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Magnetism, X-rays a...
Magnetism, X-rays and accretion rates in WD 1145+017 and other polluted white dwarf systems
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- Farihi, J. (författare)
- UCL, Dept Phys & Astron, London WC1E 6BT, England.
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- Fossati, L. (författare)
- Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria.
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- Wheatley, P. J. (författare)
- Univ Warwick, Dept Phys, Coventry CV4 7AL, W Midlands, England.
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- Metzger, B. D. (författare)
- Columbia Univ, Dept Phys, 538 W 120th St, New York, NY 10027 USA.
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- Mauerhan, J. (författare)
- Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, CA 94720 USA.
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- Bachman, S. (författare)
- Indiana Univ Penn, Dept Phys, Indiana, PA 15705 USA.;Wesleyan Univ, Astron Dept, Middletown, CT 06459 USA.;Wesleyan Univ, Van Vleck Observ, Middletown, CT 06459 USA.
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- Gänsicke, B. T. (författare)
- Univ Warwick, Dept Phys, Coventry CV4 7AL, W Midlands, England.
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- Redfield, S. (författare)
- Wesleyan Univ, Astron Dept, Middletown, CT 06459 USA.;Wesleyan Univ, Van Vleck Observ, Middletown, CT 06459 USA.
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- Cauley, P. W. (författare)
- Wesleyan Univ, Astron Dept, Middletown, CT 06459 USA.;Wesleyan Univ, Van Vleck Observ, Middletown, CT 06459 USA.
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- Kochukhov, Oleg (författare)
- Uppsala universitet,Observationell astrofysik
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- Achilleos, N. (författare)
- UCL, Dept Phys & Astron, London WC1E 6BT, England.
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- Stone, N. (författare)
- Columbia Univ, Dept Astron, New York, NY 10027 USA.
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UCL, Dept Phys & Astron, London WC1E 6BT, England Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria. (creator_code:org_t)
- 2017-10-24
- 2018
- Engelska.
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 474:1, s. 947-960
- Relaterad länk:
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https://academic.oup...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- This paper reports circular spectropolarimetry and X-ray observations of several polluted white dwarfs including WD 1145+017, with the aim to constrain the behaviour of disc material and instantaneous accretion rates in these evolved planetary systems. Two stars with previously observed Zeeman splitting, WD 0322-019 and WD 2105-820, are detected above 5 sigma and < B-z > > 1 kG, while WD 1145+017, WD 1929+011, and WD 2326+049 yield (null) detections below this minimum level of confidence. For these latter three stars, high-resolution spectra and atmospheric modelling are used to obtain limits on magnetic field strengths via the absence of Zeeman splitting, finding B-* < 20 kG based on data with resolving power R approximate to 40 000. An analytical framework is presented for bulk Earth composition material falling on to the magnetic polar regions of white dwarfs, where X-rays and cyclotron radiation may contribute to accretion luminosity. This analysis is applied to X-ray data for WD 1145+017, WD 1729+371, and WD 2326+049, and the upper bound count rates are modelled with spectra for a range of plasma kT = 1-10 keV in both the magnetic and non-magnetic accretion regimes. The results for all three stars are consistent with a typical dusty white dwarf in a steady state at 108-109 g s(-1). In particular, the non-magnetic limits for WD 1145+017 are found to be well below previous estimates of up to 10(12) g s(-1), and likely below 1010 g s(-1), thus suggesting the star-disc system may be average in its evolutionary state, and only special in viewing geometry.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- circumstellar matter
- stars: magnetic field
- planetary systems
- white dwarfs
- X-rays: stars
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Farihi, J.
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Fossati, L.
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Wheatley, P. J.
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Metzger, B. D.
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Mauerhan, J.
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Bachman, S.
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visa fler...
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Gänsicke, B. T.
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Redfield, S.
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Cauley, P. W.
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Kochukhov, Oleg
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Achilleos, N.
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Stone, N.
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visa färre...
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