Surveying DC White Dwarfs for Magnetic Fields

Putney, A.

doi:10.1086/313037

Cited by 58 publications

(68 citation statements)

References 76 publications

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“…Putney (1997) classified this object as a DC+G/K binary however, in a recent article by Farihi et al (2005) they conclude that this is probably a sdB+G/K binary. This interpretation was developed to make the spectra, color and apparent magnitude compatible, however, it is also consistent with the near zero parallax found in the TOPP.…”

Section: Gj 3667 = Wd 1126+185mentioning

confidence: 96%

Nearby star candidates in the Torino observatory parallax program

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Lattanzi

Jahreiß³

et al. 2007

A&A

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Aims. Candidates with suspect distances from the Catalog of Nearby Stars were included in the Torino Observatory Parallax Program with the goal to clarify their membership in that catalog. Methods. Observations of the objects were made over the period 1996-2001 on the 1.05 m Torino telescope. The trigonometric parallaxes and proper motions were determined using standard techniques. Results. Of the 22 objects examined, 11 are within the 25 pc horizon of the Catalog of Nearby Stars. The remaining objects are either misclassified, sub-dwarfs rather than main sequence dwarfs with consequently overestimated photometric distances, or objects with published trigonometric parallaxes that are incorrect.

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Section: Gj 3667 = Wd 1126+185mentioning

confidence: 96%

Nearby star candidates in the Torino observatory parallax program

Smart

Lattanzi

Jahreiß³

et al. 2007

A&A

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“…Spectropolarimetry of Hα and Hβ Balmer line is commonly applied for detection of strong magnetic fields of white dwarfs (e.g., Schmidt & Smith 1995;Putney 1997). The question was whether we could detect as well much weaker fields, such as those of magnetic Ap stars.…”

Section: Theoretical Basismentioning

confidence: 99%

Measuring magnetic fields of early-type stars with $\vec{FORS{\it 1}}$ at the $\vec{VLT}$

Bagnulo¹,

Szeifert²,

Wade³

et al. 2002

A&A

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Abstract. This paper describes an experiment aimed at evaluating the capability of the FORS1 instrument at the VLT for measuring weak ( 0.1%) Zeeman circular polarization signatures in stellar H Balmer lines. We have obtained low-resolution polarized spectra at 3500-5800Å of two bright A-type stars, HD 94660, and HD 96441. The former is a well known magnetic star, the latter an apparently non-magnetic, unpolarized star that was observed for comparison purposes. In order to test the possibility of performing multi-object spectropolarimetric measurements (e.g., for cluster studies), observations were taken both on-axis (i.e., at the CCD field center) and off-axis (i.e., at the edges of the CCD). In HD 94660 (the magnetic star), we detected a clear signal of circular polarization in all observed hydrogen Balmer lines (i.e., from Hβ to the Balmer limit), with a typical peak-to-peak amplitude of about 0.8%. From the analysis of Stokes V under the weak-field approximation, we have estimated a mean longitudinal field of −2085 ± 85 G, a value fully consistent with previous studies of this star. Notably, we found that at wavelengths shorter than about 4100Å, the polarization signal detected off-axis is about 20-30% smaller than that detected on-axis. No polarization due to the Zeeman effect was detected in the comparison star HD 96441, and we estimate that the contribution due to instrumental circular polarization is limited to the order of 0.01%. This experiment demonstrates the effectiveness of FORS1 at the VLT as a tool for high-sensitivity diagnosis of the magnetic field in upper main sequence stars, providing the potential for measuring fields in fainter and more rapidly rotating stars than has previously been possible.

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“…References -(1a) Marsh et al (1997a); (1b) Marsh et al (1997b); (2) ; (3) Finley et al (1997); (4) Vennes (1999); (5) ; (6) Bergeron et al (2001); (7) Bergeron et al (1992); (8) Reid (1996); (9) Claver et al (2001); (10) Bergeron et al (1995b); (11) Bergeron et al (1995a); (12) Napiwotzki et al (1999); (13) Bragaglia et al (1995); (14) Homeier et al (1998); (15) Provencal et al (1998); (16) Heber et al (1997); (17) Wickramasinghe & Ferrario (2000); (18) Schmidt et al (1992); (19) Wegner et al (1989); (20) Putney (1997); (21) Bergeron et al (1994); (22) Barstow et al (1995); (23) Burleigh et al (1999); (24) Ferrario et al (1997); (25) ; (26) Holberg et al (1998); (27) Burleigh (1999); (28) …”

Section: The Tail Of the Massive Wd Distributionunclassified

A catalogue of isolated massive white dwarfs

Nalezyty

Madej

2004

A&A

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Abstract. We present in this paper a catalogue of 112 massive isolated white dwarfs, with masses M > 0.8 M . Mass determinations and other parameters of white dwarfs were compiled from the available literature. For each star we present averaged values of mass, effective temperature, logarithm of surface gravity log g, radius, distance, and the surface magnetic field for magnetic white dwarfs. The mass distribution of our sample is a slowly decreasing continuum function for masses larger than 0.9 M , with an overlapping secondary maximum at 1.04 M . We conclude that the mass distribution of known massive magnetic white dwarfs is flat, whereas nonmagnetic WDs exhibit a steeper mass distribution towards the highest masses. The secondary maximum at 1.04 M is caused exclusively by nonmagnetic white dwarfs. We note that the 4 most massive stars with masses M ≥ 1.3 M are magnetic white dwarfs. Our results show also, that the occurrence of magnetism in massive white dwarfs does not depend on the cooling age (above T eff = 5000 K).

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Surveying DC White Dwarfs for Magnetic Fields

Cited by 58 publications

References 76 publications

Nearby star candidates in the Torino observatory parallax program

Nearby star candidates in the Torino observatory parallax program

Measuring magnetic fields of early-type stars with $\vec{FORS{\it 1}}$ at the $\vec{VLT}$

A catalogue of isolated massive white dwarfs

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