@article{13410,
  author = {T. Winterhalder and S. Lacour and J. Dexter and et. al},
  title = {Combining Gaia and GRAVITY: Characterising Five New Directly Detected Substellar Companions},
  abstract = {<p>Precise mass constraints are vital for the characterisation of brown dwarfs and exoplanets. Here, we present how the combination of data obtained by Gaia and GRAVITY can help enlarge the sample of substellar companions with measured dynamical masses. We show how the Non-Single-Star (NSS) two-body orbit catalogue contained in Gaia DR3 can be used to inform high angular resolution follow-up observations with GRAVITY. Applying the method presented in this work for eight Gaia candidate systems, we detect all eight predicted companions, seven of which being previously unknown and five of substellar nature. Among the sample is Gaia DR3 2728129004119806464 B, which - detected at a angular separation of (34.01&nbsp;±&nbsp;0.15) mas from the host - is the closest substellar companion ever imaged. In combination with the system's distance this translates to a physical separation of (1.054&nbsp;±&nbsp;0.002) AU. The GRAVITY data are then used to break the host-companion mass degeneracy inherent to the Gaia NSS orbit solutions as well as to constrain the orbital solutions of the respective target systems. Knowledge of the companion masses enables us to further characterise them in terms of their age, effective temperature and radius by the application of evolutionary models. The results serve as an independent validation of the orbital solutions published in the NSS two-body orbit catalogue and show that the combination of astrometric survey missions and high-angular resolution direct imaging hold great promise for efficiently increasing the sample of directly-imaged companions in the future, especially in the light of the Gaia's upcoming DR4 and the advent of GRAVITY+.</p>
},
  year = {2024},
  journal = {Submitted},
  url = {https://arxiv.org/abs/2403.13055v1},
}