2001A&A...367..577F


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.13CET12:03:31

2001A&A...367..577F - Astronomy and Astrophysics, volume 367, 577-581 (2001/2-4)

Search for indications of fast rotation in the linear polarization of the magnetic white dwarf Grw+70deg8247.

FRIEDRICH S. and JORDAN S.

Abstract (from CDS):

objS{AC +70 8247}{Grw+70°8247} belongs to a small group of magnetic white dwarfs which despite repeated observations did not show any changes in their polarization over decades. The inferred rotation periods are of the order of hundred years which is not easy to understand if angular momentum is conserved during stellar evolution. An alternative possibility, which was to our knowledge never investigated, might be fast rotation with a period between some minutes and a couple of seconds. Assuming a mass of 1 M and a radius of 1/100 R the shortest possible period is about 10 s. In order to test this hypothesis the linear polarization of Grw+70°8247 was measured at the 2.2 m telescope at the Calar Alto Observatory, Spain, with a time resolution of 3 s by trailing the linear polarized image of Grw+70°8247 over the CCD chip. The linear polarization was searched for periodicities in the range between 10 s and 4000 s. Investigations with synthetic polarized data using the same window function and an assumed sinusoidal variation showed that variations with amplitudes of 40% relative to the amount of average linear polarization should be detectable. However, no periodicities at this or higher levels of significance were found. This would be in accordance with a recent report on slow rotation of GD 229 and G 240-72, but fast variations with lower amplitudes could not be ruled out.

Abstract Copyright:

Journal keyword(s): stars: individual: Grw+70°8247 - stars: rotation - stars: white dwarfs

CDS comments: Fig. 1 + text : comparison * A and B not in SIMBAD

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 HD 11831 * 01 58 03.8143291370 +60 23 27.932463527 9.29 8.84 8.12     A2Iab 31 0
2 V* CL Oct WD* 03 17 15.8451763319 -85 32 25.561178526   13.78 13.66 15.19   DAP 135 1
3 LB 9802 WD* 03 17 19.1281232921 -85 32 31.288417104   13.78 13.66 14.43   DA 123 1
4 EGGR 372 WD* 17 48 07.9929730558 +70 52 35.921195401   14.55   13.5   DQ9P 122 0
5 LAWD 73 WD* 19 00 10.2534325163 +70 39 51.418372586   13.24   13.5   DAP4.5 216 0
6 GD 229 WD* 20 12 22.2671811253 +31 13 48.884997524 13.62 14.77 14.85     DXP2 116 0

    Equat.    Gal    SGal    Ecl

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2019.11.13-12:03:31

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