Two-Dimensional Classical Wave Localization in a Third Sound System

Luhman, Dwight; Herrmann, Justin; Hallock, R. B.

doi:10.1063/1.2354691

Cited by 2 publications

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“…Mayne & Naylor 2008;Baraffe, Chabrier & Gallardo 2009), the high fraction of disc-bearing M-stars in η Chamaleontis, aged 8 Myr, has been interpreted as evidence for longer disc lifetimes around late-type stars (Sicilia-Aguilar et al 2009). Furthermore, there is tentative evidence that the frequency of infrared excess emission appears to decrease less steeply with age as the mass of the central object decreases; this result, however, is not yet conclusive because only a few disc fractions have been measured for low-mass stars older than 3 Myr (Carpenter et al 2006;Luhman 2009).…”

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confidence: 99%

On the lifetime of discs around late-type stars

Ercolano

Bastian

Spezzi

et al. 2011

Monthly Notices of the Royal Astronomical Society

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We address the question of whether protoplanetary discs around low‐mass stars (e.g. M‐dwarfs) may be longer lived than their solar‐type counterparts. This question is particularly relevant in assessing the planet‐making potential of these lower mass discs. Given the uncertainties inherent to age‐dating young stars, we propose an alternative approach that is to analyse the spatial distribution of disc‐bearing low‐mass stars and compare it to that of disc‐bearing solar‐type stars in the same cluster. A significant age difference between the two populations should be reflected in their average nearest‐neighbour distance (normalized to the number of sources), where the older population should appear more spread out. To this aim, we perform a Minimum Spanning Tree (MST) analysis on the spatial distribution of disc‐bearing young stellar objects (YSOs) in six nearby low‐mass star‐forming regions. We find no evidence for significant age differences between the disc‐bearing low‐mass (later than M2) and ‘solar‐type’ (earlier than M2) stars in these regions. We model our results by constructing and analysing synthetic fractal distributions that we evolve for typical values of the velocity dispersions. A comparison of results obtained using simple models to the results from our MST analysis suggests that the lifetime of discs around M‐stars is similar to that of discs around solar‐type stars. Furthermore, a model‐independent spatial analysis of the observations robustly shows that any age differences between the two samples must be smaller than the average age difference between disc‐bearing classical T Tauri stars and discless weak‐lined T Tauri stars.

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confidence: 99%

On the lifetime of discs around late-type stars

Ercolano

Bastian

Spezzi

et al. 2011

Monthly Notices of the Royal Astronomical Society

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“…However, in those experiments there is room left to raise accuracy at least by the order of magnitude. 25 We have also studied finite-size scaling of the width of the dissipation peak for a given disorder strength. Its broadening one-to-one resembles the finite-size broadening of the superfluid density jump (correspondingly, po- sition of the peak shifts to higher chemical potential as r ω is increased).…”

Section: B Broadening Of the Kt Transitionsmentioning

confidence: 99%

Effect of disorder on the superfluid transition in two-dimensional systems

Balabanyan

2007

Phys. Rev. B

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In recent experiments on thin 4 He films absorbed to rough surfaces Luhman and Hallock (Ref. 1) attempted to observe KT features of the superfluid-normal transition of this strongly disordered 2D bosonic system. It came as a surprise that while peak of dissipation was measured for a wide range of surface roughness there were no indications of the theoretically expected universal jump of the areal superfluid density for the strongly disordered samples. We test the hypothesis that this unusual behavior is a manifestation of finite-size effects by numerical study of the corresponding 2D bosonic model with strong diagonal disorder. We demonstrate that the discontinuous features of the underlying KT transition are severely smoothed out for finite system sizes (or finite frequency measurements). We resolve the universal discontinuity of the areal superfluid density by fitting our data to the KT renormalization group equations for finite systems. In analogy to our simulations, we suggest that in experiments on strongly disordered 2D bosonic systems the very existence of the KT scenario can and should be revealed only from a proper finite-size scaling of the data (for 4 He films finite-size scaling can be effectively controlled by the scaling of finite frequency of measurements). We also show relevance of our conclusions for a wider class of systems, such as superconducting granular films, Josephson junction arrays, and ultracold atomic gases, where similar difficulties appear in experiments designed to verify KT transition (especially in disordered cases).

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Two-Dimensional Classical Wave Localization in a Third Sound System

Cited by 2 publications

References 0 publications

On the lifetime of discs around late-type stars

On the lifetime of discs around late-type stars

Effect of disorder on the superfluid transition in two-dimensional systems

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