodicity in both cases is absent as well as the periodicity with the orbital period.
[1] Burnashev V. I., Skulsky M. Yu. H-alpha photometry and magnetic field of β Lyrae // Bull. Crimean Astrophys.
Obs.–1991.–83.–P. 95.
[2] Harmanec P., Morand F., et al. Results of optical interferometry, spectroscopy and photometry // Astron. and
Astrophys.–1996.–312.–P. 879.
[3] Harmanec P., Scholz G. Orbital elements of β Lyrae after the first 100 years of investigation // Astron. and
Astrophys.–1993.–279.–P. 131.
[4] Leone F., Plachinda S. I., Umana G., et al. The magnetic field of the β Lyrae system: Orbital and longer time-scale
variability // Astron. and Astrophys.–2003.–405.–P. 223.
[5] Osaki Y. Irradiation-induced mass-overflow instability as a possible cause of superoutbursts in SU UMa stars //
Astron. and Astrophys.–1985.–144.–P. 369.
[6] Peel M. The 340-d period in β Lyrae // Mon. Notic. Roy. Astron. Soc.–1997.–284.–P. 148.
[7] Plachinda S. Measurements of general magnetic fields on stars with vigorous convective zones using high-accuracy
spectropolarimetry // Photopolarimetry in Remote Sensing / Eds G. Videen, Ya. S. Yatskiv, M. I. Mishchenko.–
Kluwer Acad. Publ., 2004.–P. 351–368.
[8] Skulsky M. Yu. β Lyrae as a magnetic binary star // Pis’ma Astron. Zh.–1982.–8.–P. 238.
[9] Skulsky M. Yu. The magnetic of the Lyrae system // Sov. Astron. Lett.–1985.–11.–P. 21.
[10] Skulsky M. Yu. The magnetic field and tidal resonant phenomena in β Lyrae // Mittelungen KSO Tautenburg.–
1990.–125.–P. 146.
[11] Skulsky M. Yu., Plachinda S. I. A study of the magnetic field of the bright component of β Lyr in the Si II 6347,
6371 lines // Sov. Astron. Lett.–1993.–19.–P. 203.
[12] Van Hamme W., Wilson R. E., Guinan E. F. Periodic Light Changes for β Lyrae // Astron. J.–1995–110.–P. 1350.
238
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| id | nasplib_isofts_kiev_ua-123456789-79649 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0233-7665 |
| language | English |
| last_indexed | 2025-11-27T21:08:47Z |
| publishDate | 2005 |
| publisher | Головна астрономічна обсерваторія НАН України |
| record_format | dspace |
| spelling | Skulsky, M. Plachinda, S. 2015-04-03T17:30:25Z 2015-04-03T17:30:25Z 2005 β Lyrae: on the magnetic field / M. Skulsky, S. Plachinda // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 237-238. — Бібліогр.: 12 назв. — англ. 0233-7665 https://nasplib.isofts.kiev.ua/handle/123456789/79649 β Lyrae shows a complicated and intricate time-dependent behaviour of the magnetic field. en Головна астрономічна обсерваторія НАН України Кинематика и физика небесных тел MS3: Physics of Stars and Galaxies β Lyrae: on the magnetic field Article published earlier |
| spellingShingle | β Lyrae: on the magnetic field Skulsky, M. Plachinda, S. MS3: Physics of Stars and Galaxies |
| title | β Lyrae: on the magnetic field |
| title_full | β Lyrae: on the magnetic field |
| title_fullStr | β Lyrae: on the magnetic field |
| title_full_unstemmed | β Lyrae: on the magnetic field |
| title_short | β Lyrae: on the magnetic field |
| title_sort | β lyrae: on the magnetic field |
| topic | MS3: Physics of Stars and Galaxies |
| topic_facet | MS3: Physics of Stars and Galaxies |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79649 |
| work_keys_str_mv | AT skulskym βlyraeonthemagneticfield AT plachindas βlyraeonthemagneticfield |