2007A&A...462.1097J -
Astronomy and Astrophysics, volume 462, 1097-1101 (2007/2-2)
The fraction of DA white dwarfs with kilo-Gauss. magnetic fields.
JORDAN S., AZNAR CUADRADO R., NAPIWOTZKI R., SCHMID H.M. and SOLANKI S.K.
Abstract (from CDS):
Weak magnetic fields have been searched for on only a small number of white dwarfs. Current estimates find that about 10% of all white dwarfs have fields in excess of 1MG; according to previous studies this number increases up to about 25% in the kG regime. Our aim is to improve on these statistics by a new sample of ten white dwarfs in order to determine the ratio of magnetic to field-free white dwarfs. Mean longitudinal magnetic fields strengths were determined by means of high-precision circular polarimetry of Hβ and Hγ with the FORS1 spectrograph of the VLT ``Kueyen'' 8m telescope. In one of our objects (LTT7987), we detected a statistically significant (97% confidence level) longitudinal magnetic field varying between (-1±0.5)kG and (+1±0.5)kG. This would be the weakest magnetic field ever found in a white dwarf, but systematic errors cannot completely be ruled out at this level of accuracy. We also observed the sdO star EC11481-2303 but could not detect a magnetic field. VLT observations with uncertainties typically of 1000G or less suggest that 15-20% of WDs have kG fields. Together with previous investigations, the fraction of kG magnetic fields in white dwarfs amounts to about 11-15%, which is close to the current estimations for highly magnetic white dwarfs (>1MG).
Abstract Copyright:
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Journal keyword(s):
stars: white dwarfs - stars: magnetic fields
CDS comments:
Paragraph 4. L 362-434 is a misprint for L 362-81
Simbad objects:
17
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