PIONIER: a 4-telescope visitor instrument at VLTI

Bouquin, J.-B. Le; Berger, J.‐P.; Lazareff, B.; Zins, G.; Haguenauer, Pierre; Jocou, L.; Kern, P.; Millan-Gabet, R.; Traub, Wesley A.; Absil, Olivier; Augereau, J.-C.; Benisty, M.; Blind, N.; Bonfils, X.; Bourget, P.; Delboulbé, A.; Feautrier, Philippe; Germain, M. E.; Gitton, Ph.; Gillier, D.; Kiekebusch, M.; Kluska, J.; Knudstrup, J.; Labeye, P.; Lizon, Jean-Louis; Monin, Jean‐Louis; Magnard, Y.; Malbet, Fabien; Maurel, D.; Ménard, F.; Micallef, Mark; Michaud, L.; Montagnier, G.; Morel, S.; Moulin, T.; Perraut, K.; Popovic, D.; Rabou, Patrick; Rochat, S.; Rojas, Claudia Marcela; Roussel, Fernand; Roux, A.; Stadler, Eric; Štefl, S.; Tatulli, E.; Ventura, N.

doi:10.1051/0004-6361/201117586

Cited by 253 publications

(100 citation statements)

References 38 publications

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“…First, it was seen in AMBER 12 data, but it was considered as an instrumental defect. Now, the same effect has been observed with PIONIER 13 . We try to explain this effect astrophysically, claiming that the image of the object is varying through the different spectral channels inside the same spectral band, and we propose three techniques in order to take it into account and to be able to reconstruct images.…”

Section: Introductionsupporting

confidence: 79%

Intrincate visibility effects from resolved emission of young stellar objects: the case of MWC158 observed with the VLTI

Kluska

Malbet

Berger

et al. 2012

Optical and Infrared Interferometry III

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In the course of our VLTI young stellar object PIONIER imaging program, we have identified a strong visibility chromatic dependency that appeared in certain sources. This effect, rising value of visibilities with decreasing wavelengths over one base, is also present in previous published and archival AMBER data. For Herbig AeBe stars, the H band is generally located at the transition between the star and the disk predominance in flux for Herbig AeBe stars. We believe that this phenomenon is responsible for the visibility rise effect. We present a method to correct the visibilities from this effect in order to allow "gray" image reconstruction software, like Mira, to be used. In parallel we probe the interest of carrying an image reconstruction in each spectral channel and then combine them to obtain the final broadband one. As an illustration we apply these imaging methods to MWC158, a (possibly Herbig) B[e] star intensively observed with PIONIER. Finally, we compare our result with a parametric model fitted onto the data.

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Section: Introductionsupporting

confidence: 79%

Intrincate visibility effects from resolved emission of young stellar objects: the case of MWC158 observed with the VLTI

Kluska

Malbet

Berger

et al. 2012

Optical and Infrared Interferometry III

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“…Imaging broad-band interferometric observations were obtained at t = 12.81 d (H ≈ 6) with the PIONIER visitor instrument (Berger et al 2010;Le Bouquin et al 2011). These observations provided the simultaneous measurement of six absolutely calibrated visibilities and four closure phases in the H-band, therefore allowing the study of the spatial morphology of the near-infrared emission.…”

Section: Observationsmentioning

confidence: 99%

The 2011 outburst of the recurrent nova T Pyxidis. Evidence for a face-on bipolar ejection

Chesneau¹,

Meilland²,

Banerjee³

et al. 2011

A&A

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Aims. T Pyx is the first recurrent nova ever historically studied. It was seen in outburst six times between 1890 and 1966 and then not for 45 years. We report on near-IR interferometric observations of the recent outburst of 2011. Methods. We obtained near-IR observations of T Pyx at dates ranging from t = 2.37 d to t = 48.2 d after the outburst, with the CLASSIC recombiner located at the CHARA array and with the PIONIER and AMBER recombiners located at the VLTI array. These data are supplemented with near-IR photometry and spectra obtained at Mount Abu, India. We compare expansion of the H and K band continua and the Brγ emission line, and infer information on the kinematics and morphology of the early ejecta. Results. Slow expansion velocities were measured (≤300 km s −1 ) before t = 20 d. From t = 28 d on, the AMBER and PIONIER continuum visibilities (K and H band, respectively) are best simulated with a two-component model consisting of an unresolved source plus an extended source whose expansion velocity onto the sky plane is lower than ∼700 km s −1 . The expansion of the Brγ lineforming region, as inferred at t = 28 d and t = 35 d, is slightly larger, implying velocities in the range 500−800 km s −1 , which is still strikingly lower than the velocities of 1300−1600 km s −1 inferred from the Doppler width of the line. Moreover, a remarkable pattern was observed in the Brγ differential phases. A semi-quantitative model using a bipolar flow with a contrast of 2 between the pole and equator velocities, an inclination of i = 15• , and a position angle PA = 110• provides a good match to the AMBER observables. At t = 48 d, a PIONIER dataset confirms the two-component nature of the H band emission, consisting of an unresolved stellar source and an extended region whose appearance is circular and symmetric within error bars. Conclusions. These observations are most simply interpreted within the frame of a bipolar model, oriented nearly face-on. This finding has profound implications for interpreting past, current, and future observations of the expanding nebula.

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“…, 6 telescopes which corresponds to actual interferometers and up to 100 N λ . Note as an example that N λ > 500 for the high resolution mode of AMBER [34], and N λ = 3 for the standard uses of PIONIER [21].…”

Section: Practical Remarksmentioning

confidence: 99%

PAINTER: a spatiospectral image reconstruction algorithm for optical interferometry

et al. 2014

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Astronomical optical interferometers sample the Fourier transform of the intensity distribution of a source at the observation wavelength. Because of rapid perturbations caused by atmospheric turbulence, the phases of the complex Fourier samples (visibilities) cannot be directly exploited. Consequently, specific image reconstruction methods have been devised in the last few decades. Modern polychromatic optical interferometric instruments are now paving the way to multiwavelength imaging. This paper is devoted to the derivation of a spatio-spectral ("3D") image reconstruction algorithm, coined PAINTER (Polychromatic opticAl INTErferometric Reconstruction software). The algorithm relies on an iterative process, which alternates estimation of polychromatic images and of complex visibilities. The complex visibilities are not only estimated from squared moduli and closure phases, but also differential phases, which helps to better constrain the polychromatic reconstruction. Simulations on synthetic data illustrate the efficiency of the algorithm and in particular the relevance of injecting a differential phases model in the reconstruction.

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PIONIER: a 4-telescope visitor instrument at VLTI

Cited by 253 publications

References 38 publications

Intrincate visibility effects from resolved emission of young stellar objects: the case of MWC158 observed with the VLTI

Intrincate visibility effects from resolved emission of young stellar objects: the case of MWC158 observed with the VLTI

The 2011 outburst of the recurrent nova T Pyxidis. Evidence for a face-on bipolar ejection

PAINTER: a spatiospectral image reconstruction algorithm for optical interferometry

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