Published February 26, 2021 | Version v1
Poster Open

Large Adaptive optics Survey for Substellar Objects (LASSO) at wide separations around young, nearby, low-mass stars with Robo-AO

  • 1. Institute for Astronomy, University of Hawaii
  • 2. Department of Astronomy, The University of Texas at Austin
  • 3. Division of Physics, Mathematics, and Astronomy, California Institute of Technology
  • 4. Astronomy & Astrophysics Department, University of California, Santa Cruz
  • 5. Department of Physics and Astronomy, University of North Carolina at Chapel Hill




The purpose of the Large Adaptive optics Survey for Substellar Objects (LASSO) is to directly image new substellar companions (<70 MJup) at wide orbital separations (\(\gtrsim\)50 AU) around young (\(\lesssim\)300 Myrs), nearby (<100 pc), low-mass (0.1-0.8 MSun) stars. We report on 427 young stars imaged in the visible (i') and near-infrared (J or H) simultaneously with Robo-AO on the Kitt Peak 2.1-m telescope and later the Maunakea UH 2.2-m telescope. To undertake the observations, we commissioned a new infrared camera on Robo-AO that uses a low-noise high-speed SAPHIRA detector. We detected 122 companion candidates around 110 stars, of which 58 companions are physically associated based on Gaia DR2 parallaxes and proper motions, another 52 require follow-up observations to confirm physical association, and 12 are background objects. The majority of confirmed and pending candidates are stellar companions, with ~5 being potentially substellar and requiring follow-up observations for confirmation. We also detected a 43\(\pm\)9 MJup and an 81\(\pm\)5 MJup companion that were previously reported. The companion separations range from 2-1112 AU and reach contrast ratios of 7.7 magnitudes in the near infrared compared to the primary. We found 34 of our targets have acceleration measurements derived from Hipparcos-Gaia proper motions. Of those, 58% of the 12 stars with companion candidates have significant accelerations (\(\chi\)2 >11.8), while only 23% of the remaining 22 stars with no detected companion have significant accelerations. The significance of the acceleration decreases with increasing companion separation. These young accelerating low-mass stars with companions will eventually yield dynamical masses with future orbit monitoring.



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