Spectral Disentangling Applied to Triple Systems: RV Crt

Hensberge, H.; Vaz, L. P. R.; Torres, K. B. V.; Armond, Tina

doi:10.1007/978-3-540-74745-1_7

Cited by 4 publications

(4 citation statements)

References 2 publications

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“…SB2 systems with a magnetic Ap star are very rare and HD 135728AB may be particularly promising for illuminating the magnetic field origin question. Examples of other such cases are: HD 59435 (Wade, Mathys, & North 1999), HD 55719 (Bonsack 1976) and HD 98088 (Abt et al 1968;Hensberge 1974;Bychkov, Bychkova, & Madej 2005). These binaries have the following characteristics: magnetic periods of 5.8 -1360 d, orbital periods of 5.9 -1386.1 d, magnetic fields of 1.45 -8 kG and companion-to-Ap star mass ratios of 0.75 -1.33.…”

Section: Discussionmentioning

confidence: 99%

Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines^★

Freyhammer

Elkin

Kurtz

et al. 2008

Monthly Notices of the Royal Astronomical Society

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Chemically peculiar A stars (Ap) are extreme examples of the interaction of atomic element diffusion processes with magnetic fields in stellar atmospheres. The rapidly oscillating Ap stars provide a means for studying these processes in three dimensions and are at the same time important for studying the pulsation excitation mechanism in A stars. As part of the first comprehensive, uniform, high‐resolution spectroscopic survey of Ap stars, which we are conducting in the Southern hemisphere with the Michigan Spectral Catalogues as the basis of target selection, we report here the discovery of 17 new magnetic Ap stars having spectroscopically resolved Zeeman components from which we derive magnetic field moduli in the range 3–30 kG. Among these are (1) the current second strongest known magnetic A star, (2) a double‐lined Ap binary with a magnetic component and (3) an A star with particularly peculiar and variable abundances. Polarimetry of these stars is needed to constrain their field geometries and to determine their rotation periods. We have also obtained an additional measurement of the magnetic field of the Ap star HD 92499.

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Section: Discussionmentioning

confidence: 99%

Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines^★

Freyhammer

Elkin

Kurtz

et al. 2008

Monthly Notices of the Royal Astronomical Society

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“…Therefore, the direct CCD exposures at different exposure levels (mentioned above) were used to construct a two-dimensional differential response map of the CCD (the response-frame). It exhibits structures related to the manufacturing process of the chip (small dark spots with up to 8% light loss; bright arcs with up to 3% increased brightness presumably caused by unequal coating; a periodic row pattern with amplitude <1% presumably reflecting variations in pixel surface) and less important pixel-to-pixel variations of < 0.3% rms (Hensberge et al 1993). The rms of the random noise on this frame is 0.15%.…”

Section: Ccd Calibrationmentioning

confidence: 90%

“…From tests performed with direct illumination of the CCD by green LEDs with integration times ranging from 1 to 800 sec, we conclude that more than 99.5% of the pixels give a linear response to better than 1:250 over a very large intensity range (see Hensberge et al 1993 for a description of the tests and the applied methods of analysis). The constraint on linearity we find is stronger than claimed by ESO (Abbott and Sinclaire 1993).…”

Section: Ccd Calibrationmentioning

confidence: 97%

High S/N Echelle Spectroscopy in Young Stellar Groups. I. Observations and Data Reduction

Verschueren

Hensberge²,

David³

et al. 1997

PASP

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ABSTRACT. This is the first paper in a series in which we study the kinematical structure and dynamical evolution of OB associations and young stellar clusters. By means of high-resolution high-signal-to-noise (S/N) spectroscopic observations, our goal is to obtain accurate stellar radial and rotational velocities and information on binarity in a selected number of such systems. In the present paper, we discuss the observations and data reduction for a sample of 156 early-type, established or probable, members of the Sco OB2 association. These stars form a subset of a larger sample that was observed by the HIPPARCOS satellite. The observations presented here were performed at the ESO 1.5-m telescope using the ECHELEC echelle CCD spectrograph. The formal S/N obtained is typically 70 at 3800 Â and 300 at 4050 Â. A new data-reduction package was developed. For the sake of quality control over the final spectra, we critically evaluated the performance of each procedure in the reduction. Emphasis is on techniques for detecting systematic errors in an empirical way and for maximally eliminating them, at least on a differential level. The accuracy of our reduced spectra is limited by intrinsic instrumental imperfections. Local random errors are given and the amplitude of systematic residuals that (may) occur in certain spectral regions is estimated in considerable detail. In anticipation of subsequent papers in this series, we finally show that the accuracy of differential radial velocities (for spectra of the same star) is essentially limited by centering and zero-point uncertainties amounting to ^ 1 km s -1 (rms).

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“…In other words, the dedicated investigation of the longest variation periods of Ap stars started less than 50 years ago. Highlights of the first two decades of this effort include the works of Wolff (1975), Hensberge et al (1984), and Rice (1988). However, the overall picture remained patchy.…”

Section: Introductionmentioning

confidence: 99%

Variation of the magnetic field of the Ap star HD 50169 over its 29-year rotation period

Mathys

Romanyuk

Hubrig

et al. 2019

A&A

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Context. The Ap stars that rotate extremely slowly, with periods of decades to centuries, represent one of the keys to the understanding of the processes leading to the differentiation of stellar rotation. Aims. We characterise the variations of the magnetic field of the Ap star HD 50169 and derive constraints about its structure. Methods. We combine published measurements of the mean longitudinal field B z of HD 50169 with new determinations of this field moment from circular spectropolarimetry obtained at the 6-m telescope BTA of the Special Astrophysical Observatory of the Russian Academy of Sciences. For the mean magnetic field modulus B , literature data are complemented by the analysis of ESO spectra, both newly acquired and from the archive. Radial velocities are also obtained from these spectra. Results. We present the first determination of the rotation period of HD 50169, P rot = 29.04 ± 0.82 y. HD 50169 is currently the longest-period Ap star for which magnetic field measurements have been obtained over more than a full cycle. The variation curves of both B z and B have a significant degree of anharmonicity, and there is a definite phase shift between their respective extrema. We confirm that HD 50169 is a wide spectroscopic binary, refine its orbital elements, and suggest that the secondary is probably a dwarf star of spectral type M. Conclusions. The shapes and mutual phase shifts of the derived magnetic variation curves unquestionably indicate that the magnetic field of HD 50169 is not symmetric about an axis passing through its centre. Overall, HD 50169 appears similar to the bulk of the long-period Ap stars.

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Spectral Disentangling Applied to Triple Systems: RV Crt

Cited by 4 publications

References 2 publications

Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines^★

Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines^★

High S/N Echelle Spectroscopy in Young Stellar Groups. I. Observations and Data Reduction

Variation of the magnetic field of the Ap star HD 50169 over its 29-year rotation period

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Spectral Disentangling Applied to Triple Systems: RV Crt

Cited by 4 publications

References 2 publications

Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines★

Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines★

High S/N Echelle Spectroscopy in Young Stellar Groups. I. Observations and Data Reduction

Variation of the magnetic field of the Ap star HD 50169 over its 29-year rotation period

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Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines^★

Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines^★