References of "Colavita, M. M"
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See detailConstraining the Exozodiacal Luminosity Function of Main-sequence Stars: Complete Results from the Keck Nuller Mid-infrared Surveys
Mennesson, B.; Millan-Gabet, R.; Serabyn, E. et al

in Astrophysical Journal (2014), 797

Forty-seven nearby main-sequence stars were surveyed with the Keck Interferometer mid-infrared Nulling instrument (KIN) between 2008 and 2011, searching for faint resolved emission from exozodiacal dust ... [more ▼]

Forty-seven nearby main-sequence stars were surveyed with the Keck Interferometer mid-infrared Nulling instrument (KIN) between 2008 and 2011, searching for faint resolved emission from exozodiacal dust. Observations of a subset of the sample have already been reported, focusing essentially on stars with no previously known dust. Here we extend this previous analysis to the whole KIN sample, including 22 more stars with known near- and/or far-infrared excesses. In addition to an analysis similar to that of the first paper of this series, which was restricted to the 8-9 mum spectral region, we present measurements obtained in all 10 spectral channels covering the 8-13 mum instrumental bandwidth. Based on the 8-9 mum data alone, which provide the highest signal-to-noise measurements, only one star shows a large excess imputable to dust emission (eta Crv), while four more show a significant (>3sigma) excess: beta Leo, beta UMa, zeta Lep, and gamma Oph. Overall, excesses detected by KIN are more frequent around A-type stars than later spectral types. A statistical analysis of the measurements further indicates that stars with known far-infrared (lambda >= 70 mum) excesses have higher exozodiacal emission levels than stars with no previous indication of a cold outer disk. This statistical trend is observed regardless of spectral type and points to a dynamical connection between the inner (zodi-like) and outer (Kuiper-Belt-like) dust populations. The measured levels for such stars are clustering close to the KIN detection limit of a few hundred zodis and are indeed consistent with those expected from a populat [less ▲]

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See detailAn interferometric study of the Fomalhaut inner debris disk II. Keck Nuller mid-infrared observations
Mennesson, B.; Absil, Olivier ULg; Lebreton, J. et al

in Astrophysical Journal (2013), 763

We report on high contrast mid-infrared observations of Fomalhaut obtained with the Keck Interferometer Nuller (KIN) showing a small resolved excess over the level expected from the stellar photosphere ... [more ▼]

We report on high contrast mid-infrared observations of Fomalhaut obtained with the Keck Interferometer Nuller (KIN) showing a small resolved excess over the level expected from the stellar photosphere. The measured null excess has a mean value of 0.35% +/- 0.10% between 8 and 11 microns and increases from 8 to 13 microns. Given the small field of view of the instrument, the source of this marginal excess must be contained within 2AU of Fomalhaut. This result is reminiscent of previous VLTI K-band observations, which implied the presence of a ~ 0.88% excess, and argued that thermal emission from hot dusty grains located within 6 AU from Fomalhaut was the most plausible explanation. Using a parametric 2D radiative transfer code and a Bayesian analysis, we examine different dust disk structures to reproduce both the near and mid-infrared data simultaneously. While not a definitive explanation of the hot excess of Fomalhaut, our model suggests that the most likely inner few AU disk geometry consists of a two-component structure, with two different and spatially distinct grain populations. The 2 to 11 microns data are consistent with an inner hot ring of very small (~ 10 to 300 nm) carbon-rich grains concentrating around 0.1AU. The second dust population consists of larger grains (size of a few microns to a few tens of microns) located further out in a colder region where regular astronomical silicates could survive, with an inner edge around 1AU. From a dynamical point of view, the presence of the inner concentration of sub-micron sized grains is surprising, as such grains should be expelled from the inner planetary system by radiation pressure within only a few years. This could either point to some inordinate replenishment rates (e.g. many grazing comets coming from an outer reservoir) or to the existence of some braking mechanism preventing the grains from moving out. [less ▲]

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See detailThe potential of rotating-baseline nulling interferometers operating within large single-telescope apertures
Serabyn, E.; Mennesson, B.; Martin, Stefan et al

in Danchi, W. C.; Delplancke, F.; Rajagopal, J. K. (Eds.) Optical and Infrared Interferometry II (2010, July 01)

The use of a rotating-baseline nulling interferometer for exoplanet detection was proposed several decades ago, but the technique has not yet been fully demonstrated in practice. Here we consider the ... [more ▼]

The use of a rotating-baseline nulling interferometer for exoplanet detection was proposed several decades ago, but the technique has not yet been fully demonstrated in practice. Here we consider the faint companion and exozodiacal disk detection capabilities of rotating-baseline nulling interferometers, such as are envisioned for space-based infrared nullers, but operating instead within the aperture of large single telescopes. In particular, a nulling interferometer on a large aperture corrected by a next-generation extreme adaptive optics system can provide deep interferometric contrasts, and also reach smaller angles (sub λ/D) than classical coronagraphs. Such rotating nullers also provide validation for an eventual space-based rotating-baseline nulling interferometer. As practical examples, we describe ongoing experiments with rotating nullers at Palomar and Keck, and consider briefly the case of the Thirty Meter Telescope. [less ▲]

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