Variations in D/H and D/O from New<i>Far Ultraviolet Spectroscopic Explorer</i>Observations

Oliveira, Cristina; Moos, H. W.; Chayer, P.; Kruk, J. W.

doi:10.1086/500962

Cited by 25 publications

(37 citation statements)

References 70 publications

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“…Interstellar absorption for 1145+017 was assumed to have N H = 10 20 cm −2 , which is consistent with the observed hydrogen column density to WD 1034+001 (Oliveira et al 2006), a star in the same direction at a comparable distance. This adopted value is also consistent with the survey of hydrogen column densities by Linsky et al (2006), where practically all objects within 100 pc of the Sun have N H 10 19 cm −2 , and all objects within 200 pc have N H 10 20 cm −2 .…”

Section: X-rayssupporting

confidence: 58%

Magnetism, X-rays and accretion rates in WD 1145+017 and other polluted white dwarf systems

Farihi

Fossati

Wheatley

et al. 2017

Monthly Notices of the Royal Astronomical Society

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This paper reports circular spectropolarimetry and X-ray observations of several polluted white dwarfs including WD 1145+017, with the aim to constrain the behavior of disk 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 5σ 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 modeling 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 ≈ 40 000. An analytical framework is presented for bulk Earth composition material falling onto 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 modeled 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 10 8 − 10 9 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 , thus suggesting the star-disk system may be average in its evolutionary state, and only special in viewing geometry.

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Section: X-rayssupporting

confidence: 58%

Magnetism, X-rays and accretion rates in WD 1145+017 and other polluted white dwarf systems

Farihi

Fossati

Wheatley

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…In addition to the dependences on α discussed by other authors, we also included the dependence of the light nuclei masses on α (Landau et al 2006). The code was also updated with the reaction rates reported by Bergström et al (1999 Kirkman et al (2003), Burles & Tytler (1998a), Burles & Tytler (1998b), Crighton et al (2004), O'Meara et al (2006), and Oliveira et al (2006). For 7 Li we considered the results from Ryan et al (2000), , , Bonifacio et al (2002), Asplund et al (2006), Boesgaard et al (2005), and Bonifacio et al (2007).…”

Section: Bounds From Bbnmentioning

confidence: 99%

Time variation of the fine structure constant in the early universe and the Bekenstein model

Mosquera

Scóccola

Landau

et al. 2007

A&A

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Aims. We calculate the bounds on the variation in the fine structure constant at the time of primordial nucleosynthesis and at the time of neutral hydrogen formation. We used these bounds and other bounds from the late universe to test the Bekenstein model. Methods. We modified the Kawano code, CAMB, and CosmoMC to include the possible variation in the fine structure constant. We used observational primordial abundances of D, 4 He, and 7 Li, recent data from the cosmic microwave background, and the 2dFGRS power spectrum, to obtain bounds on the variation in α. We calculated a piecewise solution to the scalar field equation of the Bekenstein model in two different regimes: i) matter and radiation, ii) matter and cosmological constant. We match both solutions with the appropriate boundary conditions. We performed a statistical analysis, using the bounds obtained from the early universe and other bounds from the late universe to constrain the free parameters of the model. Results. Results are consistent with no variation in α for the early universe. Limits on α are inconsistent with the scale length of the theory l being larger than the Planck scale. Conclusions. In order to fit all observational and experimental data, the assumption l > L p implied in Bekenstein's model has to be relaxed.

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“…Thus, the observed linear relationships favor the first process more than the second. This is reinforced by the absence of significant O/H variations within the first 400 parsecs (Meyer et al 1998;André et al 2003;Oliveira et al 2006)…”

Section: A Link Between the Lc The Gould Belt And The D/h Pattern?mentioning

confidence: 98%

Some Observations Related to the Origin and Evolution of the Local Bubble/Local ISM

Lallement¹

2008

Space Sci Rev

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Variations in D/H and D/O from NewFar Ultraviolet Spectroscopic ExplorerObservations

Cited by 25 publications

References 70 publications

Magnetism, X-rays and accretion rates in WD 1145+017 and other polluted white dwarf systems

Magnetism, X-rays and accretion rates in WD 1145+017 and other polluted white dwarf systems

Time variation of the fine structure constant in the early universe and the Bekenstein model

Some Observations Related to the Origin and Evolution of the Local Bubble/Local ISM

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