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See detailExpanding the CHARA/FLUOR hot disk survey
Mennesson, B.; Scott, N.; Ten Brummelaar, T. et al

in Journal of Astronomical Instrumentation (2013), 2(2), 1340010

Little is presently known about the hot (>300 K) dust component of debris disks surrounding main sequence stars, similar to the zodiacal dust cloud found in the inner solar system.While extensive surveys ... [more ▼]

Little is presently known about the hot (>300 K) dust component of debris disks surrounding main sequence stars, similar to the zodiacal dust cloud found in the inner solar system.While extensive surveys have been carried out from space, the majority of detections have surprisingly come from the ground, where near infrared interferometric observations have recently revealed small (∼1%) resolved excesses around a dozen nearby main sequence stars. Most of these results have come from the CHARA array “FLUOR” instrument (Mt. Wilson, CA), which has demonstrated the best sensitivity worldwide so far for this type of studies, and has carried out an initial survey of ∼40 stars. In order to further understand the origin of this “hot dust phenomenon”, we will extend this initial survey to a larger number of stars and lower excess detection limits, i.e. higher visibility accuracy providing higher contrast measurements. To this end, two major instrumental developments are underway at CHARA. The first one aims at improving FLUOR’s sensitivity to a median K-band magnitude limit of 5 (making 200 targets available). The second development is based on a method that we recently developed for accurate (better than 0.1%) null depth measurements of stars, and that can be extended to regular interferometric visibility measurements. [less ▲]

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See detailThe radius and mass of the close solar twin 18 Scorpii derived from asteroseismology and interferometry
Bazot, Michaël; Ireland, M. J.; Huber, D. et al

in Astronomy and Astrophysics (2011), 526

The growing interest in solar twins is motivated by the possibility of comparing them directly to the Sun. To carry on this kind of analysis, we need to know their physical characteristics with precision ... [more ▼]

The growing interest in solar twins is motivated by the possibility of comparing them directly to the Sun. To carry on this kind of analysis, we need to know their physical characteristics with precision. Our first objective is to use asteroseismology and interferometry on the brightest of them: 18 Sco. We observed the star during 12 nights with HARPS for seismology and used the PAVO beam-combiner at CHARA for interferometry. An average large frequency separation 134.4 ± 0.3 μHz and angular and linear radiuses of 0.6759 ± 0.0062 mas and 1.010 ± 0.009 Rsun were estimated. We used these values to derive the mass of the star, 1.02 ± 0.03 Msun. [less ▲]

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See detailDust in the inner regions of debris disks around A stars
Akeson, R. L.; Ciardi, D. R.; Millan-Gabet, R. et al

in Astrophysical Journal (2009), 691

We present infrared interferometric observations of the inner regions of two A-star debris disks, beta Leo and zeta Lep, using the FLUOR instrument at the CHARA interferometer on both short (30 m) and ... [more ▼]

We present infrared interferometric observations of the inner regions of two A-star debris disks, beta Leo and zeta Lep, using the FLUOR instrument at the CHARA interferometer on both short (30 m) and long (> 200 m) baselines. For the target stars, the short-baseline visibilities are lower than expected for the stellar photosphere alone, while those of a check star, delta Leo, are not. We interpret this visibility offset of a few percent as a near-infrared (NIR) excess arising from dust grains which, due to the instrumental field of view, must be located within several AU of the central star. For beta Leo, the NIR excess-producing grains are spatially distinct from the dust which produces the previously known mid-infrared (MIR) excess. For zeta Lep, the NIR excess may be spatially associated with the MIR excess-producing material. We present simple geometric models which are consistent with the NIR and MIR excesses and show that for both objects, the NIR-producing material is most consistent with a thin ring of dust near the sublimation radius, with typical grain sizes smaller than the nominal radiation pressure blowout radius. Finally, we discuss possible origins of the NIR-emitting dust in the context of debris disk evolution models. [less ▲]

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See detailInfrared Interferometric Gravity Darkening Observations of Vega with CHARA/FLUOR
Aufdenberg, J.; Mérand, A.; Coudé Du Foresto, V. et al

in Coudé du Foresto, Vincent; Rouan, Daniel; Rousset, Gérard (Eds.) Visions for Infrared Astronomy (2006, March)

We have obtained high-precision measurements of Vega at projected baselines between 103 m and 273 m with the CHARA Array using the (FLUOR) beam combiner in the K' band. A strongly gravity-darkened model ... [more ▼]

We have obtained high-precision measurements of Vega at projected baselines between 103 m and 273 m with the CHARA Array using the (FLUOR) beam combiner in the K' band. A strongly gravity-darkened model atmosphere is in general agreement with both our interferometric data and archival spectrophotometry. This model indicates that Vega is rotating at 91%ofitsangular break-uprateandthatthepole-to-equator effectivetemperaturedifference is 2250 K. [less ▲]

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