On the incidence of weak magnetic fields in DA white dwarfs

@article{Landstreet2012OnTI,
  title={On the incidence of weak magnetic fields in DA white dwarfs},
  author={John D. Landstreet and Stefano Bagnulo and G. Valyavin and Luca Fossati and Stefan Jordan and Dmitry Monin and Gregg A. Wade},
  journal={Astronomy and Astrophysics},
  year={2012},
  volume={545}
}
Context. About 10 % of white dwarfs have magnetic fields with strength i n the range between about 10 5 and 5 10 8 G. It is not known whether the remaining white dwarfs are not magnetic, or if they have magnetic fields too weak to be detected with the techni ques adopted in the large surveys. Information is particularly l acking for the cooler (and generally fainter) white dwarfs. Aims. We describe the results of the first survey specifically devis ed to clarify the detection frequency of kG… 

Figures and Tables from this paper

Magnetic White Dwarfs
In this paper we review the current status of research on the observational and theoretical characteristics of isolated and binary magnetic white dwarfs (MWDs).Magnetic fields of isolated MWDs are
Discovery of an extremely weak magnetic field in the white dwarf LTT 16093 = WD 2047+372
Context. Magnetic fields have been detected in several hundred white dwarfs, with strengths ranging from a few kG to several hundred MG. Only a few of the known fields have a mean magnetic field
A new weak-field magnetic DA white dwarf in the local 20 pc volume
We report the discovery of a new magnetic DA white dwarf (WD), WD 0011 − 721, which is located within the very important 20 pc volume-limited sample of the closest WDs to the Sun. This star has a
A novel and sensitive method for measuring very weak magnetic fields of DA white dwarfs. A search for a magnetic field at the 250 G level in 40 Eridani B
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
Discovery of six new strongly magnetic white dwarfs in the 20 pc local population
The sample of white dwarfs included in the local 20 pc volume documents, fairly accurately, the total production of white dwarfs over roughly 10 Gyr of stellar evolution in this part of the Milky Way
A magnetic white dwarf with five H α components
G183−35 is an unusual white dwarf that shows an H α line split into five components, instead of the usual three components seen in strongly magnetic white dwarfs. Potential explanations for the
Suppression of cooling by strong magnetic fields in white dwarf stars
TLDR
It is found that strong fields are sufficient to suppress convection over the entire surface in cool magnetic white dwarf, which inhibits their cooling evolution relative to weakly magnetic and non-magnetic white dwarfs, making them appear younger than they truly are.
New insight into the magnetism of degenerate stars from the analysis of a volume-limited sample of white dwarfs
Many stars evolve into magnetic white dwarfs (MWDs), and observations may help to understand when the magnetic field appears at the stellar surface, if and how it evolves during the cooling phase,
A fast spinning magnetic white dwarf in the double degenerate, super-Chandrasekhar system NLTT 12758
We present an analysis of the close double degenerate NLTT 12758, which is comprised of a magnetic white dwarf with a field of about 3.1 MG and an apparently non-magnetic white dwarf. We measured an
SDSS J000555.90−100213.5: a hot, magnetic carbon-dominated atmosphere WD rotating with a 2.1 d period
A surprisingly large fraction (70%) of hot, carbon dominated atmosphere (DQ) white dwarfs are magnetic and/or photometrically variable on short timescales up to ~1000 s. However, here we show that
...
...

References

SHOWING 1-10 OF 24 REFERENCES
A search for kilogauss magnetic fields in white dwarfs and hot subdwarf stars
We present new results of a survey for weak magnetic fields among DA white dwarfs, including some brighter hot subdwarf stars. We have detected variable circular polarization in the Hα line of the
Discovery of kilogauss magnetic fields in three DA white dwarfs
We have detected longitudinal magnetic fields between 2 and 4 kG in three (WD 0446−790, WD 1105−048, WD 2359−434) out of a sample of 12 normal DA white dwarfs by using optical spectropolarimetry done
A study of high proper-motion white dwarfs – I. Spectropolarimetry of a cool hydrogen-rich sample†
We conducted a spectropolarimetic survey of 58 high proper-motion white dwarfs which achieved uncertainties of >rsim 2 kG in the Hα line and >rsim 5 kG in the upper Balmer line series. The survey
Spectropolarimetric Survey of Hydrogen‐rich White Dwarf Stars
We have conducted a survey of 61 southern white dwarfs searching for magnetic fields using Zeeman spectropolarimetry. Our objective is to obtain a magnetic field distribution for these objects and,
Analysis of hydrogen-rich magnetic white dwarfs detected in the Sloan Digital Sky Survey
Context A large number of magnetic white dwarfs discovered in the SDSS have so far only been analyzed by visual comparison of the observations with relatively simple models of the radiation
Magnetic fields and rotation of the white dwarfs 40 Eri B and WD 0009+501
We describe the results of our magnetometric monitoring of two white dwarfs: 40 Eri B and WD 0009+501. We found periodic variations in the longitudinal magnetic field of 40 Eri B. The field
SEARCHES FOR MAGNETIC FIELDS IN WHITE DWARFS SINCE BABCOCK
Discoveries of magnetic fields in 26 white dwarfs since 1970 do not negate the basic inference from the work of Babcock - that most of the over 1000 known white dwarfs do not have strong magnetic
The magnetic fields of hot subdwarf stars
Detection of magnetic fields has been reported in several sdO and sdB stars. Recent literature has cast doubts on the reliability of most of these detections. We revisit data previously published in
Magnetic fields at the surfaces of stars
SummaryMagnetic fields have now been detected in stars in several parts of the Hertzsprung-Russell diagram. Roughly dipolar fields ranging in strength between 3× 102 and 3×104 G are found in many
Search for magnetic fields in normal upper--main-sequence stars
A search has been carried out for magnetic fields of the order for 10/sup 2/ gauss in 31 normal O9.5--F6 upper--main-sequence stars and 5 Am stars by measuring the circular polarization of the wings
...
...