SPICA, a new 6T visible beam combiner for CHARA: science, design and interfaces

Mourard, D.; Nardetto, N.; Brummelaar, T. ten; Bailet, C.; Bério, Philippe; Bresson, Y.; Cassaing, F.; Clausse, J. M.; Dejonghe, J.; Lagarde, S.; Martinod, Marc-Antoine; Michau, Vincent; Perraut, K.; Petit, Cyril; Tallon, Michel; Tallon–Bosc, I.

doi:10.1117/12.2311869

Cited by 7 publications

(5 citation statements)

References 34 publications

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“…Even though the survey presented above constitutes just the core of the science objective of CHARA/SPICA, 20,21 the expected instrumental capabilities of the instrument will enable many other programs ‡ . Initially designed for high sensitivity and high precision measurements, the instrument offers three different spectral resolution (200, 4000, 13000) with spectral bands of 300, 90 and 30 nm, respectively.…”

Section: Additional Programs and Expected Performancementioning

confidence: 99%

“…One of the most critical aspects of the commissioning of SPICA has been to characterize the quality of the injection of the light into the single mode fibers. Knowing that SPICA is working behind an adaptive optics system not able to produce high Strehl ratio 25 in the visible, we decided 21 to help the injection by the addition of a fast tip/tilt mirror. During the commissioning we demonstrated that these tip/tilt stages are able to work at a frequency of 100Hz (currently limited by the USB readout mode of the ANDOR detector) up to magnitude 8.…”

Section: Level Of Injectionmentioning

confidence: 99%

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CHARA/SPICA: a 6-telescope visible instrument for the CHARA Array

Mourard,

Berio,

Pannetier

et al. 2022

Preprint

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With a possible angular resolution down to 0.1-0.2 millisecond of arc using the 330 m baselines and the access to the 600-900 nm spectral domain, the CHARA Array is ideally configured for focusing on precise and accurate fundamental parameters of stars. CHARA/SPICA (Stellar Parameters and Images with a Cophased Array) aims at performing a large survey of stars all over the Hertzsprung-Russell diagram. This survey will also study the effects of the different kinds of variability and surface structure on the reliability of the extracted fundamental parameters. New surface-brightness-colour relations will be extracted from this survey, for general purposes on distance determination and the characterization of faint stars. SPICA is made of a visible 6T fibered instrument and of a near-infrared fringe sensor. In this paper, we detail the science program and the main characteristics of SPICA-VIS. We present finally the initial performance obtained during the commissioning.

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Section: Additional Programs and Expected Performancementioning

confidence: 99%

Section: Level Of Injectionmentioning

confidence: 99%

CHARA/SPICA: a 6-telescope visible instrument for the CHARA Array

Mourard,

Berio,

Pannetier

et al. 2022

Preprint

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“…To overcome these difficulties, the use of single mode fibres has been proposed very early in the 80's (Connes et al, 1985). After injection of the light at each telescope focus, the spatial filtering allows to get highly calibrated fringes, as demonstrated in various recombining instruments like FLUOR (Coudé du Foresto et al, 2003), MIRC (Monnier et al, 2006) or SPICA (Mourard et al, 2018). This experimental configuration reduces the number of freedom degree to be controlled, limits the diffraction effects at the propagation in the delay lines and significantly enhances the overall throughput of the instrument thanks to the tremendous performances of the fibre optic transmission.…”

Section: Introductionmentioning

confidence: 99%

Outdoor fibre link between two telescopes and the lab of the CHARA array at 810 nm. Demonstration of the optical path servo control

Julie,

Ludovic,

François

et al. 2024

Exp Astron

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In the framework of the ALOHA (Astronomical Light Optical Hybrid Analysis) project, dedicated to high resolution imaging in the L-band using optical fibre and nonlinear optics, we have implemented a servo controlled hectometric outdoor fibre link between two telescopes and the recombination beam facility of the CHARA telescope array. A twostage servo system using optical fibre modulator, fibre delay line, and a metrology laser at 1064 nm allows to stabilise the optical path difference within 3 nm RMS over a 3000 s record. Using an internal source at 810 nm, the signal-to-noise ratio of the fringe modulation peak is enhanced by a factor better than two when the servo control is switched on. This study can be also considered as a seminal work towards very long base fibre linked telescope arrays and allows to scale the perturbative environment of an outdoor fibre link.

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“…For fast rotating early-type stars, the best way to determine i seems to be interferometry, but the angular diameter should not be too small. Presently, 1.5 milliarcsec (mas) seems to be the minimum size, but in the near future with the forthcoming Space Infrared Telescope for Cosmology and Astrophysics (SPICA) to be implemented on the Center for High Angular Resolution Astronomy (CHARA) array (Mourard et al 2018), this limit may be reduced to 0.8 mas. Nevertheless, this new limit is still stringent on the number of early-type stars that can be analysed since they should typically be closer than 30 pc from the Sun.…”

Section: Introductionmentioning

confidence: 99%

Photometric determination of rotation axis inclination, rotation rate, and mass of rapidly rotating intermediate-mass stars

Lazzarotto,

Hui-Bon-Hoa,

Rieutord

2023

A&A

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Context. Intermediate-mass stars are often fast rotators, and hence are centrifugally flattened and notably affected by gravity darkening. To analyse this kind of stars properly, one must resort to 2D models to compute the visible radiative flux and to take the geometrical effect of the star inclination into account. Aims. Assuming a given stellar age and chemical composition, our aim is to derive the mass and rotation rates of main sequence fast rotating stars, along with their inclination, from photometric quantities influenced by gravity darkening. Methods. We chose three observables that vary with mass, rotation, and inclination: the temperature derived by the infrared flux method TIRFM, the Strömgren c1 index, and a second index c2 built in the same way as the c1 index, but sensitive to the UV side of the Balmer jump. These observables are computed from synthetic spectra produced with the PHOENIX code and rely on a 2D stellar structure from the ESTER code. These quantities are computed for a grid of models in the range 2–7 M⊙, and rotation rates from 30% to 80% of the critical rate. Then, for any triplet (TIRFM, c1, c2), we try to retrieve the mass, rotation rate, and inclination using a Levenberg-Marquardt scheme, after a selection step to find the most suitable starting models. Results. Hare-and-hound tests showed that our algorithm can recover the mass, rotation rate, and inclination with a good accuracy. The difference between input and retrieved parameters is negligible for models lying on the grid and is less than a few percent otherwise. An application to the real case of Vega showed that the u filter is located in a spectral region where the modelled and observed spectra are discrepant, and led us to define a new filter. Using this new filter and subsequent index, the Vega parameters are also retrieved with satisfactory accuracy. Conclusions. This work opens the possibility to determine the fundamental parameters of rapidly rotating early-type stars from photometric space observations.

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SPICA, a new 6T visible beam combiner for CHARA: science, design and interfaces

Cited by 7 publications

References 34 publications

CHARA/SPICA: a 6-telescope visible instrument for the CHARA Array

CHARA/SPICA: a 6-telescope visible instrument for the CHARA Array

Outdoor fibre link between two telescopes and the lab of the CHARA array at 810 nm. Demonstration of the optical path servo control

Photometric determination of rotation axis inclination, rotation rate, and mass of rapidly rotating intermediate-mass stars

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