Speaker
Description
We present the exoplanet and planet formation science case for a new beam combination instrument for ESO’s VLT Interferometer, named BIFROST. This instrument is funded through the European Research Council and is due to be commissioned on Paranal in 2026 as part of the "Asgard Suite" of VLTI visitor instruments.
BIFROST will be the first VLTI instrument optimised for short wavelengths (1-1.7 micrometer) and high spectral resolution (up to R=25,000). This will allow us to measure the alignment between the stellar spin axis and the planetary orbital axis — even for wide-separation systems where this information is inaccessible with other techniques. These constraints will provide unique insights on the dynamical processes that shape system architectures.
To characterise the planets themselves, BIFROST will utilise dual-field interferometry, where the star-light suppression from adaptive optics is combined with star-light suppression from interferometry by placing the instrument fiber off-axis and adjusting the optical path delay to record at the predicted delay position of the planet. BIFROST will be able to employ this method in J and H-band, providing access to additional molecular tracers, such as the O2 absorption bands. These tracers are highly complementary to the K-band probed by GRAVITY and provide further constraints for atmospheric retrieval.
Finally, we will discuss the prospect of using BIFROST's high spectral and high angular resolution to study accretion onto young planets. Resolving the gas kinematics in circumplanetary discs would enable not only a direct mass measurement, but also inform us how planets gain their mass.
