Results from The COPAINS Pilot Survey: Four new brown dwarfs and a high companion detection rate for accelerating stars

Bonavita, M; Fontanive, C; Gratton, R; Mužić, K; Desidera, S; Mesa, D; Biller, B; Scholz, A; Sozzetti, A; Squicciarini, V (2022). Results from The COPAINS Pilot Survey: Four new brown dwarfs and a high companion detection rate for accelerating stars. Monthly notices of the Royal Astronomical Society, 513(4), pp. 5588-5605. Oxford University Press 10.1093/mnras/stac1250

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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 (Δμ) between different astrometric catalogues. We observed 25 stars and detected ten companions, including four new BDs: HIP 21152 B, HIP 29724 B, HD 60584 B, and HIP 63734 B. Our results clearly demonstrate 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 (Finely 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 Δμ. 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 in the number of potential benchmarks for BD and planet formation and evolution theories.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Center for Space and Habitability (CSH)

UniBE Contributor:

Fontanive, Clémence

Subjects:

500 Science > 520 Astronomy

ISSN:

0035-8711

Publisher:

Oxford University Press

Language:

English

Submitter:

Andrea Stettler

Date Deposited:

09 Jun 2022 15:12

Last Modified:

05 Dec 2022 16:20

Publisher DOI:

10.1093/mnras/stac1250

BORIS DOI:

10.48350/170545

URI:

https://boris.unibe.ch/id/eprint/170545

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