Dynamical determination of the quadrupole mass moment of a white dwarf |
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| Authors: | Lorenzo Iorio |
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| Institution: | (1) Viale Unità di Italia 68, 70125 Bari, Italy |
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| Abstract: | In this paper we dynamically determine the quadrupole mass moment Q of the magnetic white dwarf WD 0137-349 by looking for deviations from the third Kepler law induced by Q in the orbital period of the recently discovered brown dwarf moving around it in a close 2-hr orbit. It turns out that a
purely Newtonian model for the orbit of WD 0137-349B, assumed circular and equatorial, is adequate, given the present-day
accuracy in knowing the orbital parameters of such a binary system. Our result is Q=(−1.5±0.9)×1047 kg m2 for i=35 deg. It is able to accommodate the 3-sigma significant discrepancy of (1.0±0.3)×10−8 s−2 between the inverse square of the phenomenologically determined orbital period and the inverse square of the calculated Keplerian
one. The impact of i, for which an interval Δ
i of possible values close to 35 deg is considered, is investigated as well. |
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| Keywords: | Binaries: close Stars: individual BPS CS 29504-0036 Stars: brown dwarfs |
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