High-angular and high-contrast VLTI observations from J to M band with the Asgard instrumental suite

Mortimer

Optical and Infrared Interferometry and Imaging VIII

et al. 2022

Self Cite

We present science cases and instrument design considerations for the BIFROST instrument that will open the short-wavelength (Y/J/H-band), high spectral dispersion (up to R=25,000) window for the VLT Interferometer. BIFROST will be part of the Asgard Suite of instruments and unlock powerful venues for studying accretion & mass-loss processes at the early/late stages of stellar evolution, for detecting accreting protoplanets around young stars, and for probing the spin-orbit alignment in directly-imaged planetary systems and multiple star systems. Our survey on GAIA binaries aims to provide masses and precision ages for a thousand stars, providing a legacy data set for improving stellar evolutionary models as well as for Galactic Archaeology. BIFROST will enable off-axis spectroscopy of exoplanets in the 0.025-1" separation range, enabling high-SNR, high spectral resolution follow-up of exoplanets detected with ELT and JWST. We give an update on the status of the project, outline our key technology choices, and discuss synergies with other instruments in the proposed Asgard Suite of instruments.

Section: Integration In Asgard Suitementioning

confidence: 99%

High spectral-resolution interferometry down to 1 micron with Asgard/BIFROST at VLTI: science drivers and project overview

Mortimer

Optical and Infrared Interferometry and Imaging VIII

et al. 2022

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Section: Introductionmentioning

confidence: 99%

“…BIFROST is a planned visitor instrument for the Very Large Telescope Interferometer (VLTI) and part of the ASGARD suite of instruments (Martinod et al 2022). 1 With its short wavelength (J band) and high spectral resolution (R = 25,000) will open up a new observational window at the VLTI. A few key science drivers include measuring precision dynamical masses and ages for GAIA binaries, measuring the spin-orbit alignment for directly imaged exoplanets and off-axis exoplanet spectroscopy (Kraus et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Beam combiner for the Asgard/BIFROST instrument

Mortimer

Optical and Infrared Interferometry and Imaging VIII

et al. 2022

Self Cite

BIFROST will be a short-wavelength (λ = 1.0 -1.7 µm) beam combiner for the VLT Interferometer, combining both high spatial (λ/2B = 0.8 mas) and spectral (up to R = 25,000) resolution. It will be part of the Asgard Suite of visitor instruments. The new window of high spectral resolution, short wavelength observations brings with it new challenges. Here we outline the instrumental design of BIFROST, highlighting which beam combiner subsystems are required and why. This is followed by a comparison All-In-One (AIO) beam combination scheme and an Integrated Optics (IO) scheme with ABCD modulation both in terms of expected sensitivity and the practical implementation of each system.

“…BIFROST (Beam-combination Instrument for studying the Formation & fundamental pRoperties Of Stars and planeTary systems) is an upcoming Very Large Telescope Interferometry (VLTI) visitor instrument as part of VLTI/Asgard instrument Suite. [1][2][3][4][5][6][7][8][9][10] BIFROST will operate in either a Y+J or a H band mode. The major components that we need to design for BIFROST include the spectrograph.…”

Section: Introductionmentioning

confidence: 99%

Spectrograph design for the Asgard/BIFROST spectro-interferometric instrument for the VLTI

Frangiamore

Optical and Infrared Interferometry and Imaging VIII

et al. 2022

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The BIFROST instrument will be the first VLTI instrument optimised for high spectral resolution up to R=25,000 and operate between 1.05 and 1.7 µm. A key component of the instrument will be the spectrograph, where we require a high throughput over a broad bandwidth. In this contribution, we discuss the four planned spectral modes (R=50, R=1000, R=5000, and R=25,000), the key spectral windows that we need to cover, and the technology choices that we have considered. We present our plan to use Volume Phase Holographic Gratings (VPHGs) to achieve a high efficiency > 85%. We present our preliminary optical design and our strategies for wavelength calibration.