The PICNIC Interferometry Camera at IOTA

Pedretti, E.; Millan-Gabet, R.; Monnier, John D.; Traub, W. A.; Carleton, N. P.; Berger, J.‐P.; Lacasse, M. G.; Schloerb, F. Peter; Brewer, Michael K.

doi:10.1086/383528

Cited by 33 publications

(32 citation statements)

References 28 publications

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“…Consequently, the detector achieves a frame rate of 0.85 kHz when reading 168 pixels (24 outputs times 7 spectral channels) in a nondestructive way. We characterized the readout noise following the same procedure as described by Pedretti et al (2004). We found a noise of ≈13 e − per read while Pedretti et al report ≈9 e − per read on this camera.…”

Section: The Detectormentioning

confidence: 91%

PIONIER: a 4-telescope visitor instrument at VLTI

Bouquin

Berger

Lazareff

et al. 2011

A&A

254

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Context. PIONIER stands for PrecisionAims. In this paper, we explain the instrumental concept and describe the standard operational modes and the data reduction strategy. We present the typical performance and discuss how to improve them. Methods. This paper is based on laboratory data obtained during the integrations at IPAG, as well as on-sky data gathered during the commissioning at VLTI. We illustrate the imaging capability of PIONIER on the binaries δ Sco and HIP11231. Results. PIONIER provides six visibilities and three independent closure phases in the H band, either in a broadband mode or with a low spectral dispersion (R = 40), using natural light (i.e. unpolarized). The limiting magnitude is Hmag = 7 in dispersed mode under median atmospheric conditions (seeing <1 , τ 0 > 3 ms) with the 1.8 m Auxiliary Telescopes. We demonstrate a precision of 0.5 deg on the closure phases. The precision on the calibrated visibilities ranges from 3% to 15% depending on the atmospheric conditions. Conclusions. PIONIER was installed and successfully tested as a visitor instrument for the VLTI. It permits high angular resolution imaging studies at an unprecedented level of sensitivity. The successful combination of the four 8 m Unit Telescopes in March 2011 demonstrates that VLTI is ready for four-telescope operation.

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Section: The Detectormentioning

confidence: 91%

PIONIER: a 4-telescope visitor instrument at VLTI

Bouquin

Berger

Lazareff

et al. 2011

A&A

254

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“…Light was split in two orthogonal polarization axes with a Wollaston prism. Finally the fringes were imaged with an acquistion camera using a PICNIC detector (Pedretti et al 2004). We observed α Ori in the H narrow-band filter (λ 0 = 1.64 μm, Δλ = 0.10 μm) during 6 days using 5 different configurations of the interferometer in order to get a rich uv coverage (see Table 1 and Fig.…”

Section: Observation and Data Reductionmentioning

confidence: 99%

Imaging the spotty surface of Betelgeuse in theHband

Haubois¹,

Perrin²,

Lacour³

et al. 2009

A&A

162

171

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Aims. This paper reports on H-band interferometric observations of Betelgeuse made at the three-telescope interferometer IOTA. We image Betelgeuse and its asymmetries to understand the spatial variation of the photosphere, including its diameter, limb darkening, effective temperature, surrounding brightness, and bright (or dark) star spots. Methods. We used different theoretical simulations of the photosphere and dusty environment to model the visibility data. We made images with parametric modeling and two image reconstruction algorithms: MIRA and WISARD. Results. We measure an average limb-darkened diameter of 44.28 ± 0.15 mas with linear and quadratic models and a Rosseland diameter of 45.03 ± 0.12 mas with a MARCS model. These measurements lead us to derive an updated effective temperature of 3600 ± 66 K. We detect a fully-resolved environment to which the silicate dust shell is likely to contribute. By using two imaging reconstruction algorithms, we unveiled two bright spots on the surface of Betelgeuse. One spot has a diameter of about 11 mas and accounts for about 8.5% of the total flux. The second one is unresolved (diameter < 9 mas) with 4.5% of the total flux. Conclusions. Resolved images of Betelgeuse in the H band are asymmetric at the level of a few percent. The MOLsphere is not detected in this wavelength range. The amount of measured limb-darkening is in good agreement with model predictions. The two spots imaged at the surface of the star are potential signatures of convective cells.

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“…This integrated optics component combines 3 input beams in a pairwise manner. Fringes were encoded in the time domain using piezo-electric path modulators, and detected with a near-infrared camera utilizing a PICNIC detector (Pedretti et al 2004). Betelgeuse was observed in the H band (16 400 ± 1000 Å, Fig.…”

Section: Observationsmentioning

confidence: 99%

Radiative hydrodynamics simulations of red supergiant stars

Chiavassa

Haubois

Young

et al. 2010

A&A

128

130

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Context. The red supergiant (RSG) Betelgeuse is an irregular variable star. Convection may play an important role in understanding this variability. Interferometric observations can be interpreted using sophisticated simulations of stellar convection. Aims. We compare the visibility curves and closure phases obtained from our 3D simulation of RSG convection with CO5BOLD to various interferometric observations of Betelgeuse from the optical to the H band to characterize and measure the convection pattern on this star. Methods. We use a 3D radiative-hydrodynamics (RHD) simulation to compute intensity maps in different filters and thus derive interferometric observables using the post-processing radiative transfer code OPTIM3D. The synthetic visibility curves and closure phases are compared to observations. Results. We provide a robust detection of the granulation pattern on the surface of Betelgeuse in both the optical and the H band based on excellent fits to the observed visibility points and closure phases. We determine that the Betelgeuse surface in the H band is covered by small to medium scale (5−15 mas) convection-related surface structures and a large (≈30 mas) convective cell. In this spectral region, H 2 O molecules are the main absorbers and contribute to both the small structures and the position of the first null of the visibility curve (i.e., the apparent stellar radius).

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The PICNIC Interferometry Camera at IOTA

Cited by 33 publications

References 28 publications

PIONIER: a 4-telescope visitor instrument at VLTI

PIONIER: a 4-telescope visitor instrument at VLTI

Imaging the spotty surface of Betelgeuse in theHband

Radiative hydrodynamics simulations of red supergiant stars

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