1. Results from The COPAINS Pilot Survey: Four new brown dwarfs and a high companion detection rate for accelerating stars
- Author
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Bonavita, M, Fontanive, C, Gratton, R, Mužić, K, Desidera, S, Mesa, D, Biller, B, Scholz, A, Sozzetti, A, Squicciarini, V, University of St Andrews. School of Physics and Astronomy, and University of St Andrews. St Andrews Centre for Exoplanet Science
- Subjects
Earth and Planetary Astrophysics (astro-ph.EP) ,visual [(Stars) binaries] ,520 Astronomy ,FOS: Physical sciences ,DAS ,Astronomy and Astrophysics ,Astrometry ,Astrophysics::Cosmology and Extragalactic Astrophysics ,adaptive optics [Instrumentation] ,low mass [Stars] ,QC Physics ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,brown dwarfs [Stars] ,QB Astronomy ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,QC ,Astrophysics::Galaxy Astrophysics ,QB ,Astrophysics - Earth and Planetary Astrophysics - Abstract
The last decade of direct imaging (DI) searches for sub-stellar companions has uncovered a widely diverse sample that challenges the current formation models, while highlighting the intrinsically low occurrence rate of wide companions, especially at the lower end of the mass distribution. These results clearly show how blind surveys, crucial to constrain the underlying planet and sub-stellar companion population, are not an efficient way to increase the sample of DI companions. It is therefore becoming clear that efficient target selection methods are essential to ensure a larger number of detections. We present the results of the COPAINS Survey conducted with SPHERE/VLT, searching for sub-stellar companions to stars showing significant proper motion differences (Delta mu) between different astrometric catalogues. We observed twenty-five stars and detected ten companions, including four new brown dwarfs: HIP 21152 B, HIP 29724 B, HD 60584 B and HIP 63734 B. Our results clearly demonstrates how astrometric signatures, in the past only giving access to stellar companions, can now thanks to Gaia reveal companions well in the sub-stellar regime. We also introduce FORECAST (Finley Optimised REtrieval of Companions of Accelerating STars), a tool which allows to check the agreement between position and mass of the detected companions with the measured Delta mu. Given the agreement between the values of the masses of the new sub-stellar companions from the photometry with the model-independent ones obtained with FORECAST, the results of COPAINS represent a significant increase of the number of potential benchmarks for brown dwarf and planet formation and evolution theories., Accepter for publication in MNRAS. 20 pages, 8 figures, 8 tables. Full version of Table 2, 3 and 4 available with the source files
- Published
- 2022
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