Searching for faint companions with VLTI/PIONIER

Absil, Olivier; Bouquin, Jean-Baptiste Le; Berger, J.‐P.; Lagrange, Anne-Marie; Chauvin, G.; Lazareff, B.; Zins, G.; Haguenauer, Pierre; Jocou, L.; Kern, P.; Millan-Gabet, R.; Rochat, S.; Traub, W.

doi:10.1051/0004-6361/201117719

Cited by 58 publications

(92 citation statements)

References 27 publications

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“…The closure phases were also analysed independently using the method presented in Absil et al (2011), and the results agreed excellently. HD 150136 was clearly resolved on both dates with a slight decrease in separation between June and August (Table 2).…”

Section: Long Baseline Interferometrymentioning

confidence: 83%

Three-dimensional orbits of the triple-O stellar system HD 150136

Sana

Bouquin

Mahy

et al. 2013

A&A

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Context. HD 150136 is a triple hierarchical system and a non-thermal radio emitter. It is formed by an O3−3.5 V + O5.5−6 V close binary and a more distant O6.5−7 V tertiary. So far, only the inner orbital properties have been reliably constrained. Aims. To quantitatively understand the non-thermal emission process, accurate knowledge of the physical and orbital properties of the object is crucial. Here, we aim to investigate the orbital properties of the wide system and to constrain the inclinations of the inner and outer binaries, and with these the absolute masses of the system components. Methods. We used the PIONIER combiner at the Very Large Telescope Interferometer to obtain the very first interferometric measurements of HD 150136. We combined the interferometric observations with new and existing high-resolution spectroscopic data to derive the orbital solution of the outer companion in the three-dimensional space. Results. The wide system is clearly resolved by PIONIER, with a projected separation on the plane of the sky of about 9 milli-arcsec. The best-fit orbital period, eccentricity, and inclination are 8.2 yr, 0.73, and 108• . We constrain the masses of the three stars of the system to 63 ± 10, 40 ± 6, and 33 ± 12 M for the O3−3.5 V, O5.5−6 V, and O6.5−7 V components. Conclusions. The dynamical masses agree within errors with the evolutionary masses of the components. Future interferometric and spectroscopic monitoring of HD 150136 should allow one to reduce the uncertainties to a few per cent only and to accurately constrain the distance to the system. This makes HD 150136 an ideal system to quantitatively test evolutionary models of high-mass stars as well as the physics of non-thermal processes occurring in O-type systems.

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Section: Long Baseline Interferometrymentioning

confidence: 83%

Three-dimensional orbits of the triple-O stellar system HD 150136

Sana

Bouquin

Mahy

et al. 2013

A&A

Self Cite

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“…For a wider range, the loss of coherence caused by spectral smearing of the companion is the main limitation because it degrades the dynamic range. A complete discussion about the search region is presented by Absil et al (2011) and Le Bouquin & Absil (2012). The main limitation is the spectral sampling compared to the relative position of the component, i.e., to avoid a significant smearing we need R > ρB p /λ, with R, B p and ρ the spectral resolution, the projected baseline, and the separation, respectively.…”

Section: Detection Methodsmentioning

confidence: 99%

Robust high-contrast companion detection from interferometric observations

Gallenne

Mérand

Kervella

et al. 2015

A&A

130

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Context. Long-baseline interferometry is an important technique to spatially resolve binary or multiple systems in close orbits. By combining several telescopes together and spectrally dispersing the light, it is possible to detect faint components around bright stars in a few hours of observations. Aims. We provide a rigorous and detailed method to search for high-contrast companions around stars, determine the detection level, and estimate the dynamic range from interferometric observations. Methods. We developed the code CANDID (Companion Analysis and Non-Detection in Interferometric Data), a set of Python tools that allows us to search systematically for point-source, high-contrast companions and estimate the detection limit using all interferometric observables, i.e., the squared visibilities, closure phases and bispectrum amplitudes. The search procedure is made on a N × N grid of fit, whose minimum needed resolution is estimated a posteriori. It includes a tool to estimate the detection level of the companion in the number of sigmas. The code CANDID also incorporates a robust method to set a 3σ detection limit on the flux ratio, which is based on an analytical injection of a fake companion at each point in the grid. Our injection method also allows us to analytically remove a detected component to 1) search for a second companion; and 2) set an unbiased detection limit. Results. We used CANDID to search for the companions around the binary Cepheids V1334 Cyg, AX Cir, RT Aur, AW Per, SU Cas, and T Vul. First, we showed that our previous discoveries of the components orbiting V1334 Cyg and AX Cir were detected at >25σ and >13σ, respectively. The astrometric positions and flux ratios provided by CANDID for these two stars are in good agreement with our previously published values. The companion around AW Per is detected at more than 15σ with a flux ratio of f = 1.22 ± 0.30%, and it is located at ρ = 32.16 ± 0.29 mas and PA = 67.1 ± 0.3• . We made a possible detection of the companion orbiting RT Aur with f = 0.22 ± 0.11%, and at ρ = 2.10 ± 0.23 mas and PA = −136 ± 6• . It was detected at 3.8σ using the closure phases only, and so more observations are needed to confirm the dectection. No companions were detected around SU Cas and T Vul. We also set the detection limit for possible undetected companions around these stars. We found that there is no companion with a spectral type earlier than B7V, A5V, F0V, B9V, A0V, and B9V orbiting the Cepheids V1334 Cyg, AX Cir, RT Aur, AW Per, SU Cas, and T Vul, respectively. This work also demonstrates the capabilities of the MIRC and PIONIER instruments, which can reach a dynamic range of 1:200, depending on the angular distance of the companion and the (u, v) plane coverage. In the future, we plan to work on improving the sensitivity limits for realistic data through better handling of the correlations.

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“…It has been claimed that differential interferometry could be used to obtain spectroscopic information, and determine both the planetary mass, and the orbit inclination of extrasolar planets around nearby stars (Segransan et al 2000;Lopez et al 2000;Joergens & Quirrenbach 2004;Renard et al 2008;Zhao et al 2008;van Belle 2008;Matter et al 2010;Absil et al 2011;Zhao et al 2011). However, current interferometers lack sufficient accuracy for such a detection.…”

Section: Closure Phases and Perspectives For Hot Jupiter Detectionmentioning

confidence: 99%

Three-dimensional interferometric, spectrometric, and planetary views of Procyon

Chiavassa

Bigot

Kervella

et al. 2012

A&A

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Context. Procyon is one of the brightest stars in the sky and one of our nearest neighbours. It is therefore an ideal benchmark object for stellar astrophysics studies using interferometric, spectroscopic, and asteroseismic techniques. Aims. We use a new realistic three-dimensional (3D) radiative-hydrodynamical (RHD) model atmosphere of Procyon generated with the Stagger Code and synthetic spectra computed with the radiative transfer code Optim3D to re-analyze interferometric and spectroscopic data from the optical to the infrared. We provide synthetic interferometric observables that can be validated using observations. Methods. We computed intensity maps from a RHD simulation in two optical filters centered on 500 and 800 nm (Mark III) and one infrared filter centered on 2.2 μm (Vinci). We constructed stellar disk images accounting for the center-to-limb variations and used them to derive visibility amplitudes and closure phases. We also computed the spatially and temporally averaged synthetic spectrum from the ultraviolet to the infrared. We compare these observables to Procyon data. Results. We study the impact of the granulation pattern on center-to-limb intensity profiles and provide limb-darkening coefficients in the optical as well as in the infrared. We show how the convection-related surface structures affect the visibility curves and closure phases with clear deviations from circular symmetry, from the 3rd lobe on. These deviations are detectable with current interferometers using closure phases. We derive new angular diameters at different wavelengths with two independent methods based on 3D simulations. We find that θ Vinci = 5.390 ± 0.03 mas, which we confirm by comparison with an independent asteroseismic estimation (θ seismic = 5.360 ± 0.07 mas. The resulting T eff is 6591 K (or 6556 K depending on the bolometric flux used), which is consistent with the value of T eff,IR = 6621 K found with the infrared flux method. We measure a surface gravity log g = 4.01 ± 0.03 [cm/s 2 ] that is higher by 0.05 dex than literature values. Spectrophotometric comparisons with observations provide very good agreement with the spectral energy distribution and photometric colors, allowing us to conclude that the thermal gradient in the simulation matches Procyon fairly well. Finally, we show that the granulation pattern of a planet-hosting Procyon-like star has a non-negligible impact on the detection of hot Jupiters in the infrared using interferometry closure phases. It is then crucial to have a comprehensive knowledge of the host star to directly detect and characterize hot Jupiters. In this respect, RHD simulations are very important to achieving this aim.

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Searching for faint companions with VLTI/PIONIER

Cited by 58 publications

References 27 publications

Three-dimensional orbits of the triple-O stellar system HD 150136

Three-dimensional orbits of the triple-O stellar system HD 150136

Robust high-contrast companion detection from interferometric observations

Three-dimensional interferometric, spectrometric, and planetary views of Procyon

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