New magnetic chemically peculiar stars

Kudryavtsev, D. O.; Romanyuk, I. I.; Elkin, V. G.; Paunzen, E.

doi:10.1111/j.1365-2966.2006.10994.x

Cited by 89 publications

(90 citation statements)

References 55 publications

(123 reference statements)

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“…Bagnulo et al (2006) and Kudryavtsev et al (2006) independently discovered a magnetic field in this star. HD 45583 is classified as a variable of the α 2 CVn type.…”

Section: Also Foundmentioning

confidence: 99%

“…Glagolevskij (1994) obtained T eff = 12 800 and 12 400 K from Q and X indices, respectively. Kudryavtsev et al (2006) discovered a magnetic field. We derive a low rotation velocity.…”

Section: Also Foundmentioning

confidence: 99%

“…HD 49713 was classified as peculiar by Walther (1949) on the basis of spectroscopic observations and was classified as a variable chemically peculiar star of the α 2 CVn type by Kazarovets (1999). Kudryavtsev et al (2006) discovered a magnetic field. We present the first determination of the atmospheric parameters and detailed chemical composition of this star.…”

Section: Also Foundmentioning

confidence: 99%

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Abundance analysis of prime B-type targets for asteroseismology

Niemczura¹,

Morel²,

Aerts

2009

A&A

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Aims. The main goal of the ground-based seismology support program for the CoRoT mission was to obtain photometric and spectroscopic data for stars in the fields monitored by the satellite. These ground-based observations were collected in the GAUDI archive. High-resolution spectra of more than 200 B-type stars are available in this database, and about 45% of them is analysed here. Methods. To derive the effective temperature of the stars, we used photometric indices. Surface gravities were obtained by comparing observed and theoretical Balmer line profiles. To determine the chemical abundances and rotational velocities, we used a spectrum synthesis method, which consisted of comparing the observed spectrum with theoretical ones based on the assumption of LTE. Results. Atmospheric parameters, chemical abundances, and rotational velocities were determined for 89 late-B stars. The dominant species in their spectra are iron-peak elements. The average Fe abundance is 7.24 ± 0.45 dex. The average rotational velocity is 126 km s −1 , but there are 13 and 20 stars with low and moderate V sin i values, respectively. The analysis of this sample of 89 late B-type stars reveals many chemically peculiar (CP) stars. Some of them were previously known, but at least 9 new CP candidates, among which at least two HgMn stars, are identified in our study. These CP stars as a group exhibit V sin i values lower than the stars with normal surface chemical composition.

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“…Bagnulo et al (2006) and Kudryavtsev et al (2006) independently discovered a magnetic field in this star. HD 45583 is classified as a variable of the α 2 CVn type.…”

Section: Also Foundmentioning

confidence: 99%

“…Glagolevskij (1994) obtained T eff = 12 800 and 12 400 K from Q and X indices, respectively. Kudryavtsev et al (2006) discovered a magnetic field. We derive a low rotation velocity.…”

Section: Also Foundmentioning

confidence: 99%

Section: Also Foundmentioning

confidence: 99%

See 1 more Smart Citation

Abundance analysis of prime B-type targets for asteroseismology

Niemczura¹,

Morel²,

Aerts

2009

A&A

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“…We used both of the regimes in observations of 40 Eri B. In contrast to the previous observations of this white dwarf with this instrument , the image slicer now employed provides the MSS with much higher stability, which makes it possible to carry out measurement of stellar longitudinal fields with uncertainties as low as 30 G (Kudryavtsev et al 2006). …”

Section: Field Measurements With the Sao Main Stellar Spectrographmentioning

confidence: 99%

“…The analyser has a rotatable quarter-wave plate that is able to take two fixed positions corresponding to the angles −45 deg and +45 deg relative to the principal axes of the birefringent crystal. More details about the instrument and observational technique can be found in Joshi et al (2012) and Kudryavtsev et al (2006). The MSS spectropolarimeter exploits two regimes of spectral resolution: R = 15 000 and R = 6000.…”

Section: Field Measurements With the Sao Main Stellar Spectrographmentioning

confidence: 99%

A novel and sensitive method for measuring very weak magnetic fields of DA white dwarfs

Landstreet

Bagnulo

Valyavin

et al. 2015

A&A

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Context. Searches for magnetic fields in white dwarfs have clarified both the frequency of occurrence and the global structure of the fields found down to field strengths of the order of 500 kG. Below this level, the situation is still very unclear. Aims. We are engaged in a project to find and study the weakest magnetic fields that are detectable in white dwarfs, in order to empirically determine how the frequency of occurrence and the structure of fields present changes with field strength. In this paper we report the successful testing of a very sensitive method of longitudinal field detection in DA white dwarfs. We use this method to carry out an extremely sensitive search for magnetism in the bright white dwarf 40 Eri B. Methods. The method of field measurement we use is to measure, at high spectral resolution, the polarisation signal V/I of the narrow non-LTE line core in Hα in DA stars. This small feature provides a much higher amplitude polarisation signal than the broad Balmer line wings. We test the usefulness of this technique by searching for a weak magnetic field in 40 Eri B. Results. One hour of observation of I and V Stokes components of the white dwarf 40 Eri B using ESPaDOnS at the CFHT is found to provide a standard error of measurement of the mean longitudinal magnetic field B z of about 85 G. This is the smallest standard error of field measurement ever obtained for a white dwarf. The non-detections obtained are generally consistent with slightly less accurate measurements of 40 Eri B obtained with ISIS at the WHT and the Main Stellar Spectrograph at SAO, in order to provide comparison standards for the new method. These further measurements allow us to make a quantitative comparison of the relative efficiencies of low-resolution spectropolarimetery (using most or all of the Balmer lines) with the new method (using only the core of Hα). Conclusions. The new method of field detection reaches the level of sensitivity that was expected. It appears that for suitable DA stars, about the same field uncertainties can be reached with ESPaDOnS on the CFHT, in a given integration time, as with FORS on an 8-m telescope, and uncertainties are a factor of two better than with low-resolution spectropolarimetry with other 4-6-m class telescopes. However, even with this extraordinary sensitivity, there is no clear indication of the presence of any magnetic field in 40 Eri B above the level of about 250 G.

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The science case of the PEPSI high‐resolution echelle spectrograph and polarimeter for the LBT

Strassméier¹,

Pallavicini²,

Rice³

et al. 2004

Astron Nachr

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Abstract. We lay out the scientific rationale for and present the instrumental requirements of a high-resolution adaptiveoptics Echelle spectrograph with two full-Stokes polarimeters for the Large Binocular Telescope (LBT) in Arizona. Magnetic processes just like those seen on the Sun and in the space environment of the Earth are now well recognized in many astrophysical areas. The application to other stars opened up a new field of research that became widely known as the solarstellar connection. Late-type stars with convective envelopes are all affected by magnetic processes which give rise to a rich variety of phenomena on their surface and are largely responsible for the heating of their outer atmospheres. Magnetic fields are likely to play a crucial role in the accretion process of T-Tauri stars as well as in the acceleration and collimation of jet-like flows in young stellar objects (YSOs). Another area is the physics of active galactic nucleii (AGNs) , where the magnetic activity of the accreting black hole is now believed to be responsible for most of the behavior of these objects, including their X-ray spectrum, their notoriously dramatic variability, and the powerful relativistic jets they produce. Another is the physics of the central engines of cosmic gamma-ray bursts, the most powerful explosions in the universe, for which the extreme apparent energy release are explained through the collimation of the released energy by magnetic fields. Virtually all the physics of magnetic fields exploited in astrophysics is somehow linked to our understanding of the Sun's and the star's magnetic fields.

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New magnetic chemically peculiar stars

Cited by 89 publications

References 55 publications

Abundance analysis of prime B-type targets for asteroseismology

Abundance analysis of prime B-type targets for asteroseismology

A novel and sensitive method for measuring very weak magnetic fields of DA white dwarfs

The science case of the PEPSI high‐resolution echelle spectrograph and polarimeter for the LBT

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