Precise Spectropolarimetric Measurements of Magnetic Fields on Some Solar‐like Stars

Plachinda, S. I.; Тарасова, Т. Н.

doi:10.1086/306912

Cited by 35 publications

(32 citation statements)

References 21 publications

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“…Our corresponding longitudinal field measurement of 2 ± 5 G has one of the lowest errors in our survey, but it is not a large improvement over other measurements for this well-studied star. Landstreet (1982), using a coudé line profile scanner with polarization module, reported two non-detections with σ = 7 G. Borra et al (1984) made a longitudinal field measurement using circular spectropolarimetry of many lines simultaneously, in a technique resembling LSD, and found B l = −7.5 ± 5.9 G. Bedford et al (1995), using a magnetooptical-filter spectrometer, made 12 measurements resulting in null detections with σ = 0.7-1.8 G. Plachinda & Tarasova (1999) used a coudé spectropolarimeter along with their "Flip-Flop Zeeman Measurement" technique and measured the longitudinal field of HD 61421 to be B l = −1.34 ± 1.0 G.…”

Section: Hd 61421 (Procyon)mentioning

confidence: 99%

A highly sensitive search for magnetic fields in B, A and F stars

Shorlin

Wade

Donati

et al. 2002

A&A

155

197

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Abstract. Circular spectropolarimetric observations of 74 stars were obtained in an attempt to detect magnetic fields via the longitudinal Zeeman effect in their spectral lines. The sample observed includes 22 normal B, A and F stars, four emission-line B and A stars, 25 Am stars, 10 HgMn stars, two λ Boo stars and 11 magnetic Ap stars. Using the Least-Squares Deconvolution multi-line analysis approach , high precision Stokes I and V mean signatures were extracted from each spectrum. We find absolutely no evidence for magnetic fields in the normal, Am and HgMn stars, with upper limits on longitudinal field measurements usually considerably smaller than any previously obtained for these objects. We conclude that if any magnetic fields exist in the photospheres of these stars, these fields are not ordered as in the magnetic Ap stars, nor do they resemble the fields of active late-type stars. We also detect for the first time a field in the A2pSr star HD 108945 and make new precise measurements of longitudinal fields in five previously known magnetic Ap stars, but do not detect fields in five other stars classified as Ap SrCrEu. We also report new results for several binary systems, including a new v sin i for the rapidly rotating secondary of the Am-δ Del SB2 HD 110951.

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Section: Hd 61421 (Procyon)mentioning

confidence: 99%

A highly sensitive search for magnetic fields in B, A and F stars

Shorlin

Wade

Donati

et al. 2002

A&A

155

197

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“…Left and right circularly polarized spectra were acquired with the Stokesmeter, similar to the one described by Plachinda & Tarasova (1999). It consists of an achromatic (4000-6800Å) rotateable quarter-wave plate, a beam splitter, made of a calcite plate, and a fixed achromatic quarter-wave plate on exit which converts the linearly polarized light into circularly polarized light to avoid linear polarized light attenuation on theéchelle.…”

Section: High-resolution Stokes I and V Spectramentioning

confidence: 99%

Doppler Imaging of stellar magnetic fields

Kochukhov¹,

Piskunov²,

Ilyin

et al. 2002

A&A

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Abstract. We used the new magnetic Doppler Imaging code to reconstruct the magnetic field geometry and surface abundance distributions for the classical magnetic CP star α 2 CVn. High-resolution spectropolarimetric observations in the Stokes I and V parameters were collected with the SOFINéchelle spectrograph at the Nordic Optical Telescope. This superb observational material in combination with the advanced modelling technique allowed to achieve the first simultaneous self-consistent mapping of the vector magnetic field and the abundance distributions of six chemical elements. In recovering the stellar magnetic distribution no prior assumptions about the field geometry or strength were made. Instead, we restricted possible solutions of the inverse problem by means of the multipolar regularization method which searches for the field map close to a general non-axisymmetric multipolar configuration but allows departures from this geometry if that is required by the observational data. We found that the magnetic field of α 2 CVn is dominated by a dipolar component and has a minor quadrupole contribution. The surface distributions of the chemical species form symmetric patterns which closely follow the magnetic geometry. This discovery constitutes one of the first direct observational constraints on the horizontal diffusion processes acting in the upper envelope of a strongly magnetized stellar atmosphere. In addition to the extensive magnetic Doppler Imaging analysis, we derived new accurate estimates of the atmospheric parameters and basic physical properties of α 2 CVn using the energy distribution, hydrogen line profiles and the recent Hipparchos parallax.

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“…To demonstrate that we have no systematic instrumental shift, we reproduce here the results of our investigations of stability of the instrumental zero point over the long time interval from 1989 to 2002. The systematic instrumental shift determined using 27 observational nights during 1989-1997 is equal to B e = −0.12 ± 0.99 G (Plachinda & Tarasova 1999). In addition in this paper, we determined the systematic instrumental shift using N = 1491 highaccuracy measurements of the magnetic field of four cool supergiants (Plachinda 2005 B e = −0.44 ± 0.38 G. Thus, we conclude that long-term systematic effects are absent within the observational error <1 G.…”

Section: Observations and Data Reductionmentioning

confidence: 63%

“…Signal-to-noise ratios of a single spectrum were typically 350-600 with spectral resolving power of 2.2 × 10 4 . The study of the magnetic field of the star was carried out with the same equipment and "Flip-Flop" procedure that have already been discussed in detail by Plachinda & Tarasova (1999), Plachinda (2004), and Plachinda (2005). We carried out the sequence of individual subexposures on the stellar object with the entrance achromatic quarter-wave plate rotated by ±90…”

Section: Observations and Data Reductionmentioning

confidence: 99%

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A study of the β Cephei star γ Pegasi: binarity, magnetic field, rotation, and pulsations

Butkovskaya¹,

Plachinda

2007

A&A

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Aims. We provide observational material to study the magnetic field variability of the classical β Cep-type star γ Peg. Methods.The observations were carried out in the He i 6678 line in the course of 23 observing nights from 1997 to 2005 with using the Coudé spectrograph in spectropolarimetric mode at the Crimean 2.6 m telescope. The behavior of stellar wind was studied in the UV region using data from the IUE satellite (the INES database). Results. It is shown that the UV stellar wind exhibits a variability. A variation of the wind due to stellar pulsations has been detected.In the He i 6678 line, the abnormally blueshifted radial velocities (γ = −60.57 ± 0.29 km s −1 ) were detected during a single night in 2005. We do not confirm the 370.5-day orbital period. The most probable orbital period was estimated as P orb = 6.81608±0.00012 day. The ratio P orb /P puls = 44.92 appeared to be very close to integer. We have detected the presence of a weak magnetic field on the star. The longitudinal component of the field varies from -10 G to 30 G with the stellar rotation. The most probable rotational period is P rot = 6.6538 ± 0.0016 days. Both the orbital and the rotational periods are integral multiples of the difference between them: P orb /|P orb − P rot | = 42.002, and P rot /|P orb − P rot | = 41.002. Variation in the longitudinal magnetic field during the pulsation period with an amplitude about 7 G was detected.Key words. stars: magnetic fields -stars: early-type -stars: oscillations -stars: binaries: spectroscopic -stars: individual: γ Pegasi IntroductionThe classical β Cep-type star γ Peg (HD 886, HR 39, Sp B2 IV) exhibits low-order purely radial pulsations. It has one of the weakest amplitude variations in radial velocity 2K = 7 km s −1 , light ∆m v = 0.017 with short pulsation period of 0.15 day, and de Jager et al. (1982) concluded that γ Peg has a virtually zero rotational velocity component; i.e., the star is seen rotation pole-on. pointed out a possibility that the γ-axis of the 0.15-day velocity curve of γ Peg varies. Harmanec et al. (1979) determined the 6.83-day period for the variations in the γ-axis and concluded that the star is a spectroscopic binary with a circular, slightly inclined orbit. Ducatel et al. (1981) also detected the day-to-day variations of the γ-axis, but they suggest that these variations are associated with stellar oscillations.According to analysis of high-resolution observations of this star that were carried out in a period from 1997 to 2005, Butkovskaya et al. (2006 concluded that γ Peg is a spectroscopic binary as suggested by Harmanec et al. (1979). Recently, Chapellier et al. (2006), combining their radial velocity measurements with data from the literature, confirmed the binarity of this star but with another orbital period of 370.5 days.The first attempt to detect a magnetic field on γ Peg was made by Babcock (1958). He found no evidence of a magnetic field in this sharp-line star. Rudy & Kemp (1978) measured theThe radial velocity data are only availabl...

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Precise Spectropolarimetric Measurements of Magnetic Fields on Some Solar‐like Stars

Abstract: Results of precision measurements of the net longitudinal component of magnetic Ðeld strength (B e ) performed for Procyon (a CMi, F5 IVÈV) and three solar-type starsÈb Com

Cited by 35 publications

References 21 publications

A highly sensitive search for magnetic fields in B, A and F stars

A highly sensitive search for magnetic fields in B, A and F stars

Doppler Imaging of stellar magnetic fields

A study of the β Cephei star γ Pegasi: binarity, magnetic field, rotation, and pulsations

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