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arXiv · 2109.14312

GTC/CanariCam deep mid-infrared imaging survey of northern stars within 5 pc

Bartosz Gauza·Víctor J. S. Béjar·Rafael Rebolo·Carlos Álvarez·María Rosa Zapatero Osorio·Gabriel Bihain·José A. Caballero·David J. Pinfield·Charles M. Telesco·Christopher Packham
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Abstract

In this work we present the results of a direct imaging survey for brown dwarf companions around the nearest stars at the mid-infrared 10 micron range ($\lambda_{c}$=8.7$\mu$m, $\Delta\lambda$=1.1$\mu$m) using the CanariCam instrument at the 10.4 m Gran Telescopio Canarias (GTC). We imaged the 25 nearest stellar systems within 5 pc of the Sun at declinations $\delta > -25^{\circ}$ (at least half have planets from radial velocity), reaching a mean detection limit of 11.3$\pm$0.2 mag (1.5 mJy) in the Si-2 8.7$\mu$m band over a range of angular separations from 1 to 10 arcsec. This would have allowed us to uncover substellar companions at projected orbital separations between $\sim$2 and 50 au, with effective temperatures down to 600 K and masses greater than 30 $M_{Jup}$ assuming an average age of 5 Gyr and down to the deuterium-burning mass limit for objects with ages $<$1 Gyr. From the non-detection of such companions, we determined upper limits on their occurrence rate at depths and orbital separations yet unexplored by deep imaging programs. For the M dwarfs, main components of our sample, we found with a 90% confidence level that less than 20% of these low-mass stars have L and T-type brown dwarf companions with $m \gtrsim 30 M_{Jup}$ and $T_{eff} \gtrsim$ 600 K at $\sim$3.5--35 au projected orbital separations.

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Bartosz Gauza, Víctor J. S. Béjar, Rafael Rebolo, Carlos Álvarez, María Rosa Zapatero Osorio, Gabriel Bihain, José A. Caballero, David J. Pinfield, Charles M. Telesco, Christopher Packham. 2021-09-29. GTC/CanariCam deep mid-infrared imaging survey of northern stars within 5 pc. https://doi.org/10.3847/1538-4357%2Fac2c0a

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